ABSTRACT
We report a case of familial small supernumerary marker chromosome (sSMC) in a child with translocation Down syndrome (DS)and mother.The GTG-banded chromosomal analysis of DS child revealed 47,XY,+21,+mar and mother karyotype was 47,XX,+mar.The GTG-banded sSMC had a similar morphology of small acrocentric chromosomes .Fluorescence in situ hybridization (FISH)evaluation of sSMC using centromere probes(13/21,14/22,22)confirmed sSMC as derivative chromosome 14.The sSMC was not specifically stained with whole chromosome paint and arm-specific probes for chromosome 14;thus it has been described as der(14)(:p11-q11:).The phenotypic changes were not evident, may be due to trisomy condition in the child or the sSMC contain repetitive sequences.
Subject(s)
Adolescent , Chromosome Banding , Chromosomes, Human, Pair 14/genetics , Down Syndrome/genetics , Female , Humans , In Situ Hybridization, Fluorescence , Infant , Male , Translocation, Genetic/genetics , Trisomy/geneticsABSTRACT
Four months old, female child, referred for cytogenetic analysis, showed mosaiciam for the marker chromosome. Her karyotype: 47,XX,+21/48,XX+21 mar (pat). The karyotype of her mother & her sib were normal. Her father showed, similar to the proband, mosaicism for the marker ie 46,XY/47,XY, + mar. AgNOR technique determined the marker as fused short arms of the acrocentric chromosome. Four months old, female child, referred for cytogenetic analysis, showed mosaiciam for the marker chromosome. Her karyotype: 47,XX,+21/48,XX+21 mar (pat). The karyotype of her mother & her sib were normal. Her father showed, similar to the proband, mosaicism for the marker ie 46,XY/47,XY, + mar. AgNOR technique determined the marker as fused short arms of the acrocentric chromosome.