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1.

HYPOGONADOTROPIC HYPOGONADISM 3 WITH OR WITHOUT ANOSMIA

MedGen UID:
763392
Concept ID:
C3550478
Disease or Syndrome
2.

Holoprosencephaly 1

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 21q22.3. HPE2 (157170), caused by mutation in the SIX3 gene (603714), maps to 2p21. HPE3 (142945), caused by mutation in the Sonic hedgehog gene (SHH; 600725), maps to 7q36. HPE4 (142946), caused by mutation in the TGIF gene (602630), maps to 18p11.3. HPE5 (609637), caused by mutation in the ZIC2 gene (603073), maps to 13q32. HPE6 (605934) maps to 2q37.1. HPE7 (610828), caused by mutation in the PTCH1 gene (601309), maps to 9q22.3. HPE8 (609408) maps to 14q13. HPE9 (610829), caused by mutation in the GLI2 gene (165230), maps to 2q14. HPE10 (612530) maps to 1q41-q42. HPE11 (614226) is caused by mutation in the CDON gene (608707) on chromosome 11q23-11q24. For associations pending confirmation, see MOLECULAR GENETICS. Wallis and Muenke (2000) gave an overview of mutations in holoprosencephaly. They indicated that at least 12 different loci had been associated with HPE. [from OMIM]

MedGen UID:
341060
Concept ID:
C1856096
Disease or Syndrome
3.

Alobar holoprosencephaly

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. [from HPO]

MedGen UID:
140909
Concept ID:
C0431363
Congenital Abnormality
4.

Hypogonadism with anosmia

Isolated gonadotropin-releasing hormone (GnRH) deficiency (IGD) is characterized by inappropriately low serum concentrations of the gonadotropins LH (luteinizing hormone) and FSH (follicle-stimulating hormone) in the setting of hypogonadism. IGD is associated with a normal sense of smell (normosmic IGD) in approximately 40% of affected individuals and an impaired sense of smell (Kallmann syndrome [KS]) in approximately 60%. IGD can first be apparent in infancy, adolescence, or adulthood. Infant boys with congenital (i.e., present at birth) IGD often have micropenis and cryptorchidism. Adolescents and adults with IGD have clinical evidence of hypogonadism and incomplete sexual maturation on physical examination. Adult males with IGD tend to have prepubertal testicular volume (i.e., <4 mL), absence of secondary sexual features (e.g., facial and axillary hair growth, deepening of the voice), decreased muscle mass, diminished libido, erectile dysfunction, and infertility. Adult females have little or no breast development and primary amenorrhea. Although skeletal maturation is delayed, the rate of linear growth is usually normal except for the absence of a distinct pubertal growth spurt. [from GeneReviews]

MedGen UID:
102469
Concept ID:
C0162809
Disease or Syndrome
5.

Cyclopia

Cyclopia is a congenital abnormality in which there is only one eye. That eye is centrally placed in the area normally occupied by the root of the nose. [from HPO]

MedGen UID:
78617
Concept ID:
C0266667
Congenital Abnormality
6.

Holoprosencephaly sequence

Holoprosencephaly (HPE) is a structural anomaly of the brain in which there is failed or incomplete separation of the forebrain early in gestation. Classic HPE encompasses a continuum of brain malformations including (in order of decreasing severity): alobar, semilobar, lobar, and middle interhemispheric variant (MIHV) type HPE; a septopreoptic type has also been described. Other CNS abnormalities not specific to HPE may also occur. HPE is accompanied by a spectrum of characteristic craniofacial anomalies in approximately 80% of individuals with HPE. Developmental delay is present in virtually all individuals with the HPE spectrum of CNS anomalies. Seizures and pituitary dysfunction are common. Most affected fetuses do not survive; severely affected children typically do not survive beyond early infancy, while a significant proportion of more mildly affected children survive past 12 months. Mildly manifesting individuals without appreciable brain anomalies on conventional neuroimaging may be described as having “microform” HPE. [from GeneReviews]

MedGen UID:
38214
Concept ID:
C0079541
Congenital Abnormality
7.

Arrhinencephaly

MedGen UID:
36258
Concept ID:
C0078982
Congenital Abnormality; Disease or Syndrome
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