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Holoprosencephaly 7(HPE7)

MedGen UID:
372134
Concept ID:
C1835820
Disease or Syndrome
Synonym: HPE7
 
Gene (location): PTCH1 (9q22.32)
 
Monarch Initiative: MONDO:0012562
OMIM®: 610828

Definition

Holoprosencephaly (HPE) is the most commonly occurring congenital structural forebrain anomaly in humans. HPE is associated with mental retardation and craniofacial malformations. Considerable heterogeneity in the genetic causes of HPE has been demonstrated (Ming et al., 2002). For general phenotypic information and a discussion of genetic heterogeneity of holoprosencephaly, see HPE1 (236100). [from OMIM]

Clinical features

From HPO
Macrotia
MedGen UID:
488785
Concept ID:
C0152421
Congenital Abnormality
Median longitudinal ear length greater than two standard deviations above the mean and median ear width greater than two standard deviations above the mean (objective); or, apparent increase in length and width of the pinna (subjective).
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.
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.
Holoprosencephaly sequence
MedGen UID:
38214
Concept ID:
C0079541
Congenital Abnormality
Nonsyndromic holoprosencephaly is an abnormality of brain development that also affects the head and face. Normally, the brain divides into two halves (hemispheres) during early development. Holoprosencephaly occurs when the brain fails to divide properly into the right and left hemispheres. This condition is called nonsyndromic to distinguish it from other types of holoprosencephaly caused by genetic syndromes, chromosome abnormalities, or substances that cause birth defects (teratogens). The severity of nonsyndromic holoprosencephaly varies widely among affected individuals, even within the same family.\n\nNonsyndromic holoprosencephaly can be grouped into four types according to the degree of brain division. From most to least severe, the types are known as alobar, semi-lobar, lobar, and middle interhemispheric variant (MIHV). In the most severe forms of nonsyndromic holoprosencephaly, the brain does not divide at all. These affected individuals have one central eye (cyclopia) and a tubular nasal structure (proboscis) located above the eye. Most babies with severe nonsyndromic holoprosencephaly die before birth or soon after. In the less severe forms, the brain is partially divided and the eyes are usually set close together (hypotelorism). The life expectancy of these affected individuals varies depending on the severity of symptoms.\n\nPeople with nonsyndromic holoprosencephaly often have a small head (microcephaly), although they can develop a buildup of fluid in the brain (hydrocephalus) that causes increased head size (macrocephaly). Other features may include an opening in the roof of the mouth (cleft palate) with or without a split in the upper lip (cleft lip), one central front tooth instead of two (a single maxillary central incisor), and a flat nasal bridge. The eyeballs may be abnormally small (microphthalmia) or absent (anophthalmia).\n\nSome individuals with nonsyndromic holoprosencephaly have a distinctive pattern of facial features, including a narrowing of the head at the temples, outside corners of the eyes that point upward (upslanting palpebral fissures), large ears, a short nose with upturned nostrils, and a broad and deep space between the nose and mouth (philtrum). In general, the severity of facial features is directly related to the severity of the brain abnormalities. However, individuals with mildly affected facial features can have severe brain abnormalities. Some people do not have apparent structural brain abnormalities but have some of the facial features associated with this condition. These individuals are considered to have a form of the disorder known as microform holoprosencephaly and are typically identified after the birth of a severely affected family member.\n\nMost people with nonsyndromic holoprosencephaly have developmental delay and intellectual disability. Affected individuals also frequently have a malfunctioning pituitary gland, which is a gland located at the base of the brain that produces several hormones. Because pituitary dysfunction leads to the partial or complete absence of these hormones, it can cause a variety of disorders. Most commonly, people with nonsyndromic holoprosencephaly and pituitary dysfunction develop diabetes insipidus, a condition that disrupts the balance between fluid intake and urine excretion. Dysfunction in other parts of the brain can cause seizures, feeding difficulties, and problems regulating body temperature, heart rate, and breathing. The sense of smell may be diminished (hyposmia) or completely absent (anosmia) if the part of the brain that processes smells is underdeveloped or missing.
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.
Panhypopituitarism
MedGen UID:
69171
Concept ID:
C0242343
Disease or Syndrome
A pituitary functional deficit affecting all the anterior pituitary hormones (growth hormone, thyroid-stimulating hormone, follicle-stimulating hormone, luteinizing hormone, adrenocorticotropic hormone, and prolactin).
