Mosaic trisomy of a small r(1) with an abnormal phenotype

• Published in: American journal of medical genetics 2001-09, Vol.103 (1), p.32-35
• Main Authors: Dawson, A.J., Konkin, D., Riordan, D., Chudley, A.E.
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Child; Chromosome aberrations; Chromosome Banding; Chromosomes, Human, Pair 1 - genetics; clinical phenotype/karyotype correlation; Humans; In Situ Hybridization, Fluorescence; Karyotyping; Male; Medical genetics; Medical sciences; mosaic trisomy r; Mosaicism; Phenotype; Ring Chromosomes; supernumerary marker chromosome; Trisomy
• ISSN: 0148-7299; 1096-8628
• DOI: 10.1002/ajmg.1494

Cytogenetic studies of a mildly dysmorphic 10‐year‐old male with mild developmental delay and learning difficulties revealed mosaicism for a supernumerary ring chromosome in approximately half of the cells. The karyotype of this patient was established as 47,XY,+r[15]/46,XY[15].ish r(1)(D1Z7+,wcp1−). Although the presence of euchromatic material was shown by C banding, the lack of hybridization with the whole chromosome paint 1 (wcp1) probe suggests that few unique sequences are contained in the ring and that these sequences likely explain the child's dysmorphic features and developmental delay. A review of the literature, including the present case, suggests that the significance of euchromatin in supernumerary r(1) as determined by both C banding and fluorescence in situ hybridization (FISH) with chromosome 1 painting probes can be used as a prognostic indicator for potential severity of the clinical phenotype. © 2001 Wiley‐Liss, Inc.