Double autosomal/gonosomal mosaic aneuploidy: study of nondisjunction in two cases with trisomy of chromosome 8.
We report cytogenetic and molecular investigations performed in two cases of mosaic trisomy 8 combined with mosaic sex chromosome aneuploidy. In a 35-year-old female, presenting with short stature, gonadal dysgenesis, and a multiple congenital anomalies/mental retardation syndrome typical of trisomy 8, chromosome analysis from peripheral lymphocytes showed the presence of three cell lines, whose karyotypes were 45,X (59.2%), 46,X,+8 (1.2%), and 47,XX,+8 (39.6%), respectively. The same cell lines were found in a skin fibroblast culture, though in different proportions. The second patient, a 9-month-old male with multiple skeletal abnormalities, showed a 47,XY,+8 and a 47,XXY cell line in both peripheral lymphocytes (61.7% and 38.3%, respectively) and skin fibroblasts (92.8% and 7.2%, respectively). To determine the events underlying the origin of these complex karyotypes we performed Southern blot and polymerase chain reaction (PCR) analysis using polymorphic DNA markers from the X chromosome and from chromosome 8. Both supernumerary chromosomes 8, and, in case 2, the two X chromosomes, appeared to be identical, lacking detectable recombination events. We conclude that, in both cases, the most likely mechanism underlying the origin of the mosaic cell lines was formation of a normal zygote, followed by mitotic errors during early divisions.
DeBrasi
D
D
Servizio Speciale di Citogenetica, Facoltà di Medicina e Chirurgia, Università Federico II, Napoli, Italy.
Genardi
M
M
D'Agostino
A
A
Calvieri
F
F
Tozzi
C
C
Varrone
S
S
Neri
G
G
D000015:Abnormalities, Multiple / Q000235:genetics; D000328:Adult; D000782:Aneuploidy; D001842:Bone and Bones / Q000002:abnormalities; D002898:Chromosomes, Human, Pair 8; D005260:Female; D006059:Gonadal Dysgenesis / Q000235:genetics; D006801:Humans; D007223:Infant; D008607:Intellectual Disability / Q000235:genetics; D008297:Male; D009030:Mosaicism; D010375:Pedigree; D016133:Polymerase Chain Reaction; D012729:Sex Chromosome Aberrations / Q000235:genetics*; D014314:Trisomy / Q000235:genetics*; D014960:X Chromosome / Q000235:genetics*; D014998:Y Chromosome / Q000235:genetics*