PAX2-Related Disorder

Synonyms: Papillorenal Syndrome, Renal Coloboma Syndrome

Bower MA, Schimmenti LA, Eccles MR.

Publication Details

Estimated reading time: 25 minutes


Clinical characteristics.

PAX2-related disorder is an autosomal dominant disorder associated with renal and eye abnormalities. The disorder was originally referred to as renal coloboma syndrome and characterized by renal hypodysplasia and abnormalities of the optic nerve; with improved access to molecular testing, a wider range of phenotypes has been recognized in association with pathogenic variants in PAX2. Abnormal renal structure or function is noted in 92% of affected individuals and ophthalmologic abnormalities in 77% of affected individuals. Renal abnormalities can be clinically silent in rare individuals. In most individuals, clinically significant renal insufficiency / renal failure is reported. End-stage renal disease requiring renal transplant is not uncommon. Uric acid nephrolithiasis has been reported. Ophthalmologic abnormalities are typically described as optic nerve coloboma or dysplasia. Iris colobomas have not been reported in any individual with PAX2–related disorder. Ophthalmologic abnormalities may significantly impair vision in some individuals, while others have subtle changes only noted after detailed ophthalmologic examination. Additional clinical findings include high-frequency sensorineural hearing loss, soft skin, and ligamentous laxity. PAX2 pathogenic variants have been identified in multiple sporadic and familial cases of nonsyndromic renal disease including renal hypodysplasia and focal segmental glomerulosclerosis.


The diagnosis of PAX2-related disorder is established in a proband with the characteristic renal and/or eye findings by the identification of a heterozygous pathogenic variant in PAX2 by molecular genetic testing. Among individuals with apparently nonsyndromic renal hypodysplasia and in families with autosomal dominant isolated focal segmental glomerulosclerosis, pathogenic variants in PAX2 have been identified in approximately 8% and 4%, respectively.


Treatment of manifestations: Ongoing treatment of hypertension and/or vesicoureteral reflux; renal replacement therapy (dialysis and/or renal transplantation) for end-stage renal disease; low vision aids for significant visual impairment.

Prevention of secondary complications: Use of protective eyewear to prevent retinal detachment.

Surveillance: Follow up by a nephrologist to monitor renal function and blood pressure and an ophthalmologist to monitor vision, with periodic audiometric evaluations.

Evaluation of relatives at risk: Offer molecular genetic testing if a PAX2 pathogenic variant has been identified in an affected family member. If no PAX2 pathogenic variant has been found, perform dilated ophthalmologic examination, renal ultrasound examination, tests of renal function, uric acid levels, and urinalysis; measure blood pressure.

Genetic counseling.

PAX2-related disorder is inherited in an autosomal dominant manner. Approximately 65% of probands with a documented PAX2 pathogenic variant have a negative family history. In such cases, the negative family history may be explained by a de novo pathogenic variant, unrecognized symptoms in the parents, or parental germline mosaicism for a PAX2 pathogenic variant. Both maternal and paternal germline mosaicism, with unaffected parents having more than one affected child with a pathogenic variant, have been reported. Prenatal testing and preimplantation genetic testing are possible if the pathogenic PAX2 pathogenic variant has been identified in the family.


Renal coloboma syndrome (or papillorenal syndrome) was the name given to an autosomal dominant condition associated with renal hypodysplasia and abnormalities of the optic nerve and a heterozygous pathogenic variant in PAX2. With improved access to molecular genetic testing, more individuals have been identified and it has become clear that multiple phenotypes beyond that of classic renal coloboma syndrome may be associated with pathogenic variants in PAX2. The authors feel that the term "PAX2-related disorder" best reflects this wide phenotypic variability.

There are no formal diagnostic criteria for PAX2-related disorder.

Suggestive Findings

PAX2-related disorder should be suspected in individuals with the following clinical findings in the kidneys and/or eyes.

Note: PAX2 pathogenic variants are more likely to be identified in individuals with both ophthalmologic and renal involvement, but are increasingly recognized in cases with isolated renal findings such as renal hypodysplasia or focal segmental glomerulosclerosis [Barua et al 2014].


Abnormalities of kidney structure and/or function are the most frequent finding in individuals with PAX2-related disorder, noted in 159 (92%) of 173 cases [Bower et al 2012].

