holoprosencephaly


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holoprosencephaly

 [hol″o-pros″en-sef´ah-le]
a developmental anomaly consisting of failure of cleavage of the prechordal mesoderm with a deficit in the forebrain and midline facial development; in the severe form there may be cyclopia. It is sometimes associated with trisomy 13 syndrome.
The facial features in holoprosencephaly. The eyes are close together and there is a midline cleft lip. From Mueller and Young, 2001.

hol·o·pros·en·ceph·a·ly

(hol'ō-pros-en-sef'ă-lē),
Impaired midline cleavage of the embryonic forebrain resulting in a wide spectrum of facial features from cyclopia with proboscis above the single eye at the most severe form to ocular hypertelorism and single central upper incisor at the mildest form. This spectrum of disorders is associated with chromosomal aberrations involving chromosomes 2, 3, 7, 13, 18 and 21.
[holo- + G. prosō, forward, + enkephalos, brain]

holoprosencephaly

A disorder in which the developing forebrain fails to correctly separate into right and left hemispheres, which is accompanied by facial deformities.

Molecular pathology
Holoprosencephaly is attributed to mutations of the SHH gene.

hol·o·pros·en·ceph·a·ly

(hol'ō-pros-en-sef'ă-lē)
Failure of the forebrain or prosencephalon to divide into hemispheres or lobes; cyclopia occurs in the severest form. It is often accompanied by a deficit in midline facial development.
[holo- + G. prosō, forward, + enkephalos, brain]

hol·o·pros·en·ceph·a·ly

(hol'ō-pros-en-sef'ă-lē)
Failure of the forebrain or prosencephalon to divide into hemispheres or lobes; cyclopia occurs in the severest form.
[holo- + G. prosō, forward, + enkephalos, brain]
References in periodicals archive ?
The human brain and face: mechanisms of cranial, neurological and facial development revealed through malformations of holoprosencephaly, cyclopia and aberrations in chromosome 18.
Johnson and Bachman (32) published the first case of 18p deletion with holoprosencephaly. Gripp (33) identified the fourth gene, TGIF gene, responsible for the holoprosencephaly phenotype located on 18p at a distance of 3.5 Mb from the telomere.
Fetal ultrasound and echocardiography performed on the fetus of a 36-year-old woman during her first pregnancy within the 21st week of gestation revealed intrauterine growth retardation (IUGR), absent nasal bone, bilateral microphthalmia, holoprosencephaly, diaphragmatic hernia, atrioventricular septal defect, tricuspid atresia, and pulmonary hypoplasia.
Group VI: lateral proboscis with holoprosencephaly. The case reported here fits into group IV; except the eye and ocular adnexa, all were normal.
Prenatal diagnosis and molecular analysis of triploidy in a fetus with intrauterine growth restriction, relative macrocephaly and holoprosencephaly. Taiwan J Obstet Gynecol 2009;48(3):323-326.
A single case of holoprosencephaly, not noted on the prenatal ultrasound report, was identified during pathology examination; however, this case was unusual in that cervical dilation allowed the extraction of an intact specimen.
The anatomical recognition of this variant becomes important for the occurrence of saccular aneurysms, relatively common (13-71%), associated malformations (dysgenesis of the corpus callosum, lobar holoprosencephaly, septooptic dysplasia, porencephalic cysts, and arteriovenous malformations), and presence of bifrontal infarctions in case of occlusion [1].
Third group was of congenital malformations which include pachygyria, holoprosencephaly, dandy walker variant, hydrocephalus and agenesis of corpus callosum.
(2) Atypical signs reported in trisomy 9 patients include hemivertebra, (3) holoprosencephaly, (4) sex reversal, (5) an unexpectedly normal psychomotor development, (6) no evident external or internal congenital anomalies and congenital leukemia.
Indeed, megalin-deficient embryonic mice display abnormal formation of the forebrain and its derived structures, giving rise to a holoprosencephaly phenotype [29].
A brain scan showed that Aaron has holoprosencephaly, a condition in which the brain doesn't form.