CYTOGENETIC AND MOLECULAR STUDIES OF SIBLINGS WITH ATAXIA-TELANGIECTASIA FOLLOWED FOR 7 YEARS

We present cytogenetic, immunologic, and molecular data obtained over 7 years from a family with ataxia telangiectasia (AT) including 2 affe cted children and their unaffected sibling, and their obligate heteroz ygous parents. In a period of 3 years, the T lymphocytes front both AT patients showed clonal rearrangements of chromosomes 7 and 14 at spec ific bands (7p13, 7q35, 14q12, and 14q32), where loci for the Ig and T CR genes are located. A molecular study was carried out on peripheral blood and bone marrow samples from both patients using Southern blot a nd PCR for Ig and TCR genes. A monoclonal population for TCR gamma was observed in one of the two affected children, but only in peripheral blood. (C) Elsevier Science Inc., 1997.