  • Hypoplastic kidneys characterized on ultrasound examination by hypoplasia (small size for age) and hyperechogenicity [Schimmenti et al 1995]. Renal hypoplasia is usually bilateral, although marked variability between kidneys can be observed (e.g., 1 kidney small or absent, 1 of normal size).
  • Renal hypodysplasia, characterized histologically by reduced number of nephrons, small kidney size, and disorganized renal tissue [Weber et al 2006]. Renal hypodysplasia was the most common renal finding in 114 (65%) of 173 affected individuals [Bower et al 2012].
  • Multicystic dysplastic kidney, characterized histologically by cystic or dysplastic kidneys exhibiting some degree of disorganization of the kidney architecture. Multicystic dysplastic kidneys are observed in about 6%-10% of affected individuals [Fletcher et al 2005, Bower et al 2012].
  • Oligomeganephronia, a pathologic finding characterized by fewer-than-normal glomeruli that are enlarged in size [Salomon et al 2001]. Note: Oligomeganephronia is not pathognomonic for PAX2-related disorder.
  • Renal insufficiency and end-stage renal disease (ESRD). Because most data are aggregated from individual case reports and small case series, the exact incidence of Stage 5 chronic kidney disease requiring kidney transplantation is not precisely known. One study reported the mean age at diagnosis of ESRD in PAX2-related disorder was 19.5 years (range: birth to 79 years) [Bower et al 2012].
  • Vesicoureteral reflux was reported in 25 (14%) of 173 affected individuals in a large literature review and case series [Bower et al 2012].
  • Other renal anomalies in the congenital anomalies of the kidney and urinary tract (CAKUT). Each of the following findings in the CAKUT spectrum has been reported in fewer than five individuals with PAX2-related disorder: ureteropelvic junction obstruction; medullary sponge kidney; horseshoe kidney; pyeloureteral duplication; and renal malrotation.
  • Focal segmental glomerulosclerosis (FSGS). PAX2 pathogenic variants have been documented in pedigrees with isolated autosomal dominant FSGS [Barua et al 2014, Okumura et al 2014].
  • Uncommon non-CAKUT renal findings. Uric acid nephrolithiasis (kidney stones) has been reported in several individuals; an intrarenal teratoma was reported in a single individual [Choi et al 2005, Bower et al 2012].


The primary eye finding is dysplasia of the optic nerve that ranges from severe to mild. Abnormalities of the optic nerve have been identified in 125 (72%) of 173 affected individuals [Bower et al 2012].

  • The most severe form is characterized by an apparently enlarged disc in which the vessels that normally exit from the center of the disc exit instead from the periphery [Schimmenti et al 2003]. Associated abnormalities may include deep excavation of the optic nerve head with redundant fibroglial tissue.
  • A milder form is an optic nerve pit characterized by a relatively localized (or sub-total) excavation of the optic disc.
  • The mildest form is the exiting of the retinal vessels from the periphery of the disc without malformation of the disc itself.

Note: (1) Differences exist in the terminology used to designate dysplasia of the optic nerve with abnormal passage of retinal vessels from the periphery of the optic nerve head. Some ophthalmologists refer to this finding as congenital excavation of the optic nerve and others as "optic nerve coloboma." However, the use of the term coloboma can be confusing in this setting because coloboma usually refers to non-closure of the optic fissure during the seventh week of gestation, resulting in typical uveal colobomas (iris and retinal colobomas). The developmental mechanism underlying the optic nerve abnormalities observed in PAX2-related disorder is under investigation in animal models: in both mouse and zebrafish, homozygous loss-of-function alleles of Pax2/pax2a result in failed optic fissure closure [Schimmenti 2009]. (2) Some have described one of the optic nerve findings in this syndrome as "morning glory anomaly," defined as a wide and deeply excavated optic nerve with a central glial tuft and all vessels exiting abnormally at the periphery of the nerve, giving the appearance of a morning glory flower. However, it is debated whether use of the term morning glory anomaly is appropriate to describe the optic nerve malformation in PAX2 -related disorder because it may be a misnomer for the dysplasia of the optic nerve typically seen in this syndrome.

Retinal findings in addition to optic nerve findings have been described in 23 (13%) of 173 affected individuals. Retinal coloboma (defined as absence of retinal tissue in the nasal ventral portion of the retina resulting from failure of closure of the uveal tract) has been reported in six individuals. Other retinal findings reported include: abnormal retinal pigment epithelium, abnormal retinal vessels, macular anomalies, and chorioretinal degeneration.

