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Novel NEXMIF pathogenic variant in a boy with severe autistic features, intellectual disability, and epilepsy, and his mildly affected mother


Intellectual disability (ID) and autism spectrum disorders are complex neurodevelopmental disorders occurring among all ethnic and socioeconomic groups. Pathogenic variants in the neurite extension and migration factor (NEXMIF) gene (formerly named KIAA2022) on the X chromosome are responsible for ID, autistic behavior, epilepsy, or dysmorphic features in males. Most affected females described had a milder phenotype or were asymptomatic obligate carriers. We report here for the first time mother-to-son transmission of a novel NEXMIF truncating variant without X-inactivation skewing in the blood. Truncating gene variant leads to symptomatic mother to severely affected son transmission. Our findings emphasize that NEXMIF sequencing should be strongly considered in patients with unexplained autism spectrum disorder, ID, and epilepsy, irrespective of gender. Such testing could increase our knowledge of the pathogenicity of NEXMIF variants and improve genetic counseling.

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The patients’ guardians gave written informed consent. We thank A. Dayer for his continuous support and interest. We thank the patients and their families for participating in the study. NL was supported by the NCCR Synapsy (Swiss National Science Foundation).

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Correspondence to Nelle Lambert.

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Lambert, N., Dauve, C., Ranza, E. et al. Novel NEXMIF pathogenic variant in a boy with severe autistic features, intellectual disability, and epilepsy, and his mildly affected mother. J Hum Genet 63, 847–850 (2018).

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