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Fanconi anemia complementation group B(FANCB)

MedGen UID:
336901
Concept ID:
C1845292
Disease or Syndrome
Synonyms: FANCB; FANCONI PANCYTOPENIA, TYPE 2
 
Gene (location): FANCB (Xp22.2)
 
Monarch Initiative: MONDO:0010351
OMIM®: 300514

Disease characteristics

Excerpted from the GeneReview: Fanconi Anemia
Fanconi anemia (FA) is characterized by physical abnormalities, bone marrow failure, and increased risk for malignancy. Physical abnormalities, present in approximately 75% of affected individuals, include one or more of the following: short stature, abnormal skin pigmentation, skeletal malformations of the upper and/or lower limbs, microcephaly, and ophthalmic and genitourinary tract anomalies. Progressive bone marrow failure with pancytopenia typically presents in the first decade, often initially with thrombocytopenia or leukopenia. The incidence of acute myeloid leukemia is 13% by age 50 years. Solid tumors – particularly of the head and neck, skin, and genitourinary tract – are more common in individuals with FA. [from GeneReviews]
Authors:
Parinda A Mehta  |  Christen Ebens   view full author information

Additional descriptions

From OMIM
Fanconi anemia (FA) is a clinically and genetically heterogeneous disorder that causes genomic instability. Characteristic clinical features include developmental abnormalities in major organ systems, early-onset bone marrow failure, and a high predisposition to cancer. The cellular hallmark of FA is hypersensitivity to DNA crosslinking agents and high frequency of chromosomal aberrations pointing to a defect in DNA repair (summary by Deakyne and Mazin, 2011). Patients with FANCB mutations often present with multiple additional congenital anomalies, including the constellation of features designated VACTERL-H (see 314390), for vertebral defects, anal atresia, tracheoesophageal fistula, esophageal atresia, radial or renal dysplasia, and hydrocephalus. Many patients with these features die in early infancy before developing anemia (McCauley et al., 2011). For additional general information and a discussion of genetic heterogeneity of Fanconi anemia, see 227650.  http://www.omim.org/entry/300514
From MedlinePlus Genetics
Individuals with Fanconi anemia have an increased risk of developing a cancer of blood-forming cells in the bone marrow called acute myeloid leukemia (AML) or tumors of the head, neck, skin, gastrointestinal system, or genital tract. The likelihood of developing one of these cancers in people with Fanconi anemia is between 10 and 30 percent.

More than half of people with Fanconi anemia have physical abnormalities. These abnormalities can involve irregular skin coloring such as unusually light-colored skin (hypopigmentation) or café-au-lait spots, which are flat patches on the skin that are darker than the surrounding area. Other possible symptoms of Fanconi anemia include malformed thumbs or forearms and other skeletal problems including short stature; malformed or absent kidneys and other defects of the urinary tract; gastrointestinal abnormalities; heart defects; eye abnormalities such as small or abnormally shaped eyes; and malformed ears and hearing loss. People with this condition may have abnormal genitalia or malformations of the reproductive system. As a result, most affected males and about half of affected females cannot have biological children (are infertile). Additional signs and symptoms can include abnormalities of the brain and spinal cord (central nervous system), including increased fluid in the center of the brain (hydrocephalus) or an unusually small head size (microcephaly).

The major function of bone marrow is to produce new blood cells. These include red blood cells, which carry oxygen to the body's tissues; white blood cells, which fight infections; and platelets, which are necessary for normal blood clotting. Approximately 90 percent of people with Fanconi anemia have impaired bone marrow function that leads to a decrease in the production of all blood cells (aplastic anemia). Affected individuals experience extreme tiredness (fatigue) due to low numbers of red blood cells (anemia), frequent infections due to low numbers of white blood cells (neutropenia), and clotting problems due to low numbers of platelets (thrombocytopenia). People with Fanconi anemia may also develop myelodysplastic syndrome, a condition in which immature blood cells fail to develop normally.