Less common associated eye malformations include the following [Sanyanusin et al 1995a, Sanyanusin et al 1995b, Schimmenti et al 1995, Schimmenti et al 1999, Amiel et al 2000, Dureau et al 2001, Schimmenti et al 2003, Bower et al 2012]:

  • Scleral staphyloma, defined as posterior bulging of the eye wall (sclera), is likely a secondary thinning of neural-crest-derived tissue in the area of the anatomically abnormal optic nerve head. Retinal thinning and myopia may be secondary to enlargement of the globe.
  • Optic nerve cyst, a cystic dilatation of the optic nerve posterior to the globe, is observed by cranial imaging (e.g., MRI). The cyst likely results from incomplete regression of the primordial optic stalk, followed by accumulation of fluid in its potential space.
  • Macular abnormalities including macular degeneration, hyperpigmentation of the macula, cystic degeneration of the macula, and papillomacular detachment have been reported in a limited number of affected individuals.
  • Lens abnormalities. Lens opacity and posterior lens luxation have been reported in one affected individual each. It is not clear whether these findings are coincidental or part of this disorder.

Note: (1) Some individuals with PAX2-related disorder may not have vision loss and hence, examination of the fundus through a dilated pupil may be necessary to observe optic nerve abnormalities [Chung et al 2001]. (2) Iris coloboma has not been observed in persons with PAX2-related disorder.


A wide range of non-renal and non-ophthalmologic findings including high-frequency sensorineural hearing loss – or more rarely, CNS malformations, developmental delay, hyperuricemia (gout), soft skin, joint laxity, and elevated pancreatic amylase – have been reported in individuals with PAX2-related disorder. Each of these findings is reported in a limited number of individuals and a definitive causal connection with PAX2 variants has not been established.

Establishing the Diagnosis

The diagnosis of PAX2-related disorder is established in a proband with the characteristic renal and/or eye findings by the identification of a heterozygous pathogenic (or likely pathogenic) variant in PAX2 on molecular genetic testing (see Table 1).

Note: Per ACMG variant interpretation guidelines, the terms "pathogenic variants" and "likely pathogenic variants" are synonymous in a clinical setting, meaning that both are considered diagnostic and both can be used for clinical decision making. Reference to "pathogenic variants" in this section is understood to include any likely pathogenic variants.

Molecular genetic testing approaches can include single-gene testing, chromosomal microarray analysis (CMA), use of a multigene panel, and more comprehensive genomic testing:

  • Single-gene testing. Sequence analysis of PAX2 is performed first and followed by gene-targeted deletion/duplication analysis if no pathogenic variant is found.
  • Chromosomal microarray analysis (CMA) – if not already performed – may be obtained to detect genome-wide deletions/duplications (including PAX2).
    Note: A single case of PAX2-related disorder with an apparently balanced de novo t(10;13) translocation with a breakpoint at the PAX2 locus has been reported [Narahara et al 1997]. Because balanced rearrangements may not be detected by CMA, karyotype analysis could be considered in cases with a compelling clinical phenotype and normal PAX2 sequencing and gene-targeted deletion/duplication analysis.
  • A multigene panel that includes PAX2 and other genes of interest (see Differential Diagnosis) may be considered. Note: (1) The genes included in the panel and the diagnostic sensitivity of the testing used for each gene vary by laboratory and are likely to change over time. (2) Some multigene panels may include genes not associated with the condition discussed in this GeneReview; thus, clinicians need to determine which multigene panel is most likely to identify the genetic cause of the condition while limiting identification of variants of uncertain significance and pathogenic variants in genes that do not explain the underlying phenotype. (3) In some laboratories, panel options may include a custom laboratory-designed panel and/or custom phenotype-focused exome analysis that includes genes specified by the clinician. (4) Methods used in a panel may include sequence analysis, deletion/duplication analysis, and/or other non-sequencing-based tests.
    For an introduction to multigene panels click here. More detailed information for clinicians ordering genetic tests can be found here.
  • More comprehensive genomic testing (when available) including exome sequencing and genome sequencing may be considered. Such testing may provide or suggest a diagnosis not previously considered (e.g., mutation of a different gene or genes that results in a similar clinical presentation).
    For an introduction to comprehensive genomic testing click here. More detailed information for clinicians ordering genomic testing can be found here.
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Table 1.

