Ieshima A, Ogasawara N, Yamamoto Y, Kuroki Y
Hum Genet. 1980;55(1):65-9. doi: 10.1007/BF00329128.
A case of r(21) with stigmata of atypical Down syndrome is presented. Karyotype of the proposita was determined as 45,XX,-21/46,XX,-21,+r(21)/47,XX,-21,+r(21),+(21). Most ring chromosomes showed double-sized ring chromosomes, which were trisomic for 21p11-21q22.3 and monosomic for 21q22.3-qter. SOD-1 activity revealed only slight elevation. The mechanism of ring formation is discussed.
本文报告一例具有非典型唐氏综合征特征的r(21)病例。先证者的核型确定为45,XX,-21/46,XX,-21,+r(21)/47,XX,-21,+r(21),+(21)。大多数环状染色体显示为双倍大小的环状染色体，这些染色体在21p11-21q22.3区域为三体，在21q22.3-qter区域为单体。超氧化物歧化酶-1（SOD-1）活性仅略有升高。文中讨论了环状染色体形成的机制。
