Genetic Testing of Neurodevelopmental Disorders in Israel.

Importance: Genetic testing is the criterion standard for diagnosing neurodevelopmental disorders (NDDs), with chromosomal microarray analysis (CMA) used as a first-line test for autism, intellectual disability, or global developmental delay. Despite advancements in genetic testing technologies and integration into health care systems, data on clinical use remain limited. Objective: To evaluate genetic counseling and testing rates in patients with major NDDs and these individuals' clinical and sociodemographic characteristics. Design, Setting, and Participants: This longitudinal, retrospective, population-based cohort study analyzed electronic health records of individuals born between 2000 and 2020 and insured by Clalit Health Services, the largest health maintenance organization in Israel. Follow-up extended through December 6, 2023. Patients diagnosed with autism spectrum disorder, intellectual disability or global developmental delay, epilepsy, or cerebral palsy (major NDDs) were included. Exposure: Neurodevelopmental disorders. Main Outcomes and Measures: The outcome was the rate of genetic counseling, CMA testing, and NDD diagnosis measured using descriptive statistics. Results: Of 2 406 763 individuals born in Israel between 2000 and 2020, 25 403 (1.06%; mean [SD] age at December 6, 2023, 11.9 [4.3] years; 68.7% male) were diagnosed with a major NDD. The cohort was predominantly of middle socioeconomic status (56.5%), and autism was the most common diagnosis (40.6%). Among 18 709 children indicated for CMA (ie, those with autism, intellectual disability or global developmental delay, or multiple diagnoses), 7233 (38.7%) received genetic counseling, and 4592 (24.5%) underwent testing (63.5% of those counseled). Genetic testing rates were higher in children with multiple co-occurring NDDs (1478 of 4005 [36.9%]) compared with those with autism alone (2189 of 10 311 [21.2%]). Genetic counseling rates were lowest for cerebral palsy and epilepsy as guidelines were less established. Genetic evaluation rates increased with more recent birth cohorts. While evaluation rates were similar across subpopulations for children with a diagnosis, initial autism diagnosis rates were 54% to 83% lower in lower socioeconomic status and minority populations, limiting access to counseling and testing. Conclusions and Relevance: A key finding of this cohort study was that more than one-third of patients who received genetic counseling did not undergo testing. Furthermore, low socioeconomic status and minority populations experienced drastic underdiagnosis of autism. These findings underscore the need for national initiatives to improve awareness and access to counseling and testing for all major NDDs and the recognition of autism in minority groups.