SNP Microarray Characterization and Genotype-Phenotype Analysis in a Patient with a Ring Chromosome 22

Ring chromosome 22 is a rare cytogenetic anomaly. The aim of this study was to present a case carrying ring chromosome 22 in a 9-year-old Chinese girl with long face, thick eyebrows, large and low-set ears, mental retardation, severe speech delay, autistic disorders and talipes equinovarus (TEV). A chromosome analysis of the proband revealed a de novo 46,XX,r(22)(p13;q13) karyotype and the deleted region was confirmed by means of SNP microarray analysis showing deletion range from 22q13.31 to 22q13.33 (3.8Mb). The present report describes the case of a patient with a ring chromosome 22 abnormality completely characterized by SNP microarray which provided additional information for genotype-phenotype studies. Address for correspondence: Dr. Chenming Xu Department of Reproductive Genetics, Women’s Hospital, Medical School, Zhejiang University, No 1 Xueshi Road, Hangzhou, Zhejiang 310006, China Telephone: +86-15858223895. E-mail: [email protected] INTRODUCTION Ring chromosome 22, firstly described by Weleber et al. (1968), is a rare cytogenetic anomaly. Its most consistent findings are overall developmental delay with severe language impairment, growth and mental retardation. It’s frequently associated hypotonia and craniofacial anomalies such as microcephaly, normally placed but large and dysplastic ears, long face, thick eyebrows, epicanthus, long eyelashes with full eyebrows and so on. Here the researchers report a case of de novo ring chromosome 22 in a 9-year-old girl presented with mental retardation, severe speech delay, minor dysmorphic features, hypotonia, autistic disorders and talipes equinovarus (TEV). The abnormal karyotype was identified by conventional cytogenetics, while chromosome rearrangements were characterized by SNP microarray. The researchers tried to establish the size of the associated deletion in ring chromosome 22 by means of SNP microarray and to obtain more precise details for genotype-phenotype correlations.