Fanconi anemia is a condition that affects many parts of the body. People with this condition may have bone marrow failure, physical abnormalities, organ defects, and an increased risk of certain cancers.  https://medlineplus.gov/genetics/condition/fanconi-anemia

Clinical features

From HPO
Renal agenesis
MedGen UID:
154237
Concept ID:
C0542519
Congenital Abnormality
Agenesis, that is, failure of the kidney to develop during embryogenesis and development.
Micropenis
MedGen UID:
1633603
Concept ID:
C4551492
Congenital Abnormality
Abnormally small penis. At birth, the normal penis is about 3 cm (stretched length from pubic tubercle to tip of penis) with micropenis less than 2.0-2.5 cm.
Bilateral radial aplasia
MedGen UID:
336433
Concept ID:
C1848840
Finding
Missing radius bone on both sides associated with congenital failure of development.
Absent thumb
MedGen UID:
480441
Concept ID:
C3278811
Finding
Absent thumb, i.e., the absence of both phalanges of a thumb and the associated soft tissues.
Coarctation of aorta
MedGen UID:
1617
Concept ID:
C0003492
Congenital Abnormality
Coarctation of the aorta is a narrowing or constriction of a segment of the aorta.
Patent ductus arteriosus
MedGen UID:
4415
Concept ID:
C0013274
Congenital Abnormality
In utero, the ductus arteriosus (DA) serves to divert ventricular output away from the lungs and toward the placenta by connecting the main pulmonary artery to the descending aorta. A patent ductus arteriosus (PDA) in the first 3 days of life is a physiologic shunt in healthy term and preterm newborn infants, and normally is substantially closed within about 24 hours after bith and completely closed after about three weeks. Failure of physiologcal closure is referred to a persistent or patent ductus arteriosus (PDA). Depending on the degree of left-to-right shunting, PDA can have clinical consequences.
Ventricular septal defect
MedGen UID:
42366
Concept ID:
C0018818
Congenital Abnormality
A hole between the two bottom chambers (ventricles) of the heart. The defect is centered around the most superior aspect of the ventricular septum.
Fetal growth restriction
MedGen UID:
4693
Concept ID:
C0015934
Pathologic Function
An abnormal restriction of fetal growth with fetal weight below the tenth percentile for gestational age.
Growth delay
MedGen UID:
99124
Concept ID:
C0456070
Pathologic Function
A deficiency or slowing down of growth pre- and postnatally.
Esophageal atresia
MedGen UID:
4545
Concept ID:
C0014850
Congenital Abnormality
A developmental defect resulting in complete obliteration of the lumen of the esophagus such that the esophagus ends in a blind pouch rather than connecting to the stomach.
Duodenal atresia
MedGen UID:
75602
Concept ID:
C0266174
Congenital Abnormality
A developmental defect resulting in complete obliteration of the duodenal lumen, that is, an abnormal closure of the duodenum.
Low-set ears
MedGen UID:
65980
Concept ID:
C0239234
Congenital Abnormality
Upper insertion of the ear to the scalp below an imaginary horizontal line drawn between the inner canthi of the eye and extending posteriorly to the ear.
Overfolded helix
MedGen UID:
325239
Concept ID:
C1837731
Finding
A condition in which the helix is folded over to a greater degree than normal. That is, excessive curling of the helix edge, whereby the free edge is parallel to the plane of the ear.
Hydrocephalus
MedGen UID:
9335
Concept ID:
C0020255
Disease or Syndrome
Hydrocephalus is an active distension of the ventricular system of the brain resulting from inadequate passage of CSF from its point of production within the cerebral ventricles to its point of absorption into the systemic circulation.
Cerebellar hypoplasia
MedGen UID:
120578
Concept ID:
C0266470
Congenital Abnormality
Cerebellar hypoplasia is a descriptive term implying a cerebellum with a reduced volume, but a normal shape and is stable over time.
Hypoplasia of the corpus callosum
MedGen UID:
138005
Concept ID:
C0344482
Congenital Abnormality
Underdevelopment of the corpus callosum.
Ventriculomegaly
MedGen UID:
480553
Concept ID:
C3278923
Finding
An increase in size of the ventricular system of the brain.
Intellectual disability
MedGen UID:
811461
Concept ID:
C3714756
Mental or Behavioral Dysfunction
Intellectual disability, previously referred to as mental retardation, is characterized by subnormal intellectual functioning that occurs during the developmental period. It is defined by an IQ score below 70.
Delayed CNS myelination
MedGen UID:
867393
Concept ID:
C4021758
Anatomical Abnormality
Delayed myelination in the central nervous system.
Aplastic anemia
MedGen UID:
8063
Concept ID:
C0002874
Disease or Syndrome
Aplastic anemia is a serious disorder of the bone marrow that affects between 2 and 5 persons per million per year. About 75% of these cases are classified as idiopathic (Young, 2000). In about 15% of cases a drug or infection can be identified that precipitates the aplasia, although why only some individuals are susceptible is unclear. In about 5 to 10% of patients, the aplastic anemia is constitutional--i.e., is familial or presents with one or more associated somatic abnormalities (summary by Vulliamy et al., 2002).
Thrombocytopenia
MedGen UID:
52737
Concept ID:
C0040034
Disease or Syndrome
A reduction in the number of circulating thrombocytes.
Abnormal vertebral morphology
MedGen UID:
371742
Concept ID:
C1834129
Anatomical Abnormality
An abnormality of one or more of the vertebrae.
Tracheoesophageal fistula
MedGen UID:
21228
Concept ID:
C0040588
Anatomical Abnormality
An abnormal connection (fistula) between the esophagus and the trachea.
Abnormal lung lobation
MedGen UID:
195782
Concept ID:
C0685695
Congenital Abnormality
A developmental defect in the formation of pulmonary lobes.
Short neck
MedGen UID:
99267
Concept ID:
C0521525
Finding
Diminished length of the neck.
Single umbilical artery
MedGen UID:
278026
Concept ID:
C1384670
Congenital Abnormality
Single umbilical artery (SUA) is the absence of one of the two umbilical arteries surrounding the fetal bladder and in the fetal umbilical cord.
Hypogonadism
MedGen UID:
5711
Concept ID:
C0020619
Disease or Syndrome
A decreased functionality of the gonad.
Hypergonadotropic hypogonadism
MedGen UID:
184926
Concept ID:
C0948896
Disease or Syndrome
Reduced function of the gonads (testes in males or ovaries in females) associated with excess pituitary gonadotropin secretion and resulting in delayed sexual development and growth delay.
Optic disc hypoplasia
MedGen UID:
224879
Concept ID:
C1298695
Finding
Underdevelopment of the optic disc, that is of the optic nerve head, where ganglion cell axons exit the eye to form the optic nerve.
Abnormality of chromosome stability
MedGen UID:
1631925
Concept ID:
C4551705
Cell or Molecular Dysfunction
A type of chromosomal aberration characterised by reduced resistance of chromosomes to change or deterioration.