Lobar holoprosencephaly
MedGen UID:
96559
Concept ID:
C0431362
Congenital Abnormality
A type of holoprosencephaly in which most of the right and left cerebral hemispheres and lateral ventricles are separated but the most rostral aspect of the telencephalon, the frontal lobes, are fused, especially ventrally.
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.
Partial agenesis of the corpus callosum
MedGen UID:
98127
Concept ID:
C0431368
Congenital Abnormality
A partial failure of the development of the corpus callosum.
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.
Fusion of the left and right thalami
MedGen UID:
331859
Concept ID:
C1834930
Finding
A developmental defect characterized by fusion of the left and right halves of the thalamus.
Hypoplasia of the brainstem
MedGen UID:
334226
Concept ID:
C1842688
Finding
Underdevelopment of the brainstem.
Occipital meningocele
MedGen UID:
336389
Concept ID:
C1848652
Disease or Syndrome
A herniation of meninges through a congenital bone defect in the skull in the occipital region.
Frontal bossing
MedGen UID:
67453
Concept ID:
C0221354
Congenital Abnormality
Bilateral bulging of the lateral frontal bone prominences with relative sparing of the midline.
Congenital omphalocele
MedGen UID:
162756
Concept ID:
C0795690
Congenital Abnormality
An omphalocele is an abdominal wall defect limited to an open umbilical ring, and is characterized by the herniation of membrane-covered internal organs into the open base of the umbilical cord. Omphalocele is distinguished from gastroschisis (230750), in which the abdominal wall defect is located laterally to a normally closed umbilical ring with herniation of organs that are uncovered by membranes (summary by Bugge, 2010). On the basis of clinical manifestations, epidemiologic characteristics, and the presence of additional malformations, Yang et al. (1992) concluded that omphalocele and gastroschisis are casually and pathogenetically distinct abdominal wall defects. Omphalocele can be a feature of genetic disorders, such as Beckwith-Wiedemann syndrome (130650) and the Shprintzen-Goldberg syndrome (182210).
Flat occiput
MedGen UID:
332439
Concept ID:
C1837402
Finding
Reduced convexity of the occiput (posterior part of skull).
Parietal bossing
MedGen UID:
347377
Concept ID:
C1857126
Finding
Parietal bossing is a marked prominence in the parietal region.
Cranial asymmetry
MedGen UID:
348059
Concept ID:
C1860245
Finding
Asymmetry of the bones of the skull.
Shallow orbits
MedGen UID:
351328
Concept ID:
C1865244
Finding
Reduced depth of the orbits associated with prominent-appearing ocular globes.
Macrocephaly
MedGen UID:
745757
Concept ID:
C2243051
Finding
Occipitofrontal (head) circumference greater than 97th centile compared to appropriate, age matched, sex-matched normal standards. Alternatively, a apparently increased size of the cranium.
Hypoplasia of the premaxilla
MedGen UID:
866508
Concept ID:
C4020770
Finding
An abnormality of the premaxilla (the embryonic structure that forms the anterior part of the maxilla) causing it to appear relatively small in size compared to the other parts of the maxilla or other facial structures.
Absent nasal septal cartilage
MedGen UID:
867277
Concept ID:
C4021638
Anatomical Abnormality
Lack of the cartilage of the nasal septum.
Microcephaly
MedGen UID:
1644158
Concept ID:
C4551563
Finding
Head circumference below 2 standard deviations below the mean for age and gender.
Bifid nose
MedGen UID:
66379
Concept ID:
C0221363
Congenital Abnormality
Visually assessable vertical indentation, cleft, or depression of the nasal bridge, ridge and tip.
Bilateral cleft lip
MedGen UID:
451046
Concept ID:
C0392005
Congenital Abnormality
A non-midline cleft of the upper lip on the left and right sides.
Unilateral cleft lip
MedGen UID:
451047
Concept ID:
C0392006
Congenital Abnormality
A non-midline cleft of the upper lip on one side only.
Upslanted palpebral fissure
MedGen UID:
98390
Concept ID:
C0423109
Finding
The palpebral fissure inclination is more than two standard deviations above the mean for age (objective); or, the inclination of the palpebral fissure is greater than typical for age.
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.
Wide nasal bridge
MedGen UID:
341441
Concept ID:
C1849367
Finding
Increased breadth of the nasal bridge (and with it, the nasal root).
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.
Flat face
MedGen UID:
342829
Concept ID:
C1853241
Finding
Absence of concavity or convexity of the face when viewed in profile.
Midface retrusion
MedGen UID:
339938
Concept ID:
C1853242
Anatomical Abnormality
Posterior positions and/or vertical shortening of the infraorbital and perialar regions, or increased concavity of the face and/or reduced nasolabial angle.
Short nose
MedGen UID:
343052
Concept ID:
C1854114
Finding
Distance from nasion to subnasale more than two standard deviations below the mean, or alternatively, an apparently decreased length from the nasal root to the nasal tip.
Broad face
MedGen UID:
349223
Concept ID:
C1859680
Finding
