Robertsonian Translocation in a Down Syndrome: A Case Report
Year: 2015
Type: article
Study design: Case Report
Abstract: Background: Down syndrome also known as Trisomy 21 is a genetic disorder associated with presence of whole or part of third copy of chromosome 21. It is typically associated with characteristic facial features with varying degree of intellectual disability. The frequency of Down syndrome in Indian population is roughly estimated at 1 in every 920 live births. Almost 90% of Down Syndrome are due to pure trisomy 21, 6-7% are of mosaic types (with both normal and trisomy cells) and 3-4% are due to translocation of chromosome 21 to other acrocentric chromosomes. Casereport:We report a 1year old girl born with congenital cardiac anomalies and typical facial features suggestive of Down syndrome like small chin, upward slanting eyes and flat nasal bridge. 5ml of venous blood was cultured for leucocytes and subsequently karyotyped using standard protocol of Trypsin Giemsa banding. Cytogenetic analysis of peripheral blood revealed Down Syndrome with unbalanced Robertsonian translocation between chromosomes 14 and 21 with 3 copies of long arm of chromosome 21. The karyotype revealed 46,XX,rob(14;21)(q10;q10),+21. The carrier status for balanced translocations for both parents were identified by peripheral blood karyotype and was found to be have normal karyotype. Conclusions: Translocation in Down syndrome is usually of Robertsonian type with fusion of chromosome 21 to D or G group chromosome. Most frequent forms are t(14;21) and t(21;21). The occurrence of translocations is either sporadic or secondary if one of the parents is carrier of a balanced translocation. Most translocation Down Syndrome cases are born to young mothers less than 25 years of age when compared with pure trisomy 21 cases. The carrier status of both parents must be established to determine the probability of recurrence of Down syndrome in the next child. Thus parental karyotype, parental ages and family history together help to provide estimation of risk for the next conception.
Authors: Debasis Bandopadhyay, Bhatnagar Rajan
Language: English
Field: Medicine
Domain: Health Sciences
Open Access status: diamond
OpenAlex ID: W152118556