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Holoprosencephaly 13, X-linked(HPE13)

MedGen UID:
1714826
Concept ID:
C5393308
Disease or Syndrome
Synonyms: HOLOPROSENCEPHALY 13, X-LINKED; HPE13
 
Gene (location): STAG2 (Xq25)
 
Monarch Initiative: MONDO:0026763
OMIM®: 301043

Definition

X-linked holoprosencephaly-13 (HPE13) is a neurologic disorder characterized by midline developmental defects that mainly affect the brain and craniofacial structure. The severity and manifestations are variable: some patients may have full alobar HPE with cyclopia, whereas others have semilobar HPE or septooptic dysplasia. Dysmorphic features include microcephaly, hypotelorism, low-set ears, micrognathia, and cleft lip/palate. Patients with a more severe phenotype may die in the newborn period, whereas those with a less severe phenotype show global developmental delay. Additional variable features include congenital heart defects and vertebral anomalies. Phenotypic variability may be related to the type of mutation, X-inactivation status, and possible incomplete penetrance. The STAG2 protein is part of the multiprotein cohesin complex involved in chromatid cohesion during DNA replication and transcriptional regulation; HPE13 can thus be classified as a 'cohesinopathy' (summary by Kruszka et al., 2019). For a discussion of genetic heterogeneity of holoprosencephaly, see HPE1 (236100). [from OMIM]

