Original Investigations

Human Genetics

, Volume 48, Issue 1, pp 67-72

First online:

Down's syndrome in Western Australia: Cytogenetics and incidence

  • Marie T. MulcahyAffiliated withThe Cytogenetics Unit, State Health Laboratory Service, G.P.O.

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235 cases of Down's syndrome were ascertained in a 10-year study of Down's syndrome in Western Australia. Although cytogenetic studies performed on 222 subjects confirmed that 95% of cases were trisomic due to nondisjunction, 4% were trisomic due to translocation, and 1% were mosaic, the ratio of inherited/sporadic translocations differed from that usually reported. Comparison of the results with those of an earlier Australian survey of Down's syndrome demonstrated a real fall in the incidence of Down's syndrome in Australia but no significant change in maternal age-specific incidences.