title: Letter: Emigration and mental subnormality in Northern Ireland.
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D004314:Down Syndrome / Q000453:epidemiology* / Q000209:etiology / Q000235:genetics; D004641:Emigration and Immigration; D005260:Female; D005838:Genotype; D006801:Humans; D007178:Inbreeding; D008607:Intellectual Disability / Q000453:epidemiology* / Q000235:genetics; D008297:Male; D008875:Middle Aged; D009660:Northern Ireland; D012423:Rural Health; D014171:Transients and Migrants