Holoprosencephaly (HPE) is a common developmental anomaly of the human forebrain and midface where the cerebral hemispheres fail to separate into distinct left and right halves. We have previously reported haploinsufficiency for Sonic Hedgehog ( SHH ) as a cause for HPE. We have now performed mutational analysis of the complete coding region and intron-exon junctions of the SHH gene in 344 unrelated affected individuals. Herein, we describe 13 additional unrelated affected individuals with SHH mutations, including nonsense and missense mutations, deletions and an insertion. These mutations occur throughout the extent of the gene. No specific genotype-phenotype association is evident based on the correlation of the type or position of the mutations. In conjunction with our previous studies, we have identified a total of 23 mutations in 344 unrelated cases of HPE. They account for 14 cases of familial HPE and nine cases of sporadic HPE. Mutations in SHH were detected in 10 of 27 (37%) families showing autosomal dominant transmission of the HPE spectrum, based on structural anomalies. Interestingly, three of the patients with an SHH mutation also had abnormalities in another gene that is expressed during forebrain development. We suggest that the interactions of multiple gene products and/or environmental elements may determine the final phenotypic outcome for a given individual and that variations among these factors may cause the wide variability in the clinical features seen in HPE.

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without dysmorphic features had deletion 22q11. Conotruncal heart defects were the most common CVMs, often presenting in association with additional anomalies in four areas of the cardiovascular system: (1) the aortic arch can be right sided, cervical, double, and the subclavian artery can be aberrant, (2) the pulmonary arteries can present discontinuity, diffuse hypoplasia, discrete stenosis, defect of arborization and major aortopulmonary collateral arteries (MAPCA), (3) the infundibular septum can be malaligned, hypoplastic, or absent, (4) the semilunar valves can be bicuspid, severely dysplastic, insufficient, or stenotic. Conclusion: In subjects with deletion 22q11 CVM is virtually always associated with one or more noncardiac anomalies. Deletion 22q11 is exceptionally rare in children with nonsyndromic CVMs. Specific patterns of CVMs are observed in patients with deletion 22q11, including (1) anomalies of the aortic arch, (2) anomalies of the pulmonary arteries and of the pulmonary blood supply, (3) defects of the infundibular septum, (4) malformations of the semilunar valves. These additional CVMs may influence the surgical treatment of these patients. Genetics in Medicine, 2001:3(1):45-48.

This study reconfirms a high prevalence of celiac disease in Down syndrome. However, the diagnostic delay, the detection of atypical symptoms or silent form in one third of the cases, and the increased incidence of autoimmune disorders suggest the need for the screening of celiac disease in all Down syndrome patients.