Children of consanguineous parents are at increased risk of mood disorders and psychoses

Reference

Maguire A, Tseliou F, O'Reilly D. Consanguineous marriage and the psychopathology of progeny. A population-wide data linkage study. JAMA Psychiatry 2018;75(5):438-446.

Synopsis

Consanguinity is defined by the union of individuals who are second cousins or closer. These investigators retrospectively reviewed data from a national registry in Northern Ireland comprising all births between January 1, 1971, and December 31, 1986, with linking data from additional national registries of primary care, prescription drug use, and death records. Birth registry data included gestational age, birth weight, delivery method, mother's age, parity, area of residence, father's age, and degree of consanguinity to the mother. Eligible individuals (N = 363,960) with full data available for all variables included 609 (0.2%) children born to consanguineous parents, including 349 and 260 to second-cousin and first-cousin parents, respectively. Significantly more children of first-cousin consanguineous unions were prescribed antidepressant or anxiolytic medications compared with children of nonrelated parents (35.8% vs 26.0%, respectively). Similarly, children of first-cousin consanguineous parents were significantly more likely to receive a prescription for antipsychotic medication than children of nonrelated parents (8.5% vs 2.7%). Rates of antidepressant, anxiolytic, and antipsychotic medication use were also increased in second-cousin consanguineous parents' offspring, but were not significant after adjustment for confounding risk factors, including prematurity, birth weight, mother's parity, parental age, deprivation, and rurality. Although the investigators were unable to obtain information on parental mental health, they speculate that the increased risk of poor mental health among these offspring is significantly high enough that mental health problems among their consanguineous parents would not be enough to explain the association—and, in any case, there is no evidence to suggest poorer mental health among consanguineous couples.