Egypt – consangunity rates, 1979-81

March 5, 2011

From Consanguinity and incidence of thalassaemia in Egypt:

“Of the 505 parental couples 177 were first cousins, i.e. 23% [23.2%]. Among the probands 91 were married and 13 of them to first cousins, i.e. 14% [14.4%]. The difference is not statistically significant (0.05<P<0.1) but may indicate a secular downward trend in the incidence of first-cousing marriages in Egypt….

The inbreeding coefficient (F1) of a first-cousin marriage is 1/16 or 0.0625. Consequently, the F1 of the probands' parental generation is 117/505 x 0.0625 or 0.0145 and for the married probands 13/91 x 0.0625 or 0.0089. For the following calculations we have used a weighted average of the two inbreeding coefficients, which is F1 = 0.0137."

First cousin marriages, parents = 23.2%
First cousin marriages, probands = 14.4%
First cousin marriages, total (weighted average) = 18.4%

Inbreeding coefficient = 0.0137 (weighted average)

Note that consang.net uses the figure of 0.0145 for the inbreeding coefficient, i.e. the number for just the parents, not including the probands.

Collection period: 1979-81
Study population: University/work survey; health clinic survey.
Sample size: 505 probands + 505 parental couples
Location: Cairo. The authors believed the samples to be representative, despite the fact that all the individuals currently lived in Cairo, since many of them had been born in other Delta/Nile Governorates. However, 132 of the male probands were students at Cairo University and another 74 (male and female) were employees at a corporation. These 206 individuals may not be representative of the population of Egypt on the whole (i.e. they may have above average IQs and, therefore, possibly were less likely to come from inbred families). 299 of the probands (female) were outpatients at gynecological clinics and, therefore, are likely more representative. *Note: the study does not include the Frontier Governorates.

see also consang.net.

~ ~ ~ ~ ~

So far then:

1979-81 – First cousin marriages = 18.4%
2000 – First cousin marriages = 21.8%
2008 – First cousin marriages = 15.6%

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