Apparent monosomy 21 owing to a ring 21 chromosome: parental origin revealed by DNA analysis.
A three and a half year old mildly retarded boy is presented. Karyotyping showed monosomy 21 (45,XY,-21) in all 50 metaphase spreads examined from two lymphocyte cultures, and in 20% of cells examined from cultured fibroblasts; the remaining 80% of cells showed a ring 21 chromosome (46,XY,r(21)(p1q22]. Molecular studies using chromosome 21 specific DNA probes confirmed the monosomy in blood and showed that the ring 21 chromosome was paternal in origin. Parental karyotypes were normal.
Dalgleish
R
R
Department of Genetics, University of Leicester.
Duckett
D P
DP
Woodhouse
M
M
Shannon
R S
RS
Young
I D
ID
D002675:Child, Preschool; D002869:Chromosome Aberrations / Q000235:genetics*; D025063:Chromosome Disorders; D002891:Chromosomes, Human, Pair 21; D015342:DNA Probes; D005147:Facial Bones / Q000002:abnormalities; D006801:Humans; D007621:Karyotyping; D008297:Male; D010641:Phenotype; D012303:Ring Chromosomes
D015342:DNA Probes