First patient with trisomy 21 accompanied by an additional der(4)(:p11 --> q11:) plus partial uniparental disomy 4p15-16.
We report on a rare additional numerical chromosomal aberration in a child with Down syndrome due to free trisomy 21. The karyotype showed 48,XY,+21,+mar after GTG banding, with the marker present in 80% of cells. The supernumerary marker chromosome (SMC) was as small as approximately one-third of 18p, and with the recently developed centromere-specific multi-color fluorescence in situ hybridization (cenM-FISH) technique, it was shown that the SMC was a derivative chromosome 4. The SMC was not specifically stained by arm-specific probes for chromosome 4; thus, it has been described as der(4)(:p11 --> q11:). Microsatellite analysis resulted in a partial maternal uniparental isodisomy (UPD) for chromosome 4p15-16 and a maternal origin for two chromosomes 21. Until now only two similar cases have been described in the literature, but without clarifying the origin of the SMC and without looking for an additional UPD. This is the only reported case of a UPD 4p in a liveborn child.
Starke
Heike
H
Institute of Human Genetics and Anthropology, Jena, Germany.
Mitulla
Beate
B
Nietzel
Angela
A
Heller
Anita
A
Beensen
Volkmar
V
Grosswendt
Gisela
G
Claussen
Uwe
U
von Eggeling
Ferdinand
F
Liehr
Thomas
T
D002869:Chromosome Aberrations; D002871:Chromosome Banding; D002891:Chromosomes, Human, Pair 21 / Q000235:genetics*; D002894:Chromosomes, Human, Pair 4 / Q000235:genetics*; D004314:Down Syndrome / Q000235:genetics / Q000473:pathology; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D007223:Infant; D007621:Karyotyping; D008297:Male; D014314:Trisomy; D024182:Uniparental Disomy