Molecular Genetic Testing Used in PAX2-Related Disorder

Clinical Characteristics

Clinical Description

PAX2-related disorder is associated with abnormalities involving the kidneys and/or the eyes. The original PAX2-related disorder known as renal coloboma syndrome is characterized by hypodysplastic kidneys and optic nerve abnormalities (most commonly optic nerve dysplasia) with or without optic nerve or retinal coloboma [Sanyanusin et al 1995a, Schimmenti et al 1995, Schimmenti et al 2003].

Variability. The clinical findings vary even within families, with some family members having either renal manifestations or optic nerve abnormalities and others having both. The severity of renal malformations can range within a family from absence of clinical symptoms to severe fetal renal failure.

In some instances a detailed eye examination is necessary to reveal the ocular findings of PAX2-related disorder in individuals presenting with characteristic renal findings [Chung et al 2001, Nishimoto et al 2001, Salomon et al 2001] or renal evaluation is needed in individuals with characteristic eye findings [Parsa et al 2001].

A wide range of kidney and eye findings can be found in individuals with PAX2-related disorder (see Suggestive Findings).

Renal disease. Renal insufficiency/failure can occur at any age. The age at diagnosis of Stage 5 chronic kidney disease ranges from birth to 79 years.

The natural history of vesicoureteral reflux varies: in some individuals ureteral reimplantation has been required [Schimmenti et al 1995]; in others the reflux has spontaneously resolved [Ford et al 2001].

Eye abnormalities. Impaired visual acuity of one or both eyes is present in 75% of affected individuals; acuity ranges from light perception only to normal. Other findings can include nystagmus, myopia, and strabismus.

The natural history of visual acuity in individuals with PAX2-related disorder has not been prospectively studied. In some instances, significant changes in visual acuity have been reported. Visual acuity deteriorated in one person as a result of retinal detachment [Ford et al 2001]. One person reported acute vision loss resulting in a change of visual acuity from 20/80 to light perception only [Schimmenti et al 1995]; however, the cause of vision loss was unexplained as there was no evidence of detachment or macular changes [Schimmenti, unpublished observation].

Other. Less commonly reported findings in affected individuals include high-frequency hearing loss, soft skin, and ligamentous laxity. The age of onset and progression of hearing loss remain unknown and have not been evaluated prospectively. The hearing loss, when present, has been discovered in childhood and is bilateral high-frequency sensorineural hearing loss [Schimmenti et al 1995, Bower et al 2012].

Prenatal phenotype. Abnormalities including oligohydramnios/anhydramnios, cystic renal dysplasia, multicystic dysplastic kidneys, and renal hypoplasia were reported on prenatal ultrasound in 18 individuals with PAX2 pathogenic variants [Bower et al 2012]. Seven fetuses with a confirmed PAX2 pathogenic variant and severe prenatal renal failure (Potter sequence) have been reported [Martinovic-Bouriel et al 2010, Bower et al 2012]. In several instances, parents with mild renal disease had pregnancies where the fetus presented with severe renal disease in utero.

Genotype-Phenotype Correlations

Review of all reported cases to date does not reveal a consistent genotype/phenotype correlation. This is most dramatically illustrated by the tremendous intrafamilial variability in the severity of ocular and renal findings. To date, no clear evidence suggests that the location of a pathogenic variant (paired domain, octapeptide domain, partial homeodomain, or transactivation domain) or the type of pathogenic variant (missense variant, nonsense variant, or gene deletion) consistently predicts the clinical phenotype.


Only one individual with a pathogenic variant in PAX2 in whom renal and ophthalmologic examinations were performed and documented as normal has been reported [Bower et al 2012]. Thus, penetrance appears to be greater than 99%. In individuals with pathogenic variants in PAX2, the penetrance of eye malformations is at least 77% [Bower et al 2012]. This should be viewed as a minimum figure, as fully 21% of individuals with PAX2 pathogenic variants have not had a dilated eye examination to evaluate for subclinical abnormalities of the optic nerve. The penetrance for renal malformations or renal disease is at least 92%. Again, this figure should be viewed as a minimum, as some individuals with pathogenic variants have not had full renal evaluations.


