A study of sex-specific genetic effects underlying risk of orofacial clefts also highlights the potential impact of sequencing errors due to short read mis-mapping.

Orofacial clefts (OFCs), including cleft lip (CL), cleft palate (CP), and cleft lip with cleft palate (CLP), are among the most common craniofacial malformations in humans, with a birth prevalence of approximately 1 in 1,000 live births globally. Non-syndromic forms of OFC are predominantly genetic, with significant variability in prevalence across populations. Understanding the genetic underpinnings of OFCs remains a key public health priority, given the substantial medical and societal burden of these conditions. Recent genome-wide association studies (GWAS) have implicated numerous genetic loci, but challenges remain due to genetic heterogeneity and complex gene-environment interactions. This study aimed to identify sex-specific genetic risk factors for cleft lip with or without cleft palate (CL/P) through a meta-analysis of whole genome sequencing (WGS) data from 1,922 case-parent trios across eight diverse cohorts. Our approach revealed four SNPs in three distinct regions that showed genome-wide significant sex-specific effects. However, despite each of these SNPs passing standard quality control filters, follow-up analyses showed that these signals most likely were technical artifacts caused by sequencing errors, in particular mis-mapped reads due to sequence similarities with the sex chromo-somes. These findings highlight the necessity for careful scrutiny when studying differences between the sexes in genetic association studies.