A de novo reciprocal t(2;18) translocation with regular trisomy 21.
A 4-year-old girl with Down syndrome exhibited an autosomal translocation t(2;18) in addition to trisomy 21. An evaluation of GTG-banded metaphases revealed the karyotype 47,XX,t(2;18),21 that was confirmed by using fluorescent in situ hybridization (FISH) probes. This case represents a very rare coincidence of an autosomal aneuploidy and a structural rearrangement. Her parents showed a normal chromosome complement. The translocation must have been an apparently "balanced" one as the proband presented with typical features of Down syndrome alone. The mechanism of origin of this rearrangement along with a nondisjunctional error and its significance are discussed.
Cyrus
Cyril
C
Department of Genetics, University of Madras, Taramani Campus, Chennai, India.
Kaur
Harpreet
H
Koshy
Teena
T
Thankanadar
Jegatheesan
J
Nallathambi
Chandra
C
D002675:Child, Preschool; D002887:Chromosomes, Human, Pair 18; D002889:Chromosomes, Human, Pair 2; D002891:Chromosomes, Human, Pair 21; D004314:Down Syndrome / Q000235:genetics*; D005260:Female; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D007621:Karyotyping; D014178:Translocation, Genetic