Terms previously used for renal coloboma (papillorenal syndrome) syndrome:

  • Coloboma-ureteral-renal syndrome
  • Optic nerve coloboma with renal disease
  • Coloboma of the optic nerve with renal disease
  • Optic coloboma-vesicoureteral reflux-renal anomalies

Controversy regarding the naming of this syndrome has caused confusion in the field. The condition was named renal coloboma syndrome based on the presence of kidney abnormalities and the optic nerve abnormalities described by the ophthalmologists who identified the original families found to have PAX2 pathogenic variants [Sanyanusin et al 1995a, Sanyanusin et al 1995b]. In 2001, Parsa et al identified a family with similar optic nerve and renal abnormalities where no variants in PAX2 were identified and suggested that the name of the condition be changed to papillorenal syndrome; it is unclear if the two entities are related.


The prevalence of PAX2-related disorder is unknown. At the time of the most recent update, 243 affected individuals from 124 different families are recorded in the PAX2 locus-specific database ( There is no evidence for a significant founder effect in any population.

Differential Diagnosis

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Table 2.

Disorders to Consider in the Differential Diagnosis of PAX2-Related Disorder


Evaluations Following Initial Diagnosis

To establish the extent of disease and needs in an individual diagnosed with PAX2-related disorder, the following are recommended if they have not already been completed:

  • Evaluation of renal structure by renal ultrasound examination
  • Measurement of renal function by serum electrolyte concentrations, BUN, and creatinine
  • Urinalysis to evaluate for the presence of blood and protein
  • Evaluation for vesicoureteral reflux, by voiding cytourethrogram (VCUG)
  • Dilated eye examination
  • Audiologic assessment (See Deafness and Hereditary Hearing Loss Overview for details of audiologic assessment.)
  • Consultation with a clinical geneticist and/or genetic counselor

Treatment of Manifestations

A team approach that includes specialists in ophthalmology, nephrology, audiology, and clinical genetics is recommended.

Management is focused on preventing complications of end-stage renal disease (ESRD) and/or vision loss resulting from retinal detachment.

  • Ongoing treatment of hypertension and/or vesicoureteral reflux (if present) may preserve renal function.
  • ESRD is treated with renal replacement therapy (i.e., dialysis and/or renal transplantation).
  • Low vision experts can assist with adaptive functioning of those with significant vision loss.

Prevention of Secondary Complications

Prevention of retinal detachment in those with congenital optic nerve abnormalities includes close follow up with an ophthalmologist and use of protective eyewear.


No disease-specific guidelines have been developed. The following ongoing evaluations are recommended in all individuals with PAX2-related disorder.

  • Follow up by a nephrologist to monitor renal function and blood pressure
  • Follow up by an ophthalmologist to monitor vision. Any change in vision could indicate a retinal detachment and should be treated as a medical emergency.
  • Audiometric evaluation with periodic follow up

Agents/Circumstances to Avoid

Avoid the following:

  • Use of medications known to affect renal function (requires consultation with a specialist in nephrology)
  • Contact sports

Evaluation of Relatives at Risk

It is appropriate to clarify the genetic status of apparently asymptomatic at-risk relatives of an affected individual by molecular genetic testing of the PAX2 pathogenic variant in the family in order to identify as early as possible those who would benefit from prompt initiation of treatment and preventive measures.

See Genetic Counseling for issues related to testing of at-risk relatives for genetic counseling purposes.

Pregnancy Management

It is important that a female with PAX2-related disorder have a thorough renal evaluation prior to becoming pregnant. Individuals with clinical renal disease should consult with appropriate professionals including nephrologists and maternal-fetal medicine specialists to establish a plan for medical management during pregnancy.

Therapies Under Investigation

Search in the US and EU Clinical Trials Register in Europe for information on clinical studies for a wide range of diseases and conditions. Note: There may not be clinical trials for this disorder.

Genetic Counseling

Genetic counseling is the process of providing individuals and families with information on the nature, mode(s) of inheritance, and implications of genetic disorders to help them make informed medical and personal decisions. The following section deals with genetic risk assessment and the use of family history and genetic testing to clarify genetic status for family members; it is not meant to address all personal, cultural, or ethical issues that may arise or to substitute for consultation with a genetics professional. —ED.

Mode of Inheritance

PAX2-related disorder is inherited in an autosomal dominant manner.

