Functional mosaic trisomy of 1q12-->1q21 resulting from X-autosome insertion translocation with random inactivation.
Cytogenetic studies of a 16-year-old female with behaviour and learning problems revealed that one X chromosome had additional material inserted at Xq21. Fluorescence in situ hybridization (FISH) analysis showed that the inserted segment contained heterochromatin and adjacent euchromatin of chromosome 1 origin. The karyotype of this patient was established as: 46,X,der(X)ins(X;?)(q21;?).ish der(X) ins(X;1)(q21;q12q21)(wcp1+). Chromosome replication studies demonstrated a random pattern of X inactivation, suggesting that the inserted material may be too 'small' to skew lyonization. The consequences of this abnormal X chromosome in relation to the clinical phenotype are discussed.
Vust
A
A
Division of Laboratory Medicine and Pathology, Health Sciences Centre, University of Manitoba, Winnipeg, Canada.
Riordan
D
D
Wickstrom
D
D
Chudley
A E
AE
Dawson
A J
AJ
D000293:Adolescent; D002871:Chromosome Banding; D002878:Chromosomes, Human, Pair 1; D004303:Dosage Compensation, Genetic; D005260:Female; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D008607:Intellectual Disability / Q000235:genetics*; D001523:Mental Disorders / Q000235:genetics*; D009030:Mosaicism / Q000235:genetics; D014178:Translocation, Genetic; D014314:Trisomy; D014960:X Chromosome