Different clinical features in monozygotic twins: a case of 7q--syndrome.
We present male monozygotic twins who showed quite different clinical features. Blood chromosome analysis revealed 46,XY/46,XY,del(7) (q32-->qter) mosaicism in both twins. However, cultured skin fibroblasts from the twins showed different karyotypes. Twin 1, with a normal phenotype, had normal chromosomes and was 46,XY. Twin 2, on the other hand, had the characteristic manifestations of 7q- syndrome and chromosomes of 46,XY,del(7) (q32-->qter). DNA fingerprint analysis of their peripheral blood samples revealed the same pattern. However, DNA fingerprint patterns of cultured skin fibroblasts and buccal mucosal cells were different when a 7q terminal marker, probe g3, was used. These identical twins with discordant phenotypes can be explained by the occurrence of twinning and simultaneous erroneous mitosis. In addition, there might be a vascular communication which probably resulted in blood exchange and chromosomal mosaicism of the lymphocytes of the monozygotic twins.
Tsukamoto
H
H
Department of Pediatrics, Osaka University School of Medicine, Japan.
Inui
K
K
Taniike
M
M
Kamiyama
K
K
Hori
M
M
Sumi
K
K
Okada
S
S
D000015:Abnormalities, Multiple / Q000235:genetics*; D002675:Child, Preschool; D002871:Chromosome Banding; D002872:Chromosome Deletion; D002897:Chromosomes, Human, Pair 7; D016172:DNA Fingerprinting; D002658:Developmental Disabilities / Q000235:genetics*; D005147:Facial Bones / Q000002:abnormalities; D006801:Humans; D008297:Male; D009030:Mosaicism / Q000235:genetics; D010641:Phenotype; D012886:Skull / Q000002:abnormalities; D013577:Syndrome; D014430:Twins, Monozygotic / Q000235:genetics*