DNA testing for fragile X syndrome in schools for learning difficulties.

Slaney, Sarah F.; Wilkie, Andrew O.M.; Hirst, Mark C.; Charlton, R. William; McKinley, MJ; Pointon, Jennifer J.; Christodoulou, Zóe; Huson, Susan M.; Davies, Kay E.

doi:10.1136/adc.72.1.33

Cited by 31 publications

(20 citation statements)

References 21 publications

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“…The confidence limits, available for only four of these studies, vary widely, with a lower boundary of 1 in 1,333 40 to an upper boundary of 1 in 8,922. 41 Three studies summarized in Table 1 did not report point estimates: two 42,43 provided a range and one 44 provided a lower boundary, all of which fall within the point estimates and confidence intervals reported in the other studies ( Table 1).…”

Section: Full Mutation and Males: Caucasian Populations Of Northern Ementioning

confidence: 51%

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FMR1 and the fragile X syndrome: Human genome epidemiology review

Crawford

Acuña

Sherman

2001

Genetics in Medicine

578

391

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The fragile X syndrome, an X-linked dominant disorder with reduced penetrance, is one of the most common forms of inherited mental retardation. The cognitive, behavioral, and physical phenotype varies by sex, with males being more severely affected because of the X-linked inheritance of the mutation. The disorder-causing mutation is the amplification of a CGG repeat in the 5' untranslated region of FMR1 located at Xq27.3. The fragile X CGG repeat has four forms: common (6 -40 repeats), intermediate (41-60 repeats), premutation (61-200 repeats), and full mutation (Ͼ200 -230 repeats). Population-based studies suggest that the prevalence of the full mutation, the disorder-causing form of the repeat, ranges from 1/3,717 to 1/8,918 Caucasian males in the general population.The full mutation is also found in other racial/ethnic populations; however, few population-based studies exist for these populations. No population-based studies exist for the full mutation in a general female population. In contrast, several large, population-based studies exist for the premutation or carrier form of the disorder, with prevalence estimates ranging from 1/246 to 1/468 Caucasian females in the general population. For Caucasian males, the prevalence of the premutation is~1/1,000. Like the full mutation, little information exists for the premutation in other populations. Although no effective cure or treatment exists for the fragile X syndrome, all persons affected with the syndrome are eligible for early intervention services. The relatively high prevalence of the premutation and full mutation genotypes coupled with technological advances in genetic testing make the fragile X syndrome amenable to screening. The timing as well as benefits and harms associated with the different screening strategies are the subject of current research and discussion. Genet Med 2001:3(5):359 -371.

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Section: Full Mutation and Males: Caucasian Populations Of Northern Ementioning

confidence: 51%

“…Millan et al 43 also acknowledged that persons with mild MR might have been missed, so the range could be as high as 1/5,000 -1/6,800. h Slaney et al 44 only provided a lower boundary, not a point estimate.…”

Section: Disease(s)mentioning

confidence: 99%

FMR1 and the fragile X syndrome: Human genome epidemiology review

Crawford

Acuña

Sherman

2001

Genetics in Medicine

578

391

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“…A class III prospective study of 103 males with moderate to severe learning difficulties yielded a 3.9% incidence among males for the FMR1 mutation using molecular techniques. 55 Pooled data (see table 2, bottom) from seven studies involving 785 females with varying degrees of mental retardation found an incidence of the fragile X mutation of 2.5%. [48][49][50][51][52][53][54] In a more recent study of 2,757 individuals with mental retardation, 2.6% had fragile X mutations and one-third of these individuals were female.…”

mentioning

confidence: 99%

Practice parameter: Evaluation of the child with global developmental delay [RETIRED]