Clinical features

From HPO
Double outlet right ventricle
MedGen UID:
41649
Concept ID:
C0013069
Congenital Abnormality
Double outlet right ventricle (DORV) is a type of ventriculoarterial connection in which both great vessels arise entirely or predominantly from the right ventricle.
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.
Patent foramen ovale
MedGen UID:
8891
Concept ID:
C0016522
Congenital Abnormality
Failure of the foramen ovale to seal postnatally, leaving a potential conduit between the left and right cardiac atria.
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.
Hypoplastic left heart syndrome
MedGen UID:
57746
Concept ID:
C0152101
Disease or Syndrome
Critical congenital heart disease (CCHD) is a term that refers to a group of serious heart defects that are present from birth. These abnormalities result from problems with the formation of one or more parts of the heart during the early stages of embryonic development. CCHD prevents the heart from pumping blood effectively or reduces the amount of oxygen in the blood. As a result, organs and tissues throughout the body do not receive enough oxygen, which can lead to organ damage and life-threatening complications. Individuals with CCHD usually require surgery soon after birth.\n\nEach of the heart defects associated with CCHD affects the flow of blood into, out of, or through the heart. Some of the heart defects involve structures within the heart itself, such as the two lower chambers of the heart (the ventricles) or the valves that control blood flow through the heart. Others affect the structure of the large blood vessels leading into and out of the heart (including the aorta and pulmonary artery). Still others involve a combination of these structural abnormalities.\n\nAlthough babies with CCHD may appear healthy for the first few hours or days of life, signs and symptoms soon become apparent. These can include an abnormal heart sound during a heartbeat (heart murmur), rapid breathing (tachypnea), low blood pressure (hypotension), low levels of oxygen in the blood (hypoxemia), and a blue or purple tint to the skin caused by a shortage of oxygen (cyanosis). If untreated, CCHD can lead to shock, coma, and death. However, most people with CCHD now survive past infancy due to improvements in early detection, diagnosis, and treatment.\n\nSome people with treated CCHD have few related health problems later in life. However, long-term effects of CCHD can include delayed development and reduced stamina during exercise. Adults with these heart defects have an increased risk of abnormal heart rhythms, heart failure, sudden cardiac arrest, stroke, and premature death.\n\nPeople with CCHD have one or more specific heart defects. The heart defects classified as CCHD include coarctation of the aorta, double-outlet right ventricle, D-transposition of the great arteries, Ebstein anomaly, hypoplastic left heart syndrome, interrupted aortic arch, pulmonary atresia with intact septum, single ventricle, total anomalous pulmonary venous connection, tetralogy of Fallot, tricuspid atresia, and truncus arteriosus.
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.
Gastroesophageal reflux
MedGen UID:
1368658
Concept ID:
C4317146
Finding
A condition in which the stomach contents leak backwards from the stomach into the esophagus through the lower esophageal sphincter.
Microtia
MedGen UID:
57535
Concept ID:
C0152423
Congenital Abnormality
Underdevelopment of the external ear.
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.
Hearing impairment
MedGen UID:
235586
Concept ID:
C1384666
Disease or Syndrome
A decreased magnitude of the sensory perception of sound.
Seizure
MedGen UID:
20693
Concept ID:
C0036572
Sign or Symptom
A seizure is an intermittent abnormality of nervous system physiology characterized by a transient occurrence of signs and/or symptoms due to abnormal excessive or synchronous neuronal activity in the brain.
Corpus callosum, agenesis of
MedGen UID:
104498
Concept ID:
C0175754
Congenital Abnormality
The corpus callosum is the largest fiber tract in the central nervous system and the major interhemispheric fiber bundle in the brain. Formation of the corpus callosum begins as early as 6 weeks' gestation, with the first fibers crossing the midline at 11 to 12 weeks' gestation, and completion of the basic shape by age 18 to 20 weeks (Schell-Apacik et al., 2008). Agenesis of the corpus callosum (ACC) is one of the most frequent malformations in brain with a reported incidence ranging between 0.5 and 70 in 10,000 births. ACC is a clinically and genetically heterogeneous condition, which can be observed either as an isolated condition or as a manifestation in the context of a congenital syndrome (see MOLECULAR GENETICS and Dobyns, 1996). Also see mirror movements-1 and/or agenesis of the corpus callosum (MRMV1; 157600). Schell-Apacik et al. (2008) noted that there is confusion in the literature regarding radiologic terminology concerning partial absence of the corpus callosum, where various designations have been used, including hypogenesis, hypoplasia, partial agenesis, or dysgenesis.
Septo-optic dysplasia sequence
MedGen UID:
90926
Concept ID:
C0338503
Disease or Syndrome
Septooptic dysplasia is a clinically heterogeneous disorder loosely defined by any combination of optic nerve hypoplasia, pituitary gland hypoplasia, and midline abnormalities of the brain, including absence of the corpus callosum and septum pellucidum (Dattani et al., 1998). The diagnosis of this rare congenital anomaly is made when 2 or more features of the classic triad are present. Approximately 30% of patients have complete manifestations, 62% display hypopituitarism, and 60% have an absent septum pellucidum. The disorder is equally prevalent in males and females and is more common in infants born to younger mothers, with a reported incidence of 1 in 10,000 live births (summary by Webb and Dattani, 2010). Also see 516020.0012 for a form of septooptic dysplasia associated with cardiomyopathy and exercise intolerance.
Alobar holoprosencephaly
MedGen UID:
140909
Concept ID:
C0431363
Congenital Abnormality
A type of holoprosencephaly characterized by the presence of a single ventricle and no separation of the cerebral hemisphere. The single midline ventricle is often greatly enlarged.
Colpocephaly
MedGen UID:
98131
Concept ID:
C0431384
Congenital Abnormality
Colpocephaly is an anatomic finding in the brain manifested by occipital horns that are disproportionately enlarged in comparison with other parts of the lateral ventricles.
Global developmental delay
MedGen UID:
107838
Concept ID:
C0557874
Finding
