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Institutional screening for the fragile X syndrome
R Hagerman1, R Berry, A W Jackson
1Child Development Unit Children's Hospital, Denver, CO 80218.
American Journal of Diseases of Children (1960)
|November 1, 1988
Summary
Fragile X (fra[X]) chromosome screening helps identify intellectual disability patients needing genetic counseling. Specific physical traits in males, like large ears and macroorchidism, predict fra[X] syndrome.
Area of Science:
- Medical Genetics
- Clinical Cytogenetics
- Developmental Disabilities
Background:
- Fragile X (fra[X]) syndrome is a significant genetic cause of intellectual disability.
- Previous studies indicate a fra[X] prevalence of up to 6% in institutionalized males with intellectual disability.
- Predictive physical and behavioral markers for fra[X] syndrome require clarification due to overlapping features with other intellectual disability populations.
Purpose of the Study:
- To identify physical and cytogenetic predictors of the fragile X chromosome in patients with intellectual disability.
- To determine the prevalence of the fragile X chromosome in a regional center population.
- To assess the utility of cytogenetic screening for fra[X] syndrome in clinical settings.
Main Methods:
- Physical and cytogenetic examinations were conducted on 440 patients with intellectual disability.
- Karyotyping was performed to detect chromosomal abnormalities, specifically the fragile X chromosome.
- Specific physical measurements (ear length, testicular volume) and behavioral observations (hand biting) were recorded for males.
Main Results:
- Abnormal karyotypes were found in 6.3% (28/440) of patients.
- Eleven patients (2.5%) demonstrated the fragile X chromosome (seven males, four females).
- Predictive physical features in males included ear length ≥7.0 cm, macroorchidism ≥30 mL, and hand calluses/lesions from biting. The fra[X] chromosome was not found in spastic quadriplegic patients. All seven males with fra[X] were ambulatory and in higher-functioning units.
Conclusions:
- Cytogenetic screening for the fragile X chromosome is valuable for identifying individuals who may benefit from genetic counseling and treatment.
- Specific physical characteristics can serve as predictors for the fragile X syndrome in males with intellectual disability.
- The fragile X chromosome was identified in 2.5% of the studied population, highlighting the importance of screening in relevant patient groups.