I may be being silly...

[wormatron]

I was wondering whether Trisomy 21 or Down's Syndrome affects only Caucasians as I have never seen an African American or African Caribbean with this genetic disorder. I may be being naive. If so I hope my ignorance does not offend.

[Clanad]

This article, along with other's indicates the defect is present in all races, however may be under-reported:

Department of Human Genetics and Developmental Biology, Faculty of Medicine, University of Pretoria, Republic of South Africa.

Early reports indicated a low prevalence of Down's syndrome (DS) in black African children. More recent research demonstrates an incidence similar to, or higher than that reported to occur in First World populations. One of the possible reasons for underreporting of DS in Africa, appears to be the lack of recognition of the problem at birth. In this study, the musculoskeletal, central nervous system and craniofacial features are documented in 40 black DS neonates and 50 black control neonates without DS, and the findings are compared with those from a reported series of 37 caucasian DS and 40 healthy newborns. Musculoskeletal and central nervous system features were markedly similar in black and caucasian infants. However, the craniofacial features of the African DS newborns approximated more closely those of the normal African neonates, than was the case in the caucasian DS and normal neonates. This finding may partially explain the underreporting of DS in this population, and it emphasizes the need for a clinical awareness of DS and for complete clinical examination to identify affected infants.

PMID: 7555887 [PubMed - indexed for MEDLINE]