Risk to Family Members

Parents of a proband

  • Approximately 35% of individuals with PAX2-related disorder have a recognized clinically affected parent [Bower et al 2012]. Because tremendous variability in the severity of ocular and renal findings is observed within families, parents may be more or less severely affected than their offspring.
  • Approximately 65% of probands with PAX2-related disorder represent simplex cases (i.e., a single occurrence in a family). Molecular testing in 23 (41%) of 56 simplex cases confirmed the de novo origin for the pathogenic variant, while parental testing was not performed in the remaining 33 cases [Bower et al 2012].
  • Recommendations for the evaluation of parents of a proband with an apparent de novo pathogenic variant include molecular genetic testing for the PAX2 pathogenic variant identified in the proband.
  • If the pathogenic variant found in the proband cannot be detected in the leukocyte DNA of either parent and/or neither parent has clinical findings consistent with a diagnosis of PAX2-related disorder, possible explanations include a de novo pathogenic variant in the proband or germline mosaicism in a parent. Both maternal and paternal germline mosaicism have been reported in PAX2-related disorder [Amiel et al 2000, Cheong et al 2007].
  • Note: If the parent is the individual in whom the pathogenic variant first occurred, the parent may have somatic mosaicism for the variant and may be mildly/minimally affected.
    Ophthalmologic abnormalities consistent with PAX2-related disorder have been reported in a parent without a PAX2 pathogenic variant who had two children with a PAX2 pathogenic variant. It was hypothesized that this parent had somatic (and germline) mosaicism, but the pathogenic variant was absent in the tissues analyzed (leukocytes, fibroblasts, oral mucosa) [Bower et al 2012].

Sibs of a proband. The risk to the sibs of the proband depends on the status of the proband's parents:

  • If a parent of the proband is affected, the risk to the sibs is 50%.
  • If the parents of a proband with PAX2-related disorder have been tested for the pathogenic variant identified in the proband and:
    • A parent of the proband has the PAX2 pathogenic variant, the risk to the sibs of inheriting the variant is 50%. Because of intrafamilial clinical variability, it is not possible to predict the phenotype in sibs who have inherited a pathogenic variant.
    • If the PAX2 pathogenic variant found in the proband cannot be detected in the leukocyte DNA of either parent, the risk to sibs is slightly greater than that of the general population because of the possibility of parental germline mosaicism. Germline mosaicism, in which parents who test negative for the familial PAX2 pathogenic variant have more than one affected child, has been documented in two families [Bower et al 2012].

Offspring of a proband. Each child of an individual with PAX2-related disorder has a 50% chance of inheriting the PAX2 pathogenic variant.

Other family members. The risk to other family members depends on the status of the proband's parents: if a parent is affected and/or has a PAX2 pathogenic variant, the parent's family members are at risk.

Related Genetic Counseling Issues

See Evaluation of Relatives at Risk for information on evaluating at-risk relatives for the purpose of early diagnosis and treatment.

Testing of at-risk asymptomatic individuals. It is appropriate to consider molecular genetic testing of at-risk asymptomatic family members in order to guide vision and renal management (see Management, Surveillance). Molecular genetic testing can only be used for testing at-risk relatives if a PAX2 pathogenic variant has been identified in an affected family member. Because early detection of at-risk individuals affects medical management, testing of individuals during childhood who have no symptoms is beneficial. It is appropriate to provide education and genetic counseling for at-risk individuals younger than age 18 years and their parents prior to genetic testing.

Considerations in families with an apparent de novo pathogenic variant. When neither parent of a proband with an autosomal dominant condition has the pathogenic variant identified in the proband or clinical evidence of the disorder, the pathogenic variant is likely de novo. However, non-medical explanations including alternate paternity or maternity (e.g., with assisted reproduction) and undisclosed adoption could also be explored.

Family planning

  • The optimal time for determination of genetic risk and discussion of the availability of prenatal/preimplantation genetic testing is before pregnancy.
  • It is appropriate to offer genetic counseling (including discussion of potential risks to offspring and reproductive options) to young adults who are affected or at risk.

Prenatal Testing and Preimplantation Genetic Testing

Molecular genetic testing. Once the PAX2 pathogenic variant has been identified in an affected family member, prenatal testing for a pregnancy at increased risk and preimplantation genetic testing are possible.

Differences in perspective may exist among medical professionals and within families regarding the use of prenatal testing. While most centers would consider use of prenatal testing to be a personal decision, discussion of these issues may be helpful.

Prenatal fetal ultrasound examination of an at-risk pregnancy or known affected pregnancy may be used during the later stages of pregnancy to detect renal malformations and assess amniotic fluid volume, as findings could affect the well-being of the newborn or warrant further evaluation after birth.


