A 4.6 kb genomic duplication on 20p12.2-12.3 is associated with brachydactyly type A2 in a Chinese family

作者:Su, Peiqiang; Ding, Hongke; Huang, Dongsheng; Zhou, Yan; Huang, Weijun; Zhong, Liangying; Vyse, Tim J.; Wang, Yiming*
来源:Journal of Medical Genetics, 2011, 48(5): 312-316.
DOI:10.1136/jmg.2010.084814

摘要

Background Brachydactyly type A2 (BDA2) is an autosomal dominant disorder. It was recently reported that a 5.9 kb duplication and a 5.5 kb duplication in the region 20p12.2-12.3 are associated with BDA2 in two European families. @@@ Objective To characterise a 6-generation Chinese family with 16 members affected by BDA2 and map the gene to 20p12.2-12.3. @@@ Methods and results A 4.6 kb duplication downstream of the bone morphogenetic protein 2 (BMP2) was identified in the family. The duplication co-segregated with the phenotype and was absent in unaffected family members and control subjects. Coding and splice-site mutations of all annotated genes in the critical region were also excluded. The duplication partially overlaps with the reported duplications but has a different breakpoint. The most conserved 2.1 kb fragment in the duplication was cloned into the pGL3-promoter vector downstream of the firefly luciferase reporter gene in the 5' to 3' orientation and transfected into osteosarcoma U-2OS and Hela cells. A reduced luciferase activity was observed. @@@ Conclusion The smallest duplication is described, which partially overlaps the reported duplications but has a different breakpoint, and its association with BDA2 in a Chinese family is confirmed. The results also provide evidence for cis-regulatory sequences in the duplication 3' of BMP2.