Duplication dup(1)(q32q44) detected by comparative genomic hybridization (CGH): Further delineation of trisomies 1q

Partial trisomy 1q is rare and mostly the result of an abnormal segregation of parental translocation chromosomes and their homologues. Only 31 cases have been described with pure partial trisomy 1q. In the fetus presented, c hromosome analysis after amniocentesis had shown an unbalanced male karyoty pe with an aberrant chromosome 1. A de novo terminal duplication of the lon g arm was suspected but could not be verified by FISH in 1994. Five years a fter fetal death, retrospective identification of the additional material i n 1q could finally be achieved by comparative genomic hybridization (CGH) u sing DNA extracted from formalin-fixed and paraffin-embedded fetal tissues. A direct duplication dir dup (1)(pter --> q44::q32.1 --> qter) was found. Only 6 other individuals with duplication of this segment have been describ ed so far. Comparative delineation of a dup1q phenotype with regard to size and origin of the dup (1q) segment evidenced that large duplications as we ll as proximal and interstitial duplications coincide with more severe visc eral malformations, severe mental retardation and a short life span. Termin al duplications (1q32 --> qter) concur with less severe malformations and l onger periods of survival, but marked mental retardation. With small termin al duplications (1q42 --> qter) dysmorphisms are usually mild and intellect ual performance is mostly in the normal range. Copyright (C) 2001 S.KargerA G, Basel.