Whole genomewide linkage screen for neural tube defects reveals regions of interest on chromosomes 7 and 10.

Neural tube defects (NTDs) are the second most common birth defects (1 in 1000 live births) in the world. Periconceptional maternal folate supplementation reduces NTD risk by 50-70%; however, studies of folate related and other developmental genes in humans have failed to definitively identify a major causal gene for NTD. The aetiology of NTDs remains unknown and both genetic and environmental factors are implicated. We present findings from a microsatellite based screen of 44 multiplex pedigrees ascertained through the NTD Collaborative Group. For the linkage analysis, we defined our phenotype narrowly by considering individuals with a lumbosacral level myelomeningocele as affected, then we expanded the phenotype to include all types of NTDs. Two point parametric analyses were performed using VITESSE and HOMOG. Multipoint parametric and nonparametric analyses were performed using ALLEGRO. Initial results identified chromosomes 7 and 10, both with maximum parametric multipoint lod scores (Mlod) >2.0. Chromosome 7 produced the highest score in the 24 cM interval between D7S3056 and D7S3051 (parametric Mlod 2.45; nonparametric Mlod 1.89). Further investigation demonstrated that results on chromosome 7 were being primarily driven by a single large pedigree (parametric Mlod 2.40). When this family was removed from analysis, chromosome 10 was the most interesting region, with a peak Mlod of 2.25 at D10S1731. Based on mouse human synteny, two candidate genes (Meox2, Twist1) were identified on chromosome 7. A review of public databases revealed three biologically plausible candidates (FGFR2, GFRA1, Pax2) on chromosome 10. The results from this screen provide valuable positional data for prioritisation of candidate gene assessment in future studies of NTDs.

Gastrointestinal abnormalities: a significant cause of feeding difficulties and failure to thrive in Brachmann-de Lange syndrome.

Gastroesophageal abnormalities occur with increased frequency in patients with Brachmann-de Lange syndrome (BDLS) and contribute to problems with feeding, emesis and failure to thrive. Comprehensive evaluation including longitudinal assessment of growth and development of 8 patients with BDLS was performed. Clinically significant feeding problems occurred in 6 of the 8 patients and the affected children were subsequently evaluated for gastrointestinal abnormalities. Findings in these patients included tracheal aspiration, esophageal dysmotility, gastroesophageal reflux, hiatal hernia, and esophagitis. Medical treatment was instituted where appropriate, and surgical treatment was performed if the problems did not resolve with medical treatment. Improvement in weight centiles occurred in all patients fed by nasogastric or feeding gastrostomy tube but only one patient appeared to experience increase in rate of linear growth. Careful monitoring of symptoms and growth parameters, and prompt institution of appropriate medical and surgical measures can improve the health and physical outcome of many patients with BDLS.

Glaucoma and findings simulating glaucoma in the Rubinstein-Taybi syndrome.

Information is reviewed on the ophthalmologic findings in 614 individuals with Rubinstein-Taybi syndrome (RTS). The data were collected from the world literature, from communication with colleagues and with families of individuals with RTS, and from personal observations. Particular emphasis is given in this article to the association of RTS with glaucoma and five other findings that may be confused with glaucoma (corneal lesions, megalocornea, colobomatous or cystic optic nerve, excavation of papilla, and large cup-to-disc ratio). A case report is presented including autopsy results on a 5-year-old black female with RTS, corneal lesions, colobomas of the optic nerves, and normal intraocular pressure.

Genetic studies in neural tube defects. NTD Collaborative Group.

Neural tube defects (NTD) are one of the most common birth defects and are caused by both environmental and genetic factors. The approach to identifying the genes predisposing to NTD, through linkage analysis and candidate gene analysis, is reviewed along with characteristics of a large, nationally ascertained cohort of families. Results from specific assessments of p53, PAX3 and MTHFR failed to suggest that these genes play a major role in NTD development in these families. Advances in genetic laboratory and statistical techniques have made this a prime opportunity for investigation into the causes of complex disorders, such as NTD. However, traditional approaches may prove to be challenging due to the difficulty of ascertaining samplable multiplex families.