A delay in the achievement of motor or mental milestones in the domains of development of a child, including motor skills, speech and language, cognitive skills, and social and emotional skills. This term should only be used to describe children younger than five years of age.
Semilobar holoprosencephaly
MedGen UID:
199694
Concept ID:
C0751617
Congenital Abnormality
A type of holoprosencephaly in which the left and right frontal and parietal lobes are fused and the interhemispheric fissure is only present posteriorly.
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.
Micrognathia
MedGen UID:
44428
Concept ID:
C0025990
Congenital Abnormality
Developmental hypoplasia of the mandible.
Thoracic hemivertebrae
MedGen UID:
98142
Concept ID:
C0432152
Congenital Abnormality
Absence of one half of the vertebral body in the thoracic spine.
Vertebral clefting
MedGen UID:
344586
Concept ID:
C1855828
Finding
Schisis (cleft or cleavage) of vertebral bodies.
Microcephaly
MedGen UID:
1644158
Concept ID:
C4551563
Finding
Head circumference below 2 standard deviations below the mean for age and gender.
Butterfly vertebrae
MedGen UID:
1744309
Concept ID:
C5438458
Congenital Abnormality
A butterfly vertebra (sagittal cleft vertebra or anterior rachischisis) is a sagittal defect in the vertebral body caused by failure of fusion of the two lateral chondrification centers during embryogenesis. The name is based on the appearance of the two hemivertebrae emerging as butterfly wings from the central cleft on x-ray.
Aplasia of the nose
MedGen UID:
120555
Concept ID:
C0265740
Congenital Abnormality
Complete absence of all nasal structures.
Submucous cleft hard palate
MedGen UID:
98472
Concept ID:
C0432103
Congenital Abnormality
Hard-palate submucous clefts are characterized by bony defects in the midline of the bony palate that are covered by the mucous membrane of the roof of the mouth. It may be possible to detect a submucous cleft hard palate upon palpation as a notch in the bony palate.
Solitary median maxillary central incisor syndrome
MedGen UID:
326686
Concept ID:
C1840235
Congenital Abnormality
A single maxillary central incisor positioned in the midline with morphological symmetry of the crown and bordered by lateral incisors.
Median cleft upper lip
MedGen UID:
342454
Concept ID:
C1850256
Congenital Abnormality
A type of cleft lip presenting as a midline (median) gap in the upper lip.
Median cleft palate
MedGen UID:
340670
Concept ID:
C1850968
Congenital Abnormality
Cleft palate of the midline of the palate.
Cleft palate
MedGen UID:
756015
Concept ID:
C2981150
Congenital Abnormality
Cleft palate is a developmental defect of the palate resulting from a failure of fusion of the palatine processes and manifesting as a separation of the roof of the mouth (soft and hard palate).
Holoprosencephaly 1
MedGen UID:
78617
Concept ID:
C0266667
Congenital Abnormality
Holoprosencephaly (HPE) is the most common structural malformation of the human forebrain and occurs after failed or abbreviated midline cleavage of the developing brain during the third and fourth weeks of gestation. HPE occurs in up to 1 in 250 gestations, but only 1 in 8,000 live births (Lacbawan et al., 2009). Classically, 3 degrees of severity defined by the extent of brain malformation have been described. In the most severe form, 'alobar HPE,' there is a single ventricle and no interhemispheric fissure. The olfactory bulbs and tracts and the corpus callosum are typically absent. In 'semilobar HPE,' the most common type of HPE in neonates who survive, there is partial cortical separation with rudimentary cerebral hemispheres and a single ventricle. In 'lobar HPE,' the ventricles are separated, but there is incomplete frontal cortical separation (Corsello et al., 1990). An additional milder form, called 'middle interhemispheric variant' (MIHV) has also been delineated, in which the posterior frontal and parietal lobes are incompletely separated and the corpus callosum may be hypoplastic (Lacbawan et al., 2009). Finally, microforms of HPE include a single maxillary median incisor or hypotelorism without the typical brain malformations (summary by Mercier et al., 2011). Cohen (2001) discussed problems in the definition of holoprosencephaly, which can be viewed from 2 different perspectives: anatomic (fixed) and genetic (broad). When the main interest is description, the anatomic perspective is appropriate. In genetic perspective, a fixed definition of holoprosencephaly is not appropriate because the same mutational cause may result in either holoprosencephaly or some microform of holoprosencephaly. Cohen (2001) concluded that both fixed and broad definitions are equally valid and depend on context. Munke (1989) provided an extensive review of the etiology and pathogenesis of holoprosencephaly, emphasizing heterogeneity. See also schizencephaly (269160), which may be part of the phenotypic spectrum of HPE. Genetic Heterogeneity of Holoprosencephaly Several loci for holoprosencephaly have been mapped to specific chromosomal sites and the molecular defects in some cases of HPE have been identified. Holoprosencephaly-1 (HPE1) maps to chromosome 21q22. See also HPE2 (157170), caused by mutation in the SIX3 gene (603714) on 2p21; HPE3 (142945), caused by mutation in the SHH gene (600725) on 7q36; HPE4 (142946), caused by mutation in the TGIF gene (602630) on 18p11; HPE5 (609637), caused by mutation in the ZIC2 gene (603073) on 13q32; HPE6 (605934), mapped to 2q37; HPE7 (610828), caused by mutation in the PTCH1 gene (601309) on 9q22; HPE8 (609408), mapped to 14q13; HPE9 (610829), caused by mutation in the GLI2 gene (165230) on 2q14; HPE10 (612530), mapped to 1q41-q42; HPE11 (614226), caused by mutation in the CDON gene (608707) on 11q24; HPE12 (618500), caused by mutation in the CNOT1 gene (604917) on 16q21; HPE13 (301043), caused by mutation in the STAG2 gene (300826) on Xq25; and HPE14 (619895), caused by mutation in the PLCH1 gene (612835) on 3q25. Wallis and Muenke (2000) gave an overview of mutations in holoprosencephaly. They indicated that at least 12 different loci had been associated with HPE. Mutations in genes involved in the multiprotein cohesin complex, including STAG2, have been shown to be involved in midline brain defects such as HPE. Mutations in some of those genes cause Cornelia de Lange syndrome (CDLS; see 122470), and some patients with severe forms of CDLS may have midline brain defects. See, for example, CDLS2 (300590), CDLS3 (610759), and CDLS4 (614701).
Optic nerve hypoplasia
MedGen UID:
137901
Concept ID:
C0338502
Disease or Syndrome
Underdevelopment of the optic nerve.

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