Recent clinical studies

Etiology

Alix-Panabières C, Cayrefourcq L, Mazard T, Maudelonde T, Assenat E, Assou S
Clin Chem 2017 Mar;63(3):700-713. Epub 2016 Dec 22 doi: 10.1373/clinchem.2016.263582. PMID: 28007957
Umaña LA, Magoulas P, Bi W, Bacino CA
Am J Med Genet A 2011 Dec;155A(12):3071-4. Epub 2011 Nov 3 doi: 10.1002/ajmg.a.34296. PMID: 22052692
Meetei AR, Levitus M, Xue Y, Medhurst AL, Zwaan M, Ling C, Rooimans MA, Bier P, Hoatlin M, Pals G, de Winter JP, Wang W, Joenje H
Nat Genet 2004 Nov;36(11):1219-24. Epub 2004 Oct 24 doi: 10.1038/ng1458. PMID: 15502827

Diagnosis

Umaña LA, Magoulas P, Bi W, Bacino CA
Am J Med Genet A 2011 Dec;155A(12):3071-4. Epub 2011 Nov 3 doi: 10.1002/ajmg.a.34296. PMID: 22052692

Prognosis

Umaña LA, Magoulas P, Bi W, Bacino CA
Am J Med Genet A 2011 Dec;155A(12):3071-4. Epub 2011 Nov 3 doi: 10.1002/ajmg.a.34296. PMID: 22052692

Clinical prediction guides

Umaña LA, Magoulas P, Bi W, Bacino CA
Am J Med Genet A 2011 Dec;155A(12):3071-4. Epub 2011 Nov 3 doi: 10.1002/ajmg.a.34296. PMID: 22052692

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