They will vary because understandings of consanguinity will vary.
High rates of affected siblings and parental consanguinity in some cases suggested that novel genetic immunodeficiencies might be involved.
The importance of parental consanguinity is often overestimated.
The rate of second cousin marriage was very low, and so also were those of first cousin once removed and more distant consanguinity.
Rather, the rates were based on consanguinity, or the relationship of the legatee to the deceased.
Most of the family studies show a small increase, about two-fold, in parental consanguinity.
For different degrees of consanguinity, the estimated percentages of first, second and third cousin marriages are quite similar.
At worst, the information merely notes consanguinity of parents, and notes relatives with similar symptoms.
