Genetic Heterogeneity of Autism Spectrum Disorder: Identification of Five Novel Mutations (RIMS2, FOXG1, AUTS2, ZCCHC17, and SPTBN5) in Iranian Families via Whole-Exome and Whole-Genome Sequencing.

Researchers studied the genes of four families from Iran who have children with autism. They found five new genetic changes that hadn't been seen before in autism. Each family had different genetic problems - some had missing pieces of genes, others had changes that stopped genes from working properly. This shows that autism can be caused by many different genetic issues, which helps explain why autism affects people so differently.

This genetic study used advanced sequencing techniques to analyze four Iranian families with autism spectrum disorder (ASD). Researchers identified five novel genetic mutations in different genes (RIMS2, FOXG1, AUTS2, ZCCHC17, and SPTBN5) that had not been previously described in ASD. Each family showed distinct genetic alterations, including large deletions, nonsense mutations, and splicing variants. The mutations were confirmed through multiple validation methods including Sanger sequencing and computational modeling.

These findings demonstrate the significant genetic diversity underlying ASD and highlight how different genetic mechanisms can lead to similar clinical presentations. The study contributes to understanding the complex genetic architecture of autism.

These findings support the use of comprehensive genetic testing in ASD diagnosis and highlight the potential for personalized treatment approaches. The identification of novel mutations expands genetic testing panels and may improve diagnostic yield. Results emphasize the importance of individualized genetic counseling for families.

Small sample size of only four families limits generalizability. Functional validation of mutations was primarily computational rather than experimental. Long-term clinical outcomes and treatment responses were not assessed. Findings specific to Iranian population may not apply to other ethnicities.

Autism Spectrum Disorder (ASD) is a neurodevelopmental disorder characterized by abnormal social interactions, verbal communication difficulties, and restricted repetitive behaviors. Identifying the underlying genetic factors is crucial because of the complex genetic and environmental etiology. In this study, we performed whole-exome sequencing (WES), whole-genome sequencing (WGS), and array comparative genomic hybridization (aCGH) of four Iranian families with ASD-related conditions to identify novel genomic alterations. Five previously undescribed mutations were identified in these families.

Family 1: A homozygous 290.7 kb deletion CNV (chr8:103,652,204-103942926; hg38) encompassing exons 2-16 of RIMS2 (NM_001348484), confirmed in a 7-year-old male proband with developmental delay and cone-rod synaptic disorder. Family 2: A heterozygous nonsense mutation in FOXG1 (NM_005249.5:c.839C > A; p.Ser280Ter) in a 6-year-old female with Rett-like features, resulting in a truncated protein lacking corepressor domains. Family 3: A splice donor site mutation in AUTS2 (NM_015570.4:c.742 + 1G > C) in a 10-year-old female with ASD and Attention-deficit/hyperactivity disorder, generating a frameshift and premature stop codon affecting mRNA-binding functionality. Family 4: A heterozygous nonsense mutation in ZCCHC17 (NM_016505.4:c.220C > T; p.Arg74Ter) and a splicing variant in SPTBN5 (NM_016642.4:c.3470 + 2T > A) in two male siblings with ASD were predicted to result in truncated proteins and aberrant splicing.

Pathogenicity was supported through in silico analyses and structural modeling using I-TASSER, and segregation was confirmed using Sanger sequencing. This study highlights the genetic diversity of ASD and underscores the importance of advanced sequencing technologies in identifying novel mutations. Our findings contribute to the growing body of knowledge regarding the genetic basis of ASD, paving the way for personalized treatment strategies and early diagnosis.