A gene for FG syndrome maps in the Xq12-q21.31 region

Sylvain Briault, Ruth Hill, Antony Shrimpton, Danping Zhu, Marianne Till, Nathalie Ronce, Patricia Margaritte-Jeannin, Michael Baraitser, Helen Middleton-Price, Sue Malcolm, Elizabeth Thompson, Joe Hoo, Golder Wilson, Corrado Romano, Agnès Guichet, Marcus Pembrey, Michel Fontes, Annemarie Poustka, Claude Moraine

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FG syndrome is an X-linked recessive condition in which mental retardation is associated with congenital hypotonia, macrocephaly, characteristic face, and constipation. This syndrome was mapped by Zhu et al. [Cytogenet Cell Genet 1991;58:2091A] to Xq21.31-q22 by linkage analysis with a max lod score of 1.2 for the DXYS1X, DXS178, DXS101, and DXS94 loci and crossovers at DXS16 (Xp22.31) and DXS287 (Xq22.3). However, this mapping was only provisional and needed to be refined. In this paper, we report the results of a new linkage analysis performed on 10 families including that studied by Zhu et al. [1991]. Two-point analysis demonstrated linkage with DXS441 (Zmax = 3.39 at θ = 0.12) at Xq13. In addition, separate analysis of the lod scores obtained for the Xq13 markers suggested linkage exclusion for three families. Genetic heterogeneity was confirmed by analysis of the linkage results with the HOMOG program, (max logL = 4.07, θ = 0, α= 0.65). Localization of one FG gene between DXS135 and DXS1066 was suggested by analysis of crossovers found in those three families which were assumed to be linked to Xq13 with a probability of 0.95 or more. This region could be reduced to the DXS135-DXS72 interval after combining our data with those from deletions previously described in males in the Xq13-q21 region.

Original languageEnglish
Pages (from-to)87-90
Number of pages4
JournalAmerican Journal of Medical Genetics
Issue number1
Publication statusPublished - Nov 28 1997


  • FG syndrome
  • Genetic heterogeneity
  • Linkage
  • X chromosome

ASJC Scopus subject areas

  • Genetics(clinical)


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