In most cases of holoprosencephaly, the malformations are so severe that babies die before birth. Holoprosencephaly is a disorder caused by the failure of the prosencephalon (the embryonic forebrain) to sufficiently divide into the double lobes of the cerebral hemispheres. In older children, surgical repair of cleft lip and/or palate may be indicated. The result is a single-lobed brain structure and severe skull and facial defects. An endocrinology evaluation should be performed to assess for pituitary abnormalities. Hydrocephalus is common, particularly when a dorsal cyst is present. HPE can be seen in association with trisomy 13, trisomy 18, or triploidy. However, recent genetic studies have argued against this hypothesis. Neurologically, HPE is classified by aberrant cleavage of the embryonic forebrain. Holoprosencephaly includes a broad spectrum of defects, all based on defective formation of the forebrain (prosencephalon) and structures whose normal formation depends on influences from the forebrain. Children with HPE may experience a variety of medical and neurologic problems. Alobar Holoproencephaly is when the brain does not divided at all. Approximately 10% of individuals with holoprosencephaly have defects in cholesterol biosynthesis. Analysis of genotype-phenotype correlations in human holoprosencephaly. enable_page_level_ads: true The degree of delay is variable, correlating with the severity of the brain malformation, but tends to be severe. About one fourth of patients have some degree of midbrain nonseparation. It is possible to diagnose in utero. Feeding difficulties may be a major problem in children with holoprosencephaly. Children with diabetes insipidus need careful monitoring of fluid and electrolyte intake. Gastrostomy tubes often are necessary to address the complex management issues of ensuring adequate calories related to feeding dysfunction and delivery of adequate free water necessary for management of diabetes insipidus. Also, HPE is seen in Smith-Lemli-Opitz syndrome, which is due to a defect in 7-dehydrocholesterol reductase, the final enzyme in cholesterol synthesis. Cebocephaly, another facial anomaly, is characterized by a small, flattened nose with a single nostril situated below incomplete or underdeveloped closely-set eyes. If seizures develop, the possibility of acute reactive seizures should be evaluated for and a serum sodium level checked. Holoprosencephaly is a disorder caused by the failure of the prosencephalon (the embryonic forebrain) to sufficiently divide into the double lobes of the cerebral hemispheres. Figure 4. Holoprosencephaly is a dramatic central nervous system malformation highlighted by a partial or complete failure of the brain to separate into right and left hemispheres, forming a continuum of cortex and other structures across the midline. Height, weight, and head circumference should be measured during health maintenance evaluations. Although these models can be useful for studying the molecular mechanism of the condition, it is important to recognize that they do not reliably reconstruct the genetic architecture of human HPE due to the genetic complexities associated with the human genome. The hypothalamus and lentiform nuclei are normally separated; however, the caudate nuclei and the thalami remain incompletely separated. Screening for other endocrine abnormalities should be considered, including assays of cortisol, thyroid-stimulating hormone, free thyroxine, and insulin-like growth factor-1 (IGF-1). Approximately half of the children with HPE have epilepsy, and the likelihood of developing seizures does not correlate with the severity of the brain malformation. Most children with holoprosencephaly have cerebral palsy. Approximately 30% to 50% of live births with HPE have chromosomal abnormalities, but this is likely an overestimation based on underreporting of milder cases. Stashinko EE, Clegg NJ, Kammann HA et al. Holoprosencephaly is a disorder caused by the failure of the prosencephalon (the embryonic forebrain) to sufficiently divide into the double lobes of the cerebral hemispheres. Solomon BD, Lacbawan F, Mercier S, Clegg NJ, Delgado MR, Rosenbaum K, Dubourg C, David V, Olney AH, Wehner LE, Hehr U, Bale S, Paulussen A, Smeets HJ, Hardisty E, Tylki-Szymanska A, Pronicka E, Clemens M, McPherson E, Hennekam RC, Hahn J, Stashinko E, Levey E, Wieczorek D, Roeder E, Schell-Apacik CC, Booth CW, Thomas RL, Kenwrick S, Keaton A, Balog JZ, Hadley D, Zhou N, Long R, Velez JI, Pineda-Alvarez DE, Odent S, Roessler E, Muenke M. Mutations in ZIC2 in Human Holoprosencephaly: description of a novel ZIC2-specific phenotype and comprehensive analysis of 157 individuals. Orioli IM, Castilla EE. Heterozygous mutations in the homeodomain containing transcription factor Six3 is the third most common defect in HPE patients (Wallis et al., 1999). HPE is characterized by extreme intrafamilial variability. Cause HPE via interference with the holoprosencephaly spectrum of the brain, resulting in holoprosencephaly ranges from that. 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