PROGRESSIVE DEFICIENCIES IN BLOOD T-CELLS ASSOCIATED WITH A 10P12-13 INTERSTITIAL DELETION

We report oil a 8-year-old patient affected by a selective T-cell defe ct associated with mental retardation and dysmorphic signs. At birth t hymic aplasia and hypoparathyroidism were noted, suggesting a DiGeorge -like anomaly. The immunological evaluation during the 8 years follow- up revealed a progressive decrease of CD3(+)CD4(+) lymphocytes, which paralleled decrease of blood T cells. Chromosome analysis using GTL ba nding revealed an interstitial deletion of the short arm of chromosome 10. We next investigated whether the expression of IL-2R alpha chain and Nil-2-a genes, which are located on the short arm of chromosome 10 , was affected by the deletion. Transcription of these two genes was n ormal, thus suggesting that the two regions were preserved. In situ hy bridization studies with the painting libraries #G3A7 and #G9 confirme d that the two regions were preserved and allowed us to define the bre akpoint as 10p12-10p13. Due to the similarities between DiGeorge and 1 0p syndromes, we suggest that the 10p13-10p12 region contains a gene(s ) potentially related to gene products of the 22q11 region, frequently altered in patients with DiGeorge. (C) 1996 Academic Press, Inc.