FAMILIAL RING(19) CHROMOSOME MOSAICISM - CASE-REPORT AND REVIEW

Ring (19) chromosomal mosaicism has been identified in a 14-month-old girl referred for cytogenetic evaluation due to microcephaly and devel opmental delay with autistic-like mannerisms. An analysis of her perip heral blood lymphocytes showed a 46,XX,r(19) cell line in 119/121 of c ells examined. Of the two remaining cells, one had a normal female chr omosome complement and the other showed loss of one of the chromosome 19 homologs, Further analysis by fluorescence in situ hybridization us ing an all human telomere probe showed the presence of a single hybrid ization signal on the r(19) chromosome. Subsequent cytogenetic charact erization of cells derived from the patient's phenotypically normal mo ther also demonstrated the presence of a ring 19 chromosome in 4/100 c ells, The remaining cells had a normal female chromosome complement. T hese findings represent the first reported case of familial ring 19 mo saicism, The cytogenetic and clinical findings in these two individual s are discussed in relation to six previously reported eases of de nov o ring chromosome 19 mosaicism. (C) 1996 Wiley-Liss, Inc.