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Query: UMLS:C0025362 (mental retardation)
 15,878 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cases of nonspecific mental retardation (MR) born in British Columbia between 1952 and 1970 ascertained through the British Columbia Health Surveillance Registry were linked by birth registration number to family sibships from computer-linked groupings of birth and marriage records in British Columbia. It was possible to retrieve family information for 97% of the cases by this method. Because of good ascertainment and relatively large sample size, the 1952-1965 birth cohort comprising 2,209 index cases was selected for calculations of overall risks and recurrence risks to sibs categorized by sex, MR level, associated neurological disability, and singleton versus multiple birth. The overall risk of affected individuals among all sibs was 4.4 +/- 0.6%, which was about ten times greater than the minimum population incidence of nonspecific MR. The risk among subsequent sibs of the first affected case in a family was 3.7 +/- 0.8%. These risks varied depending on sex, MR level, and whether the mental retardation was associated with hydrocephalus, microcephalus, cerebral palsy, or epilepsy. The recurrence risk after two affected individuals was 12 +/- 7%--about three times greater than after one affected individual. Even though the frequency of MR is greater among twins than in the overall population, the recurrence risk of nonspecific MR was not significantly different for index cases from either singleton or multiple births.
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PMID:Sib risks for nonspecific mental retardation in British Columbia. 713 31

With the development of modern imaging techniques, disturbances of neuronal migration appear to be a major cause of epilepsy, mental retardation and chronic neurological disability in childhood. Sixty-nine cases are presented, including 46 of diffuse migration abnormalities and 23 of localized dysplasia. Patients with diffuse migration disorders presented with mental retardation, gross motor impairment and severe seizure disorders whereas in those with focal anomalies, epilepsy was the chief complaint. Magnetic resonance imaging, although usually diagnostic of migration disorders often does not allow definition of the pathologic type. Some EEG patterns, such as high amplitude fast rhythms or the theta-delta pattern are highly suggestive. Most cases of abnormal migration are sporadic and probably acquired. Some are due to chromosomal anomalies, especially of chromosome 17p where a gene for lissencephaly has been mapped. Familial cases occur with both recessive and possibly dominant inheritance. Epilepsy due to migration abnormalities is often intractable. Resection of dysplastic cortex may be effective for localized disease and callosotomy has been proposed for diffuse anomalies.
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PMID:The place of neuronal migration abnormalities in child neurology. 800 Sep 73