Yarbrough K M, Howard-Peebles P N
Clin Genet. 1976 Feb;9(2):125-30. doi: 10.1111/j.1399-0004.1976.tb01557.x.
A seven-generation pedigree of apparent X-linked, nonspecific mental retardation is reported. There are 19 known affected males who appear to have received the gene through normal mothers. Retardation, lack of fine motor coordination, hyperactivity and a speech defect are the characteristics of affected individuals studied.