International Journal of Review Article The Recent Advances in Autism Genetics Serap Bilge* Department of Pediatric Neurology, Ministry of Health, Children Hospital of Diyarbakır/Diyarbakır, Turkey *Corresponding author: Serap Bilge, Department of Pediatric Neurology, Ministry of Health, Children Hospital of Diyarbakır/Diyarbakır, Turkey Received: February 13, 2023 Published: April 05, 2023 Copyright © All rights are reserved by Serap Bilge* Clinical Studies & Medical Case Reports ISSN 2692-5877 1 DOI: 10.46998/IJCMCR.2023.25.000610 DOI: 10.46998/IJCMCR.2023.25.000610 Abstract Autism Spectrum Disorder (ASD) is a highly heritable neurodevelopmental disorder characterized clinically by repetitive ste- reotyped behaviors, restricted interests, and impaired social and communication skills and it is defned as a developmental disorder. In the past years, autism was confused with other monogenic disorders because the fndings were similar. However, with the development of technology over the years, there have been many studies in the feld of autism. Recent studies show that there are rare variants of autism as well as small-efect gene variants. Rare variants have more impact than known variants. The discovery of rare variants challenges traditional diagnostic boundaries and demonstrates the heterogeneity of autism. Stud- ies on twins have proven that autism is one of the most common inherited disorders. In addition, it has been observed that the heritability rate of autism is lower in dizygotic twins compared to monozygotic twins. Based on the microarray, deletion and duplication analysis, single-molecule fuorescence hybridization methods, various mosaic mutations, microdeletions, microdu- plications, and mutations in CYFIP1, NIPA2, and UBE3A genes were found in autism. As a result of research not conducted at the molecular level, a broad spectrum of autism with mild symptoms has been found in families of individuals with autism. The likelihood of autism recurring due to various mutations is not known. Therefore, a genetic counselor should be consulted when planning a family. In summary, this review explains in detail how autism has been shaped by recent studies. Keywords: Autism Spectrum Disorder; Genetic; Recent Advances List of Abbreviations: DSM-5: Diagnostic and Statistical Manual of Mental Disorders; ICD-11: 11th Revision of the Inter- national Classifcation of Diseases; BAP: Broad Autism Spectrum; ASD: Autism Spectrum Disorder; AFHI: Autism Family History Interviews; GWAS: Genome-Wide Association Studies; cDNA: Complementary DNA; SNP: Single Nucleotide Poly- morphism; MLPA: Multiplex Ligation-dependent Probe Amplifcation; PCR: Polymerase Chain Reactions; mRNA: Messenger RNA; smFISH: Single Molecule Fluorescence Hybridization Introduction Autism Spectrum Disorder (ASD) is one of the most common developmental disorders today. ASD is seen in all racial and ethnic groups in the world, but there is no precise informa- tion about its prevalence, although it is stated that it has in- creased over the years. Today, the reason for the increase in the incidence of autism is estimated to be the increase in autism awareness, the broad determination of diagnostic criteria, and the early diagnosis methods becoming known. Inheritance of Autism in Twin Studies The concept of autism is more clearly defned by the clinical studies of Leo Kanner in 1943. Leo Kanner observed 11 chil- dren during this period and observed that each of the children showed language impairment and resistance to variability. He even called this condition early infancy autism, meaning "ex- treme loneliness", in an article published in those years. While the prevalence of autism was low in those years, today it is thought to afect 1% of the world population. While the preva- lence of autism in boys is 5 times higher than in girls, consider- ing this knowledge, it is estimated that 1 in 68 children have autism. Autism is referred to as ASD in DSM-5 and ICD-11. Since the causes of autism are quite diferent and are caused by mutations in various loci (gene regions), the range is quite wide. It is even confused with other monogenic disorders. Be- fore detailed research, Rett syndrome, a monogenic disorder, was thought to be typical autism seen only in females. How- ever, genetic tests show that a mutation in the MECP2 gene causes Rett syndrome. In addition, unlike autism, individu- als with Rett syndrome can make eye contact and cope with more severe autonomic nervous system disorders. In addition, monogenic disorders such as Tuberous Sclerosis and Fragile X syndrome can also present with autism symptoms and are often confused with autism. Some researchers describe these disorders as syndromal autism or high penetrance of autism. On the other hand, new genetic and biological fndings em- phasize that there is no clear-cut distinction between these rare disorders [1,2]. Kanner emphasizes that autism is congenital. In addition, ac- cording to a psychoanalytic understanding that emerged later, the cause of autism is seen as unloving mothers or "refrigerator mothers". To see the causes and efects of autism, research is being conducted on twin individuals. In these studies, twins