Holoprosencephaly with Dandy-Walker cyst. Rare coexistence of two major malformations

Familial aplasia cutis congenita associated with mega-cisterna magna

Aplasia cutis congenita (ACC; MIM 107600) is a congenital skin disorder that manifests as localized absence of skin. Here we report a case of familial ACC and mega-cisterna magna. A female neonate was born with skin defects on the scalp. Brain magnetic resonance imaging demonstrated retrocerebellar space widening suggesting mega-cisterna magna. Her father also had a skin defect on the scalp at birth, and brain computed tomography of the father showed a cystic lesion over the right occipital lobe, similar to the patient's brain imaging. Karyotype 46,XX, t(6;18)(q23.2;q11.2) was identified on G-banded karyotype analysis of the patient and her father, after which whole exome sequencing was carried out, but this was thought to be a coincidental finding. This indicates that ACC may be associated with brain anomaly, although it is very rare.

Holoprosencephaly and ZIC2 microdeletions: novel clinical and epidemiological specificities delineated

Holoprosencephaly (HPE), the most common malformation of the human brain results from abnormal cleavage of the forebrain during the early embryonic developmental stages. The spectrum of malformations in HPE is wide, ranging from the classical cyclopia/proboscis to fairly asymptomatic forms [i.e. a single maxillary central incisor (SMCI)]. HPE may be caused by environmental or genetic factors. ZIC2 (13q32) was the second gene identified in which mutations cause HPE and recently a specific phenotype was ascribed to ZIC2-mutation HPE. Earlier, we reported a boy presenting HPE and deafness. Cytogenetic analyses were normal. Using array-comparative genomic hybridization (aCGH), we found a de novo 129 kb del(13)(q32) encompassing ZIC2 and ZIC5. There is no evidence for the involvement of ZIC5 in human diseases. We reviewed the literature for ZIC2-ZIC5 deletions and their involvement in neural tube defects (NTDs). Interestingly, we found evidence for a specific facial phenotype for ZIC2 gene deletion patients distinct from those with point mutations. In addition, based on the clinical data together with pathology, imaging and functional studies, we suggest an outline for a model explaining the genetic heterogeneity of ZIC2-ZIC5-associated NTDs and propose further studies for validation.

The ZIC gene family in development and disease

The human ZIC gene family is comprised of five members encoding zinc-finger transcription factors, which are the vertebrate homologs of the Drosophila odd-paired gene. Mutations in ZIC genes in humans have recently been implicated in a wide variety of congenital malformations, including Dandy-Walker malformation, holoprosencephaly, neural tube defects, and heterotaxy. Mutant analysis of these genes in mice has underscored the conserved developmental roles of these genes. Further, this analysis has begun to elucidate the molecular and developmental mechanisms underlying these important birth defects.

Partial deletions of the long arm of chromosome 13 associated with holoprosencephaly and the Dandy-Walker malformation

Two patients with partial deletions of the long arm of chromosome 13, del(13)(13q21-q34) and del(13)(13q22-q33), respectively, multiple congenital anomalies including holoprosencephaly (HPE) and the Dandy-Walker malformation (DWM) are described. The occurrence of HPE and the DWM in both of these patients suggests that, in addition to ZIC2, which is important for normal development of the forebrain, there is at least one other dosage-sensitive gene in 13q22-q33 that plays an important role in brain development. The DWM is anatomically and developmentally distinct from HPE. The presence of a DWM in each of these two patients with partial deletions of the long arm of chromosome 13 suggests that haploinsufficiency at a locus in 13q22-q33 may cause this anomaly. These findings suggest that microdeletions in 13q22-q33 may be found in a proportion of patients with an apparently isolated DWM. Therefore, careful high-resolution cytogenetic analysis (550 band level or greater) of 13q22-q33 may be considered in these patients. Furthermore, future molecular studies of this region may reveal candidate gene loci for the DWM.

Aplasia cutis congenita and associated disorders: an update

We present an update of disorders in which aplasia cutis congenita is a feature. Localization of the lesion, important other features, and possible etiology are tabulated. Disorders are classified as chromosomal, monogenic, teratological/exogenous, and unknown. Points of particular interest in history taking and examination of patients with aplasia cutis congenita are presented.

Familial Dandy-Walker malformation associated with macrocephaly, facial anomalies, developmental delay, and brain stem dysgenesis: prenatal diagnosis and postnatal outcome in brothers. A new syndrome?

Brothers are reported with an apparently new constellation of manifestations including Dandy-Walker complex (DWC), migrational brain disorder, macrocephaly, and facial anomalies. The first brother presented at birth, the second was detected prenatally with DWC and the pregnancy terminated. Fetal brain histopathology showed DWC associated with brainstem dysgenesis. Inheritance is likely autosomal or X-linked recessive. An extensive review of the differential diagnosis of DWC is provided.