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Minor malformations in mental retardation of various aetiology
Insights
Children with genetic causes of intellectual disability have more minor malformations. Environmental factors are linked to fewer malformations, suggesting prenatal onset for genetic intellectual disability.
Area of Science:
- Medical Genetics
- Developmental Pediatrics
- Clinical Psychology
Background:
- Intellectual disability (ID) is a complex neurodevelopmental disorder with diverse etiologies.
- Minor malformations can be indicators of underlying genetic or environmental influences on development.
- Understanding the association between malformations and ID etiology is crucial for diagnosis and prognosis.
Purpose of the Study:
- To investigate the frequency and patterns of minor malformations in children with intellectual disability based on probable etiology.
- To compare malformation rates between different etiological groups of intellectual disability and a control group.
Main Methods:
- A case-control study involving 246 children with intellectual disability (IQ 37-67) and 1000 newborn controls.
- Patients were categorized into four groups: Down syndrome, other genetic causes, environmental damage, and unknown etiology.
- Minor malformations were systematically assessed and quantified per subject.
Main Results:
- Patients with Down syndrome exhibited the highest mean number of minor malformations (3.38), followed by other genetic causes (2.00).
- Mentally handicapped children with unknown (0.88) or environmental (0.37) etiology had significantly fewer malformations.
- Multiple minor anomalies were prevalent in genetically determined conditions, contrasting with the exogenic group.
Conclusions:
- The presence of minor malformations, particularly multiple ones, strongly suggests a prenatal origin for intellectual disability.
- Etiological classification is critical, as genetic factors are associated with a higher burden of minor anomalies in ID.
- This study reinforces the diagnostic value of minor malformations in identifying the developmental origins of intellectual disability.
Abstract:
The frequency of minor malformations was determined in 246 mentally retarded children with an I. Q. ranging from 37 to 67. According to the probable aetiology, the patients were divided into 4 groups: Down syndrome (n = 29), other genetic causes (n = 22), perinatal and postnatal environmental damages (n = 68), and unknown aetiology (n = 127). One thousand consecutive newborn infants served as controls. The mean number of minor malformations per subject was the highest in patients with Down syndrome (3.38) and other genetic disorders (2.00). It was significantly lower in the mentally handicapped of unknown (0.88) and of environmental origin (0.37). The number of multiple minor anomalies was high in the genetically determined conditions and the smallest and nearing the control value in the exogenic group. The results support the idea that the presence of minor malformations, and especially of multiple ones, refers to the prenatal onset of mental deficiency.