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Currently, protein-coding de novo variants and large copy number variants have been identified as important for ~30% of individuals with autism. One approach to identify relevant variation in individuals who lack these types of events is by utilizing newer genomic technologies. In this study, highly accurate PacBio HiFi long-read sequencing was applied to a family with autism, epileptic encephalopathy, cognitive impairment, and mild dysmorphic features (two affected female siblings, unaffected parents, and one unaffected male sibling) with no known clinical variant. From our long-read sequencing data, a de novo missense variant in the KCNC2 gene (encodes Kv3.2) was identified in both affected children. This variant was phased to the paternal chromosome of origin and is likely a germline mosaic. In silico assessment revealed the variant was not in controls, highly conserved, and predicted damaging. This specific missense variant (Val473Ala) has been shown in both an ortholog and paralog of Kv3.2 to accelerate current decay, shift the voltage dependence of activation, and prevent the channel from entering a long-lasting open state. Seven additional missense variants have been identified in other individuals with neurodevelopmental disorders (p = 1.03 × 10 -5 ). KCNC2 is most highly expressed in the brain; in particular, in the thalamus and is enriched in GABAergic neurons. Long-read sequencing was useful in discovering the relevant variant in this family with autism that had remained a mystery for several years and will potentially have great benefits in the clinic once it is widely available., (© 2022 The Authors. American Journal of Medical Genetics Part A published by Wiley Periodicals LLC.)

Variations in MYT1L, a gene encoding a transcription factor expressed in the brain, have been associated with autism, intellectual disability, and schizophrenia. Here we provide an updated review of published reports of neuropsychiatric correlates of loss of function and duplication of MYT1L. Of 27 duplications all were partial; 33% were associated exclusively with schizophrenia, and the chromosomal locations of schizophrenia-associated duplications exhibited a distinct difference in pattern-of-location from those associated with autism and/or intellectual disability. Of 51 published heterozygous loss of function variants, all but one were associated with intellectual disability, autism, or both, and one resulted in no neuropsychiatric diagnosis. There were no reports of schizophrenia associated with loss of function variants of MYT1L (Fisher's exact p < .00001, for contrast with all reported duplications). Although the precise function of the various mutations remains unspecified, these data collectively establish the candidacy of MYT1L as a reciprocal mutation, in which schizophrenia may be engendered by partial duplications, typically involving the 3' end of the gene, while developmental disability-notably autism-is associated with both loss of function and partial duplication. Future research on the specific effects of contrasting mutations in MYT1L may provide insight into the causal origins of autism and schizophrenia., (© 2020 Wiley Periodicals, Inc.)

Objective: Recent epidemiologic studies worldwide have documented a rise in prevalence rates for autism spectrum disorders (ASD). Broadening of diagnostic criteria for ASD may be a major contributor to the rise in prevalence, particularly if superimposed on an underlying continuous distribution of autistic traits. This study sought to determine the nature of the population distribution of autistic traits using a quantitative trait measure in a large national population sample of children., Method: The Japanese version of the Social Responsiveness Scale (SRS) was completed by parents on a nationally representative sample of 22 529 children, age 6-15., Results: Social Responsiveness Scale scores exhibited a skewed normal distribution in the Japanese population with a single-factor structure and no significant relation to IQ within the normal intellectual range. There was no evidence of a natural 'cutoff' that would differentiate populations of categorically affected children from unaffected children., Conclusion: This study provides evidence of the continuous nature of autistic symptoms measured by the SRS, a validated quantitative trait measure. The findings reveal how paradigms for diagnosis that rest on arbitrarily imposed categorical cutoffs can result in substantial variation in prevalence estimation, especially when measurements used for case assignment are not standardized for a given population., (© 2012 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

