RESUMEN
The acromesomelic dysplasias (AMDs) are a group of genetic disorders that primarily affect the middle and distal segments of the extremities. A form of AMD is present on the isolated island of St Helena in the South Atlantic, which has a population of approximately 5500 derived from a number of founder individuals. DNA from four affected individuals and 11 first-degree relatives in four related nuclear families segregating an AMD was collected for gene mapping studies. Six consecutive markers on chromosome 9, spanning an approximately 5 cM region, showed identical homozygosity in all affected individuals, thus identifying a region of homozygosity by descent. Multipoint analysis generated a maximum lod score of Z = 2.85. These data localize the gene for this dysplasia to the pericentromeric region of chromosome 9 where the gene for the Maroteaux form of AMD is situated. The identification of the gene responsible for this disorder may shed further light on the complex processes involved in limb morphogenesis.
Asunto(s)
Mapeo Cromosómico , Cromosomas Humanos Par 9/genética , Homocigoto , Osteocondrodisplasias/genética , Alelos , Huesos/anomalías , Huesos/diagnóstico por imagen , Consanguinidad , ADN/análisis , ADN/sangre , Femenino , Ligamiento Genético/genética , Humanos , Escala de Lod , Masculino , Repeticiones de Microsatélite , Osteocondrodisplasias/diagnóstico por imagen , Linaje , RadiografíaAsunto(s)
Sordera/epidemiología , África Austral/epidemiología , Niño , Sordera/etiología , Sordera/genética , Femenino , Humanos , Recién Nacido , Masculino , Embarazo , Grupos RacialesRESUMEN
A study of 212 Indian children at the V.A. Naik School for Deaf was undertaken to determine the aetiology of their deafness. Undifferentiated autosomal recessive deafness was more frequent among Muslim patients--a population with a high incidence of consanguineous marriages--than among Tamils and Hindus. Although fewer than expected genetic syndromes were identified, Waardenburg's syndrome was present in 2% of the pupils. A firm diagnosis of acquired deafness was obtained in 32 children (15%).
Asunto(s)
Sordera/etnología , Adolescente , Niño , Preescolar , Sordera/epidemiología , Femenino , Humanos , India/etnología , Masculino , SudáfricaRESUMEN
An aetiological survey of 499 deaf Black children in 3 schools in Southern Africa is reported. Specific genetic syndromes were identified in 21 children, of whom 13 had the Waardenburg syndrome. Inherited deafness without associated defects was diagnosed in further 32 children, and an indentifiable acquired cause was evident in 108 children (22%). No cause could be found in the remaining 338 children (68%), of whom 71 had various nonspecific congenital anomalies.