A gene map of congenital malformations

A universal carrier test for the long tail of Mendelian disease

Mendelian disorders are individually rare but collectively common, forming a 'long tail' of genetic disease. A single highly accurate assay for this long tail would allow the scaling up of the Jewish community's successful campaign of population screening for Tay-Sachs disease to the general population, thereby improving millions of lives, greatly benefiting minority health and saving billions of dollars. This need has been addressed by designing a universal carrier test: a non-invasive, saliva-based assay for more than 100 Mendelian diseases across all major population groups. The test has been exhaustively validated with a median of 147 positive and 525 negative samples per variant, demonstrating a multiplex assay whose performance compares favourably with the previous standard of care, namely blood-based single-gene carrier tests. Because the test represents a dramatic reduction in the cost and complexity of large-scale population screening, an end to many preventable genetic diseases is now in sight. Moreover, given that the assay is inexpensive and requires only a saliva sample, it is now increasingly feasible to make carrier testing a routine part of preconception care.

Orofaciodigital syndrome type I in a patient with severe CNS defects

A female patient with orofaciodigital syndrome type I associated with pachygyria, heterotopic gray matter, interhemispheric cyst, agenesis of the corpus callosum, and a Dandy-Walker anomaly is reported. Because some of these defects have been described in patients with different types of orofaciodigital syndromes, we recommend caution when using neuroradiologic criteria to separate these syndromes. Given the severe spectrum of brain abnormalities displayed by our patient, and considering their similarity with the brain defects formerly described in other X-linked dominant conditions with male lethality localized to Xp22, the use of DNA probes from Xp22 is advised in identifying the gene(s) causing orofaciodigital syndrome type I.

Myocardial infarction resulting from coronary artery dissection in an adolescent with Ehlers-Danlos syndrome type IV due to a type III collagen mutation

Ehlers-Danlos syndrome encompasses a group of inherited disorders of connective tissue, some of which are characterised by abnormalities of collagen metabolism. The chromosomal location, identified genes and biochemical defects, inheritance pattern, and clinical features for the various known subtypes are outlined. Prenatal diagnosis is possible for types IV, VI, VIIA1, and VIIA2. An unusual presentation of type IV Ehlers-Danlos syndrome in a 16 year old boy with an anterior myocardial infarction resulting from dissection of the left anterior descending coronary artery is reported here. A clinical diagnosis of type IV Ehlers-Danlos syndrome was made subsequently and confirmed by the reduced production, impaired secretion, and abnormally slow electrophoretic migration of type III collagen, indicating an underlying mutation in the COL3A1 gene. This patient represents the first case of type IV Ehlers-Danlos syndrome with symptomatic coronary artery dissection.