GeneReviews staff has selected the following disease-specific and/or umbrella support organizations and/or registries for the benefit of individuals with this disorder and their families. GeneReviews is not responsible for the information provided by other organizations. For information on selection criteria, click here.

  • International Children's Anophthalmia Network (ICAN)
    Phone: 800-580-ican
  • Kidney Foundation of Canada
    Phone: 514-369-4806; 800-361-7494
  • National Eye Institute
    Phone: 301-496-5248
  • National Kidney Foundation
    Phone: 855-NKF-CARES; 855-653-2273

Molecular Genetics

Information in the Molecular Genetics and OMIM tables may differ from that elsewhere in the GeneReview: tables may contain more recent information. —ED.

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Table A.

PAX2-Related Disorder: Genes and Databases

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Table B.

OMIM Entries for PAX2-Related Disorder (View All in OMIM)

Molecular Pathogenesis

The pattern of abnormalities in PAX2-related disorder is consistent with the known expression pattern of PAX2 during embryonic development. Porteous et al [2000] and Torban et al [2000] have demonstrated in mouse models and tissue culture that normal biallelic PAX2 expression is needed to prevent programmed cell death.

Gene structure. PAX2 contains 12 coding exons. Alternative splicing of this gene results in multiple transcript variants. The longest transcript variant, NM_003990.3, has 11 exons. None of the known transcripts contains all 12 coding exons. See Table A, Gene for a detailed summary of gene and protein information.

Pathogenic variants. See Table A, Locus Specific. To date, nearly 90 different pathogenic variants have been reported in the PAX2 coding exons and adjoining intronic sequences [Bower et al 2012].

Frameshift variants are the most common type; nonsense and missense variants, splice site changes, and in-frame duplications have also been reported. Pathogenic variants tend to cluster in the paired domain (exons 2-4), the homeodomain (exon 7), and the 5' portion of the transactivation domain (exon 8). A limited number of missense variants have been reported in exons 9-12, but the pathogenicity of these variants is not clearly established. A small number of genomic deletions and rearrangements have been reported. Partial-gene deletions are not a common pathogenic mechanism [Karger et al 2013].

The most common recurring pathogenic variant, c.76dupG (previously called c.619insG), is a duplication of a G residue in a stretch of seven Gs and has been reported in more than 25 independent families.

Table Icon

Table 3.

PAX2 Pathogenic Variants Discussed in This GeneReview

Normal gene product. NM_003990.3 encodes a PAX-2 isoform of 431 amino acids (NP_003981.2). Paired box protein PAX-2 is a DNA-binding protein characterized by an N-terminal paired domain, a bipartite helix-loop-helix domain, a small octapeptide domain, a truncated homeodomain, and a proline/serine/threonine-rich C-terminal domain. Multiple isoforms, by alternative splicing of exons 6, 10, and 12, are known to exist.

Abnormal gene product. Review of ExAC ( indicates that PAX2 is relatively intolerant of loss of function or missense alleles. The majority of PAX2 pathogenic variants are expected to result either in the loss of expression from one allele or in expression of a significantly truncated protein.

To date, all clearly pathogenic in-frame variants (missense, in-frame deletions, and in-frame duplications) are located in the paired domain (exons 2-4). It is not known if these pathogenic variants exert their effect by reducing the binding to normal DNA targets or by allowing binding to abnormal DNA targets. Six missense variants have been reported outside of the paired domain. Each of these variants has been reported in a single individual and the evidence for pathogenicity is not as strong as with other PAX2 variants.

Chapter Notes

Revision History

  • 8 February 2018 (ha) Comprehensive update posted live
  • 20 November 2014 (me) Comprehensive update posted live
  • 12 July 2012 (me) Comprehensive update posted live
  • 8 June 2007 (me) Review posted live
  • 8 December 2006 (las) Original submission


Published Guidelines / Consensus Statements

  • Committee on Bioethics, Committee on Genetics, and American College of Medical Genetics and Genomics Social, Ethical, Legal Issues Committee. Ethical and policy issues in genetic testing and screening of children. Available online. 2013. Accessed 6-21-22.

  • National Society of Genetic Counselors. Position statement on genetic testing of minors for adult-onset conditions. Available online. 2018. Accessed 6-21-22.

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