Giampietro PF, Haas BR, Lipper E, Gutman A, Zellers NJ, LaTrenta GS, Brooks SS, Matalon R, Kaul R, Ding XH, Brown WT. Fragile X syndrome in two siblings with major congenital malformations.
AMERICAN JOURNAL OF MEDICAL GENETICS 1996;
63:396-400. [PMID:
8725793 DOI:
10.1002/(sici)1096-8628(19960517)63:2<396::aid-ajmg14>3.0.co;2-f]
[Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
We report on 2 brothers with both fragile X and VACTERL-H syndrome. The first sibling, age 5, had bilateral cleft lip and palate, ventricular septal defect, and a hypoplastic thumb. The second sibling, age 2 1/2, had a trachesophageal fistula, esophageal atresia, and vertebral abnormality. High-resolution chromosome analysis showed a 46, XY chromosome constitution in both siblings. By PCR and Southern blot analysis, the siblings were found to have large triplet repeat expansions in the fragile X gene (FMR 1) and both had methylation mosaicism. Enzyme kinetic studies of iduronate sulfatase demonstrated a two-fold increase in activity in the first sib as compared to the second. Possible mechanisms through which the fragile X mutation can cause down-regulation of adjacent loci are discussed.
Collapse