While strong familial evidence supports a substantial genetic contribution to the etiology of autism spectrum disorders (ASD), specific genetic abnormalities have been identified in only a small minority of all cases. In order to comprehensively delineate the genetic components of autism including the identification of rare and common variants, overall sample sizes an order of magnitude larger than those currently under study are critically needed. This will require rapid and scalable subject assessment paradigms that obviate clinic-based time-intensive behavioral phenotyping, which is a rate-limiting step. Here, we test the accuracy of a web-based approach to autism phenotyping implemented within the Interactive Autism Network (IAN). Families who were registered with the IAN and resided near one of the three study sites were eligible for the study. One hundred seven children ascertained from this pool who were verbal, age 4-17 years, and had Social Communication Questionnaire (SCQ) scores > or =12 (a profile that characterizes a majority of ASD-affected children in IAN) underwent a clinical confirmation battery. One hundred five of the 107 children were ASD positive (98%) by clinician's best estimate. One hundred four of these individuals (99%) were ASD positive by developmental history using the Autism Diagnostic Interview-Revised (ADI-R) and 97 (93%) were positive for ASD by developmental history and direct observational assessment (Autism Diagnostic Observational Schedule or expert clinician observation). These data support the reliability and feasibility of the IAN-implemented parent-report paradigms for the ascertainment of clinical ASD for large-scale genetic research., ((c) 2010 Wiley-Liss, Inc.)

Recent research has suggested that the mode of inheritance for simplex autism (SA, one individual in the family affected) may be distinct from that for multiplex autism (MA, two or more individuals affected). Since sub clinical autistic traits have been observed in "unaffected" relatives of children with autism, we explored whether the distributions of such traits in families supported differential modes of genetic transmission for SA and MA autism. We measured patterns of familial aggregation of quantitative autistic traits (QAT) in children and parents in 80 SA families and 210 MA families, using the Social Responsiveness Scale. When considering all SA and MA siblings who scored below a uniform quantitative (clinical-level) severity threshold, MA brothers exhibited a distinct pathological shift in the distribution, compared to SA brothers (P < 0.0001). Such aggregation of QAT was also observed in fathers but not among females in MA families. Significant spousal correlations for QAT-suggestive of assortative mating-were observed in both SA and MA families, but neither group was characterized by a greater-than-chance level of concordant elevation among spousal pairs in this volunteer sample. Among male first degree relatives, there exist distinct patterns of QAT manifestation for simplex versus multiplex autism. These findings are consistent with the results of molecular genetic studies that have suggested differential modes of intergenerational transmission for SA and MA. Characterization of QAT and other endophenotypes among close relatives may be useful for reducing sample heterogeneity in future genetic and neurobiologic studies of autism., ((c) 2008 Wiley-Liss, Inc.)

Background: Disinhibitory personality traits such as high novelty seeking (NS) are moderately heritable, and individuals with substance use disorders (SUDs) frequently exhibit such traits. However, recent studies have cast doubt on the supposition that such traits are true familial risk factors for SUD and particularly for alcohol dependence. Another possibility is that familial risk interacts with personality-associated risk, in which case the association between personality and familial risk might depend on sample composition, accounting for the lack of consensus among studies to date. We examined this possibility by analyzing the association between NS and alcohol dependence in individuals at intermediate and high levels of familial risk for alcohol dependence., Methods: Data from the Collaborative Study on the Genetics of Alcoholism, a multisite family study, were examined. Subjects were 1,111 adult siblings of alcohol-dependent index cases. Parental diagnoses of alcohol dependence and personality scores of NS from the Tridimensional Personality Questionnaire were used to predict alcohol dependence., Results: A significant interaction between NS and familial risk for alcoholism was seen, such that NS was a significantly stronger predictor of alcohol dependence in subjects with one or more parents with alcohol dependence than in subjects without alcohol-dependent parents., Conclusions: Novelty seeking and familial risk interact so that the risk associated with high NS is magnified in families with parental alcohol dependence and NS is a moderator of familial risk. Accordingly, high NS is strongly associated with alcohol dependence in subjects with a parent diagnosed with alcohol dependence, but low NS may protect against the risk associated with familial alcoholism. This interaction may account for conflicting findings from studies that have examined this question previously.