Screening for fragile X syndrome: results from a school for mentally retarded children

Abstract

Fragile X screening among mentally retarded children attending a special school should be highly encouraged to reveal the cause of mental retardation and to detect yet unrecognized fragile X individuals. The frequency of fragile X syndrome in a such population in Croatia was found to correlate with similar results from previous studies. However, since at the time of diagnosis all affected families had a second or even a third child born, earlier diagnosis should be considered to provide greater benefit to fragile X families.

Identification of Expanded Alleles of the FMR1 Gene in the CHildhood Autism Risks from Genes and Environment (CHARGE) Study

“…Several studies have also been carried out in different populations of subjects including ID, AUT, or those with special educational needs, to both assess the prevalence of FXS among these populations and to identify subjects with FXS, which is very important for families. In the above studies, using both cytogenetic and molecular approaches, the full mutation rate varies between 0.5 and 16 % and the premutation rate varies between 0 and 0.8 % (Biancalana et al 2004; Blomquist et al 1985; Brown et al 1986; de Vries et al 1998; de Vries et al 1997; Hecimovic et al 2002; Major et al 2003; Mazzocco et al 1997; Mila et al 1997; Pandey et al 2002; Patsalis et al 1999; Pouya et al 2009; Reddy 2005; Schaefer and Lutz 2006; Sharma et al 2001; Syrrou et al 1998; Watson et al 1984; Yuhas et al 2009). A multicenter study conducted in Sweden (Blomquist et al 1985) found FXS in 16 % of boys with infantile autism, and a multicenter survey among individuals with autism found 13 % were positive for FXS (Brown et al 1986).…”

Germline PHOX2B Mutation in Hereditary Neuroblastoma

“…found a 2.2% prevalence of SLC6A8 mutations in families with proven or possible XLMR (the latter are families with at least two males affected by MR and compatible with X-linked inheritance). On the other hand, the FMR1 expansion mutation associated with fragile-X syndrome is found in ∼2%-3% of males with MR who were not selected for family history (these figures are based on cohorts with little clinical preselection apart from the exclusion of clearly chromosomal or syndromic forms of MR) (see de Vries et al 1997;Hecimovic et al 2002;Pandey et al 2002;Grønskov et al 2004;Biancalana et al, in press). In fact, when selection is based on possible X-linked inheritance, the proportion of individuals with fragile-X syndrome is much higher.…”

Comparative Frequency of Fragile-X (FMR1) and Creatine Transporter (SLC6A8) Mutations in X-Linked Mental Retardation

“…Rosenberg et al (2004) found a 2.2% prevalence of SLC6A8 mutations in families with proven or possible XLMR (the latter are families with at least two males affected by MR and compatible with X-linked inheritance). On the other hand, the FMR1 expansion mutation associated with fragile-X syndrome is found in ∼2%-3% of males with MR who were not selected for family history (these figures are based on cohorts with little clinical preselection apart from the exclusion of clearly chromosomal or syndromic forms of MR) (see de Vries et al 1997;Hecimovic et al 2002;Pandey et al 2002;Grønskov et al 2004;Biancalana et al, in press). In fact, when selection is based on possible X-linked inheritance, the proportion of individuals with fragile-X syndrome is much higher.…”