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Summary: MGA (OMIM: 616061) encodes a dual-specificity transcription factor that regulates the expression of Max-network and T-box family target genes, important in embryogenesis. Previous studies have linked MGA to various phenotypes, including neurodevelopmental disorders, congenital heart disease, and early-onset Parkinson’s disease. Here, we describe the clinical phenotype of individuals with de novo, heterozygous predicted loss-of-function variants in MGA, suggesting a unique disorder involving both neurodevelopmental and congenital anomalies. In addition to developmental delays, certain congenital anomalies were present in all individuals in this cohort including cardiac anomalies, male genital malformations, and craniofacial dysmorphisms. Additional findings seen in multiple individuals in this cohort include hypotonia, abnormal brain imaging, hearing loss, sleep dysfunction, urinary issues, skeletal abnormalities, and feeding difficulties. These findings provide support for MGA as a gene intolerant to protein truncation with a broad phenotypic spectrum.

IntroductionPeople with Prader-Willi syndrome (PWS) have a distinctive behavioral phenotype that includes intellectual disability, compulsivity, inattention, inflexibility and insistence on sameness. Inflexibility and inattention are at odds with the cognitive flexibility and attention to social cues needed to accurately perceive the social world, and implicate problems in social cognition. This study assessed two social cognition domains in people with PWS; emotion recognition and social perception. We identified changes in social cognition over an approximate two-year time period (M = 2.23 years), relative strengths and weakness in social cognition, and correlates and predictors of social cognition.MethodsEmotion recognition and social perception were examined at two time points in 94 individuals with PWS aged 5 to 62 years (M = 13.81, SD = 10.69). Tasks administered included: standardized IQ testing; parent-completed measures of inattention and inflexibility; standard emotion recognition photos (fear, sadness, anger, happy); and videotaped social perception vignettes depicting negative events with either sincere/benign or insincere/hostile interactions between peers.ResultsAn atypical trajectory of negative emotion recognition emerged, marked by similar levels of poor performances across age, and confusion between sad and anger that is typically resolved in early childhood. Recognition of sad and fear were positively correlated with IQ. Participants made gains over time detecting social cues, but not in forming correct conclusions about the intentions of others. Accurately judging sincere intentions remained a significant weakness over time. Relative to sincere intentions, participant's performed significantly better in detecting negative social cues, and correctly judging trickery, deceit and lying. Age, IQ, inattention, and recognition of happy and sad accounted for 29% of variance in social perception.ConclusionMany people with PWS have deficits in recognizing sad, anger and fear, and accurately perceiving the sincere intentions of other people. The impact of these deficits on social behavior and relationships need to be better understood.