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Paternal transmission of fragile X syndrome
Author(s) -
Zeesman Susan,
Zwaigenbaum Lonnie,
Whelan Donald T.,
Hagerman Randi J.,
Tassone Flora,
Taylor Sherryl A.M.
Publication year - 2004
Publication title -
american journal of medical genetics part a
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.064
H-Index - 112
eISSN - 1552-4833
pISSN - 1552-4825
DOI - 10.1002/ajmg.a.30191
Subject(s) - allele , fragile x syndrome , genetics , daughter , mutation , biology , sperm , fmr1 , peripheral blood , gene , immunology , evolutionary biology
We present a family in which a fragile X mosaic male, who carries both premutation and full mutation alleles in his peripheral blood leukocytes, has a daughter with both premutation and partially methylated full mutation alleles and a significant developmental disability. To our knowledge, this is the first report of such an occurrence and it challenges current thinking about the expansion and transmission of unstable FMR1 alleles from men to their daughters. It is currently accepted that neither males with premutations nor full mutations are at risk for having daughters with full mutations and fragile X syndrome. The sperm cells of full mutation males are thought to carry only premutation alleles. These alleles, when transmitted through a male, regardless of his cognitive status, are thought to be unable to expand to full mutations in the next generation. In effect, the expansion from premutation to full mutation has only been observed through female meioses. The sperm cells in the father in this family have been shown to contain only alleles in the premutation range. Since his daughter has both premutation and full mutation alleles the expansion to full mutation in this case must have occurred postzygotically. © 2004 Wiley‐Liss, Inc.