We describe eight patients who have α thalassemia which cannot be accounted for the Mendelian inheritance of abnormal α globin genes. Apart from the hematologic abnormality, the other universal clinical finding is mild to moderate mental handicap; there is also a broad spectrum of associated dysmorphic features. Initial analysis of the α globin gene complex (which maps to chromosome band 16p13.3), demonstrated that the α thalassemia results from failure of the patient to inherit an α globin allele from one of the parents. Using a combined molecular and cytogenetic approach, we have extended this analysis to show that all of these patients have 16p deletions which are variable in extent but limited to the terminal band 16p13.3; in at least four cases the deletion results from unbalanced chromosome translocation, and hence aneuploidy of a second chromosome is also present. The relatively nonspecific clinical phenotype contrasts with the other currently known microdeletion syndromes; this may reflect ascertainment bias in the recognition of such syndromes. This work represents the first step in the characterization of a new microdeletion syndrome that is probably underdiagnosed at present.
|Original language||English (US)|
|Number of pages||15|
|Journal||American journal of human genetics|
|State||Published - 1990|
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