engleski

Identification of supernumerary marker chromosome derived from chromosome 19p

Supernumerary marker chromosome represent a heterogeneous group of extra structually abnormal chromosomes wich have different expression in phenotype of affected person. The proband, a 9-month-old male, was referred to laboratory for cytogenetic study due to a history of mental retardation, developmental delay and dysmorphic features. Routine chromosomal analysis of the proband was performed on GTG-banded metaphases from cultures of PHA-stimulated peripheral blood lymphocytes. Cytogenetic analysis revealed mosaicism for marker chromosome in 52% of the analysed cells. The probands parents had normal karyotype. Fluorescence in situ hybridization with centromere cross-hybridizing probes D1/5/19Z showed strong signal on marker chromosome. The whole chromosome paint 19 showed the signal from the marker confirming its chromosome 19 origins. Subsequent FISH with pool YACs19p(839B1, 872G3, 728C8) and poolYACs 19q (767C4, 761C1, 786G6) indicated the marker chromosome to be derived from chromsome 19p arm. This is the first reported case of de novo extra structually abnormal chromosome derived from short arm of chromosome 19. Abnormalities of the short arm chromosome 19 are uncommon so this case may achieve a better delineation of karyotype-phenotype corelations.

marker chromosome; chromosome 19p

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