Fragile X syndrome (FXS) is caused by a full mutation expansion (>200 CGG repeats) in the FMR1 gene that results in a deficiency of the fragile X mental retardation protein. Although most individuals with the premutation (55-200 CGG repeats) are considered unaffected by FXS, recent case studies have documented children with the premutation who have cognitive deficits, behavioral problems, and/or autism spectrum disorders. The objective of this study was to compare the prevalence of autism spectrum disorders (ASD) and attention-deficit hyperactivity disorder (ADHD) symptoms in boys with the premutation who presented as probands, in brothers with the premutation who did not present as probands, and in normal brothers of premutation and/or full mutation carriers. Participants included 43 male children: 14 probands who presented to clinic, 13 nonprobands who were identified through cascade testing (routine genetic testing of family members after identification of a proband) and confirmed to have the premutation, and a control group of 16 male siblings of individuals with the fragile X premutation or full mutation who were negative for the FMR1 mutation. Participants came from 1 of 2 collaborative sites: University of California, Davis and La Trobe University in Australia. Parents completed the Conners' Global Index-Parent Version for assessing symptoms of ADHD and the Social Communication Questionnaire (SCQ) for identifying symptoms of ASD. Children who were in the ASD range on the SCQ (n = 13) underwent further evaluation with either the Autism Diagnostic Observation Schedule-Generic (n = 10) or the Autism Diagnostic Interview-Revised (n = 3). A final diagnosis of ASD included clinical assessment utilizing DSM-IV-TR criteria in addition to the standardized assessments. There was a higher rate of ASD in boys with the premutation presenting as probands (p < 0.001) or nonprobands (p < .04) compared with sibling controls without the premutation. In addition, probands had a significant increase in ADHD symptoms compared with controls (p < .0001). Of the probands, 93% had symptoms of ADHD and 79% had ASD. In the nonproband premutation group, 38% had symptoms of ADHD and 8% had ASD. Thirteen percent of sibling controls had symptoms of ADHD and none had ASD. IQ scores were similar in all 3 groups (p = .13), but the use of psychotropic medications was significantly higher in probands with the premutation compared with that in controls (p < .0001). Developmental problems have been observed in premutation carriers, particularly those who present clinically with behavioral difficulties. Although this study is based on a small sample size, it suggests that premutation carriers, even those who do not present clinically, may be at increased risk for an ASD and/or symptoms of ADHD. If the premutation is identified through cascade testing, then further assessment should be carried out for symptoms of ADHD, social deficits, or learning disabilities.

No abstract

Purpose: To conduct a systematic review of literature regarding population-based screening for fragile X syndrome in newborns and women of reproductive age, either before or during pregnancy. Methods: Seven electronic databases were searched for English language studies published between January 1991 and November 2009. Data extraction was performed for all included studies. Results were synthesized using a narrative approach. Results: One article that examined offering newborn screening for fragile X syndrome and 10 that examined the offer of fragile X syndrome screening to women of reproductive age were identified. Two of these articles also addressed psychosocial aspects of population screening for fragile X syndrome such as attitudes to screening and experiences of screening, and a further nine addressed these issues alone. Studies exploring psychosocial issues demonstrated challenges for counseling arising from a lack of awareness or personal experience with fragile X syndrome in the general population. Conclusions: Targeted counseling and educational strategies will be essential to support women from the general population. It is crucial that future studies offering screening for fragile X syndrome explore a range of psychosocial aspects in addition to looking at uptake of testing and mutation frequency. Genet Med 2010:12(7):396 -410.Key Words: attitudes, carrier screening, fragile X syndrome, newborn screening, psychosocial P opulation-based screening programs for a number of genetic conditions have been established in newborn, prenatal, and preconception settings. Specific criteria, such as those developed by the World Health Organization, 1,2 are available to provide guidance on which conditions are suitable for screening. 3 Fragile X syndrome (FXS) is an X-linked genetic condition for which possible inclusion in population-based screening programs has been discussed and debated for many years. 4 -7 FXS is the most common known cause of inherited intellectual and developmental disability. It has a serious adverse impact on individuals and their families that is equivalent to that of other disabilities such as Down syndrome and autism. Most FXS cases are caused by the silencing of the FMR1 gene, which is located on the X chromosome. In these cases, the FMR1 gene is switched off as a result of an increase in the number of hypermethylated trinucleotide (CGG) repeats in the 5Ј untranslated region of the gene. Current definitions describe the normal range of CGG repeats as 6 -44, the "gray zone" range as 45-54 repeats, and the premutation range as 55-199 repeats. 8 Those affected by FXS have Ͼ200 repeats (full mutation). The length of the CGG repeat is unstable over a certain size, such that a premutation can expand to a full mutation when passed onto offspring through female, but not male, premutation carriers. 9 -11 Similarly, a gray zone allele can increase to a premutation allele when transmitted to offspring, such that a grandchild could be affected with FXS.The full mutation is associated with intell...

Population carrier screening for fragile X syndrome can provide women with information about their risk of having a child with fragile X syndrome and their risk of fragile Xassociated primary ovarian insufficiency and fragile X-associated tremor ataxia syndrome. Few studies have explored women's decisions when offered carrier screening for fragile X syndrome. Interviews were conducted with 31 women who participated in a pilot study offering carrier screening to nonpregnant women. A qualitative approach was used to gain an in-depth understanding of women's experiences and examine their decision-making processes, including women who were tested and those who decided not to be tested. The decisionmaking process occurred in two phases. In the first phase, the participant's reproductive stage of life and experience with illness and disability were major factors influencing whether she would consider screening. In the second phase of decision -making, participants' perceptions of the value of knowing their carrier status was the most notable factor for influencing whether a woman actually had the carrier test. Some women appreciated having time for deliberation and those who were tested did not express regret about their decision. Our findings support offering carrier screening for fragile X syndrome to non-pregnant women and suggest that women from the general population will have specific informational and counseling needs when offered carrier testing. This study highlights the unique challenges encountered by women from the general population when making a decision about testing for fragile X syndrome carrier status and illustrates the importance of understanding how women make decisions.

No abstract