Incidence and epidemicity of Down's syndrome.
D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D004314:Down Syndrome / Q000453:epidemiology*; D006506:Hepatitis A / Q000453:epidemiology; D006801:Humans; D007223:Infant; D010507:Periodicity; D012621:Seasons; D006113:United Kingdom