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Genetic prognosis in severe mental handicap
Journal of Mental Deficiency Research
|September 1, 1975
Summary
This study surveyed 698 children with severe mental handicap, finding a significant portion lacked a clear cause. Accurate diagnosis is crucial for effective genetic counseling and determining recurrence risks in families.
Area of Science:
- Medical Genetics
- Pediatrics
- Neurology
Background:
- Severe mental handicap affects a significant number of children.
- Understanding the etiology is vital for genetic prognosis and counseling.
- Previous studies highlighted the challenges in diagnosing the causes of mental retardation.
Purpose of the Study:
- To survey children with severe mental handicap for genetic prognosis.
- To determine the incidence of mental retardation in siblings of affected children.
- To emphasize the importance of etiological diagnosis for genetic counseling.
Main Methods:
- Survey of 698 children (under 16, IQ <50) admitted between 1956-1959.
- Categorization of cases by suspected etiology (environmental, Down's syndrome, genetic syndromes, hydrocephalus, unclassified).
- Tracing families of 660 children to assess sibling incidence of mental retardation.
Main Results:
- Etiological breakdown: 23.7% environmental, 50.9% unclassified, 16.2% Down's syndrome, 5.3% other genetic syndromes, 3.9% congenital hydrocephalus.
- Sibling incidence varied by etiology: 1.1% (environmental) to 11.5% (other genetic syndromes).
- A high proportion of cases remained without a definitive etiological diagnosis.
Conclusions:
- A significant proportion of severe mental handicap cases lack a clear etiological diagnosis.
- Accurate diagnosis is essential for providing reliable genetic counseling.
- Recurrence risk for unclassified cases, excluding specific familial patterns, is approximately 3%.