Bizygomatic (upper face) and bigonial (lower face) width greater than 2 standard deviations above the mean (objective); or an apparent increase in the width of the face (subjective).
Depressed nasal tip
MedGen UID:
347214
Concept ID:
C1859717
Finding
Decreased distance from the nasal tip to the nasal base.
Hypoplastic nasal septum
MedGen UID:
348327
Concept ID:
C1861328
Finding
Underdevelopment of the nasal septum.
Underdeveloped supraorbital ridges
MedGen UID:
349384
Concept ID:
C1861869
Congenital Abnormality
Flatness of the supraorbital portion of the frontal bones.
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).
Bilateral cleft palate
MedGen UID:
765998
Concept ID:
C3553084
Finding
Nonmidline cleft palate on the left and right sides.
Unilateral cleft palate
MedGen UID:
867754
Concept ID:
C4022143
Congenital Abnormality
Flat nasal alae
MedGen UID:
869333
Concept ID:
C4023759
Finding
An abnormal degree of flatness of the Ala of nose, which can be defined as a reduced nasal elevation index (lateral depth of the nose from the tip of the nose to the insertion of the nasal ala in the cheek x 100 divided by the side-to-side breadth of the nasal alae).
Midline defect of the nose
MedGen UID:
870948
Concept ID:
C4025411
Anatomical Abnormality
This term groups together three conditions that presumably represent different degrees of severity of a midline defect of the nose or nasal tip.
Synophrys
MedGen UID:
98132
Concept ID:
C0431447
Congenital Abnormality
Meeting of the medial eyebrows in the midline.
Hypertelorism
MedGen UID:
9373
Concept ID:
C0020534
Finding
Although hypertelorism means an excessive distance between any paired organs (e.g., the nipples), the use of the word has come to be confined to ocular hypertelorism. Hypertelorism occurs as an isolated feature and is also a feature of many syndromes, e.g., Opitz G syndrome (see 300000), Greig cephalopolysyndactyly (175700), and Noonan syndrome (163950) (summary by Cohen et al., 1995).
Microphthalmia
MedGen UID:
10033
Concept ID:
C0026010
Congenital Abnormality
Microphthalmia is an eye abnormality that arises before birth. In this condition, one or both eyeballs are abnormally small. In some affected individuals, the eyeball may appear to be completely missing; however, even in these cases some remaining eye tissue is generally present. Such severe microphthalmia should be distinguished from another condition called anophthalmia, in which no eyeball forms at all. However, the terms anophthalmia and severe microphthalmia are often used interchangeably. Microphthalmia may or may not result in significant vision loss.\n\nPeople with microphthalmia may also have a condition called coloboma. Colobomas are missing pieces of tissue in structures that form the eye. They may appear as notches or gaps in the colored part of the eye called the iris; the retina, which is the specialized light-sensitive tissue that lines the back of the eye; the blood vessel layer under the retina called the choroid; or in the optic nerves, which carry information from the eyes to the brain. Colobomas may be present in one or both eyes and, depending on their size and location, can affect a person's vision.\n\nPeople with microphthalmia may also have other eye abnormalities, including clouding of the lens of the eye (cataract) and a narrowed opening of the eye (narrowed palpebral fissure). Additionally, affected individuals may have an abnormality called microcornea, in which the clear front covering of the eye (cornea) is small and abnormally curved.\n\nBetween one-third and one-half of affected individuals have microphthalmia as part of a syndrome that affects other organs and tissues in the body. These forms of the condition are described as syndromic. When microphthalmia occurs by itself, it is described as nonsyndromic or isolated.
Iris coloboma
MedGen UID:
116097
Concept ID:
C0240063
Anatomical Abnormality
A coloboma of the iris.
Hypotelorism
MedGen UID:
96107
Concept ID:
C0424711
Finding
Interpupillary distance less than 2 SD below the mean (alternatively, the appearance of an decreased interpupillary distance or closely spaced eyes).
Bilateral microphthalmos
MedGen UID:
334420
Concept ID:
C1843496
Congenital Abnormality
A developmental anomaly characterized by abnormal smallness of both eyes.

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Bardi F, Bergman JEH, Siemensma-Mühlenberg N, Elvan-Taşpınar A, de Walle HEK, Bakker MK
Paediatr Perinat Epidemiol 2022 Nov;36(6):804-814. Epub 2022 Jul 12 doi: 10.1111/ppe.12914. PMID: 35821640Free PMC Article
Krab LC, Marcos-Alcalde I, Assaf M, Balasubramanian M, Andersen JB, Bisgaard AM, Fitzpatrick DR, Gudmundsson S, Huisman SA, Kalayci T, Maas SM, Martinez F, McKee S, Menke LA, Mulder PA, Murch OD, Parker M, Pie J, Ramos FJ, Rieubland C, Rosenfeld Mokry JA, Scarano E, Shinawi M, Gómez-Puertas P, Tümer Z, Hennekam RC
Hum Genet 2020 May;139(5):575-592. Epub 2020 Mar 19 doi: 10.1007/s00439-020-02138-2. PMID: 32193685Free PMC Article
Jauniaux E, Brown R, Snijders RJ, Noble P, Nicolaides KH
Am J Obstet Gynecol 1997 Mar;176(3):550-4. doi: 10.1016/s0002-9378(97)70546-5. PMID: 9077605

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