UNASSIGNED: To assess consanguinity as a probable risk factor for congenital ptosis.
UNASSIGNED: In this case-control study, 97 patients with congenital ptosis and 97 participants as the control group were included. The age, sex, and residence area of the control group were matched with the cases. The inbreeding coefficient (F) was calculated for each participant, and the mean of the inbreeding coefficient (α) was calculated for each group.
UNASSIGNED: The prevalence of consanguineous marriage in parents of cases with congenital ptosis and those of the control group was 54.6% and 30.9%, respectively (P < 0.002). The mean of the inbreeding coefficient (α) in patients with ptosis was 0.026, whereas it was 0.016 in the control group (T = 2.51, degree of freedom = 192, P = 0.0129).
UNASSIGNED: The rate of consanguineous marriage was significantly higher among the parents of patients with congenital ptosis. It implies a probable recessive pattern in the etiology of congenital ptosis.

Relationship inference in a population is of interest for many areas of research from anthropology to genetics. It is possible to directly infer the relationship between the two individuals in a couple from their genetic data or to indirectly infer it from the genetic data of one of their offspring. For this reason, one can wonder if it is more advantageous to sample couples or single individuals to study relationships of couples in a population. Indeed, sampling two individuals is more informative than sampling one as we are looking at four haplotypes instead of two, but it also doubles the cost of the study and is a more complex sampling scheme. To answer this question, we performed simulations of 1000 trios from 10 different relationships using real human haplotypes to have realistic genome-wide genetic data. Then, we compared the genome sharing coefficients and the relationship inference obtained from either a pair of individuals or one of their offspring using both single-point and multi-point approaches. We observed that for relationships closer than 1st cousin, pairs of individuals were more informative than one of their offspring for relationship inference, and kinship coefficients obtained from single-point methods gave more accurate or equivalent genome sharing estimations. For more remote relationships, offspring were more informative for relationship inference, and inbreeding coefficients obtained from multi-point methods gave more accurate genome sharing estimations. In conclusion, relationship inference on a parental pair or on one of their offspring provides complementary information. When possible, sampling trios should be encouraged as it could allow spanning a wider range of potential relationships.