Assortative mating and parental genetic relatedness contribute to the pathogenicity of variably expressive variants

Corrine Smolen, Matthew Jensen, Lisa Dyer, Lucilla Pizzo, Anastasia Tyryshkina, Deepro Banerjee, Laura Rohan, Emily Huber, Laila El Khattabi, Paolo Prontera, Jean Hubert Caberg, Anke Van Dijck, Charles Schwartz, Laurence Faivre, Patrick Callier, Anne Laure Mosca-Boidron, Mathilde Lefebvre, Kate Pope, Penny Snell, Paul J. LockhartLucia Castiglia, Ornella Galesi, Emanuela Avola, Teresa Mattina, Marco Fichera, Giuseppa Maria Luana Mandarà, Maria Grazia Bruccheri, Olivier Pichon, Cedric Le Caignec, Radka Stoeva, Silvestre Cuinat, Sandra Mercier, Claire Bénéteau, Sophie Blesson, Ashley Nordsletten, Dominique Martin-Coignard, Erik Sistermans, R. Frank Kooy, David J. Amor, Corrado Romano, Bertrand Isidor, Jane Juusola, Santhosh Girirajan

Research output: Contribution to journalArticlepeer-review


We examined more than 97,000 families from four neurodevelopmental disease cohorts and the UK Biobank to identify phenotypic and genetic patterns in parents contributing to neurodevelopmental disease risk in children. We identified within- and cross-disorder correlations between six phenotypes in parents and children, such as obsessive-compulsive disorder (R = 0.32–0.38, p < 10−126). We also found that measures of sub-clinical autism features in parents are associated with several autism severity measures in children, including biparental mean Social Responsiveness Scale scores and proband Repetitive Behaviors Scale scores (regression coefficient = 0.14, p = 3.38 × 10−4). We further describe patterns of phenotypic similarity between spouses, where spouses show correlations for six neurological and psychiatric phenotypes, including a within-disorder correlation for depression (R = 0.24–0.68, p < 0.001) and a cross-disorder correlation between anxiety and bipolar disorder (R = 0.09–0.22, p < 10−92). Using a simulated population, we also found that assortative mating can lead to increases in disease liability over generations and the appearance of “genetic anticipation” in families carrying rare variants. We identified several families in a neurodevelopmental disease cohort where the proband inherited multiple rare variants in disease-associated genes from each of their affected parents. We further identified parental relatedness as a risk factor for neurodevelopmental disorders through its inverse relationship with variant pathogenicity and propose that parental relatedness modulates disease risk by increasing genome-wide homozygosity in children (R = 0.05–0.26, p < 0.05). Our results highlight the utility of assessing parent phenotypes and genotypes toward predicting features in children who carry rare variably expressive variants and implicate assortative mating as a risk factor for increased disease severity in these families.

Original languageEnglish (US)
Pages (from-to)2015-2028
Number of pages14
JournalAmerican Journal of Human Genetics
Issue number12
StatePublished - Dec 7 2023

All Science Journal Classification (ASJC) codes

  • Genetics
  • Genetics(clinical)

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