et al. 2003

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Abstract-Objective:To make evidence-based recommendations concerning the evaluation of the child with a nonprogressive global developmental delay. Methods: Relevant literature was reviewed, abstracted, and classified. Recommendations were based on a four-tiered scheme of evidence classification. Results: Global developmental delay is common and affects 1% to 3% of children. Given yields of about 1%, routine metabolic screening is not indicated in the initial evaluation of a child with global developmental delay. Because of the higher yield (3.5% to 10%), even in the absence of dysmorphic features or features suggestive of a specific syndrome, routine cytogenetic studies and molecular testing for the fragile X mutation are recommended. The diagnosis of Rett syndrome should be considered in girls with unexplained moderate to severe developmental delay. Additional genetic studies (e.g., subtelomeric chromosomal rearrangements) may also be considered in selected children. Evaluation of serum lead levels should be restricted to those children with identifiable risk factors for excessive lead exposure. Thyroid studies need not be undertaken (unless clinically indicated) if the child underwent newborn screening. An EEG is not recommended as part of the initial evaluation unless there are historical features suggestive of epilepsy or a specific epileptic syndrome. Routine neuroimaging, with MRI preferred to CT, is recommended particularly if abnormalities are found on physical examination. Because of the increased incidence of visual and auditory impairments, children with global developmental delay may undergo appropriate visual and audiometric assessment at the time of diagnosis. Conclusions: A specific etiology can be determined in the majority of children with global developmental delay. Certain routine screening tests are indicated and depending on history and examination findings, additional specific testing may be performed.

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“…It helps identifying carriers of the disease and offers a possibility of its prevention, and regarding the child with the fragile X syndrome it provides an opportunity for a better understanding and proper treatment of these individuals. Moreover, genotype/phenotype studies in fragile X individuals contributed to the evaluation of the high risk phenotype for more selective fragile X detection that would increase the proportion of positive cases and would therefore contribute to cost-effectiveness of such screening [6, 20, 25, 29]. …”

Section: Discussionmentioning

confidence: 99%

“…Fragile X screening programmes have been extensively used to estimate the prevalence of the fragile X syndrome and to identify unrecognised cases [4, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24]. Moreover, genotype/phenotype correlations in fragile X individuals contributed to the evaluation of the high risk phenotype for a more selective fragile X detection [6, 19, 25].…”

Section: Introductionmentioning

confidence: 99%

DNA Analysis of the Fragile X Syndrome in an at Risk Pediatric Population in Croatia: Simple Clinical Preselection Criteria Can Considerably Improve the Cost-Effectiveness of Fragile X Screening Studies

Hečimović

Barišić²,

Pavelić³

1998

Hum Hered

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Advances in understanding the molecular basis of the fragile X syndrome, the most common cause of inherited mental retardation, have elicited new prospects for population-based studies identifying affected individuals and fragile X families, thus contributing in prevention of the disease. In comparison with numerous fragile X screening studies where unselected groups of individuals with mental retardation, developmental delay, learning disability or autistic-like behaviour had been observed, we performed fragile X analysis on clinically preselected indivuduals. The group we studied consisted of 108 children with mental retardation of unknown cause or positive family history who had at least one physical and/or behavioural characteristic often observed among fragile X individuals. A relative high frequency of the fragile X positive cases (13% overall, 17.3% in males) was detected, suggesting that simple preselection criteria can considerably increase the proportion of fragile X-positive cases, and therefore, improve the cost-effectiveness of fragile X testing. Retrospective clinical analysis using a simplified six-item fragile X checklist confirmed that scoring criteria can be used to additionally preselect individuals at risk. Our results also indicate that this syndrome is underdiagnosed in Croatia and that a further effort must be made to detect unrecognised cases.

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DNA testing for fragile X syndrome in schools for learning difficulties.

Abstract: (Arch Dis Child 1995; 72: 33-37)

Cited by 31 publications

References 21 publications

FMR1 and the fragile X syndrome: Human genome epidemiology review

FMR1 and the fragile X syndrome: Human genome epidemiology review

Practice parameter: Evaluation of the child with global developmental delay [RETIRED]

DNA Analysis of the Fragile X Syndrome in an at Risk Pediatric Population in Croatia: Simple Clinical Preselection Criteria Can Considerably Improve the Cost-Effectiveness of Fragile X Screening Studies

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