A case with mosaic ring chromosome 18

Ring kromozom oluşumunun klasik modu, etkilenen kromozomun her iki kolunda kırık oluşması, kırılma noktalarının füzyonu ve distal fragmanların kaybıdır. 18. kromozomun ring kromozomu, ring kromozomlar içinde nadirdir ve 18p ve 18qdaki delesyon büyüklüğüne bağlı olarak 18p ve 18q sendromlarının tipik klinik işaretlerine sahip olma oranı değişir. Ring 18 fenotipi, gelişme geriliği, mental retardasyon ve başlıca spesifik olmayan anomalilerle karakterize olup, fasiyal dismorfizm ve malformasyonlar gözlenebilir. Konjenital malformasyon, motor mental retardasyon (MMR), kısa boy, yüksek damak, pektus ekskavatus ön tanılarıyla refere edilen olgumuz genetik açıdan değerlendirilmiştir. Olguya ait periferik kan lenfositlerinden 72 saatlik kültür sonucu elde edilen metafaz plaklarına GTL bantlama ve FISH metodları uygulanmıştır. Yapılan kromozom analizi sonucu olgunun karyotipi 46,XX,r(18)[25]/46,XX[75] olarak belirlenmiş, FISH analizi sonucunda bu karyotip doğrulanmıştır.

Mozaik ring kromozom 18 olan bir olgu

The classical mode of ring chromosome formation is by break forming inboth arms of the affected chromosome, fusion of the breaking points andloss of the distal fragments. Ring chromosome of the chromosome 18 isrelatively common among ring chromosomes and the rate of having typicalclinical sings of 18p and 18q sydromes vary related to the length of thedeletion in 18p and 18q. Ring 18 phenotype is characterised by growthretardation, mental retardation and nonspecific abnormalities, also facialdysmorphism and malformations may be observed. Our case referred withcongenital malformation, motor mental retardation (MMR), short stature,high palate, pectus excavatus was evaluated genetically. GTL banding andFISH methods were performed for the metaphase plaques obtained fromperipheral lymphocytes cultered for 72 hours. The karyotype of the case wasdetected to be 46,XX,r(18)[25]/46,XX[75] and confirmed by FISH analysis.

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