Lindsten J, Marsk L, Berglund K, Iselius L, Ryman N, Annerén G, Kjessler B, Mitelman F, Nordenson I, Wahlström J, Vejlens L
Hum Genet Suppl. 1981;2:195-210.
The incidence of Down's syndrome has been studied among children born in Sweden during the years 1968-1977. The risk for mothers of different ages of bearing such a child did not change during these years. This does not exclude that a change in incidence might have occurred in smaller areas of the country but escaped detection for statistical reasons. A higher than expected number of children with Down's syndrome were born in a few communities, which most likely is a chance event. No correlation could be detected between the incidence of Down's syndrome and a number of socioeconomic variables. The correlation with maternal age was studied in detail. There was a significant excess of males among both the newborn children with Down's syndrome and fetuses with trisomy 21 aborted after prenatal diagnosis. A similar tendency was found among the cases with a chromosome mosaicism but not among those with a translocation. Two hypotheses are put forward to explain the excess of males with trisomy 21.
1968年至1977年间，瑞典对出生儿童中的唐氏综合征发病率进行了研究。在此期间，不同年龄母亲生育此类患儿的风险并未改变。这并不排除该国较小地区的发病率可能发生了变化，但由于统计原因而未被发现。少数社区出生的唐氏综合征患儿数量高于预期，这很可能是偶然事件。未发现唐氏综合征发病率与一些社会经济变量之间存在相关性。对与母亲年龄的相关性进行了详细研究。唐氏综合征新生儿和产前诊断后流产的21三体胎儿中，男性明显过多。在染色体嵌合体病例中也发现了类似趋势，但在易位病例中未发现。提出了两种假设来解释21三体男性过多的现象。
