Emine YAŞAR, Serdar KARATOPRAK, İbrahim TEKEDERELİ, Serap SAVACI, Cemal EKİCİ

Rare Translocations in Two Newborns with Down Syndrome

Trizomi 21, insanlarda en sık görülen kromozomal anöploidi olup sıklığı yaklaşık olarak 700 canlı doğumda 1'dir (1:700). Olguların %95'i klasik tip Down sendromu olup, fazla olan 21. kromozom serbesttir. Kalan vakaların yaklaşık yarısı 14/21 translokasyonu ile meydana gelirken, yarısını ise 21/21, 15/21 gibi diğer Robertsonian tipi translokasyonlar ve mozaik trizomiler oluşturur. Klasik ya da translokasyon tipi Down sendromu arasında fenotipik fark olmamasına rağmen, translokasyon tipi Down sendromunda ebeveynlerin taşıyıcı olma ihtimali gözönüne alınarak, anne-baba kromozom analizi yapılması gereklidir. Bu çalışmada Down sendromu bulguları nedeni ile başvuran iki yenidoğanın tanı, komorbid durumlar ve genetik danışmanlık süreci literatür bilgileri ışığında değerlendirilerek sunulmuştur.

Down Sendromlu İki Yenidoğanda Nadir Translokasyonlar

Trisomy 21 is the most common chromosomal aneuploidy in humans with a frequency of about 1:700 live births. Free trisomy 21 constitutes about 95% of all cases, also known as standard Down syndrome. Nonclassic trisomies constitutes 5% and within this group almost half have 14/21 while the remainder carry 21/21, 15/21, and other Robertsonian translocations and mosaic trisomies. Although there are no phenotypic differences between standard and translocation trisomy 21, the latter could be the result of the possibility that one of the parents is a carrier for translocation. Therefore, parents' karyotypes should be evaluated in such cases. In this study, we report the process of diagnosis, comorbid conditions, and genetic counseling in two newborn patients with Down syndrome in the light of current literature.

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