Autism spectrum disorders in siblings of children with a developmental language disorder.

Little is known about the familial characteristics of children diagnosed during childhood as having a developmental language disorder (DLD). This study aimed to investigate the prevalence of autism spectrum disorders (ASD) in siblings of probands diagnosed during childhood as having a DLD. In order to estimate the prevalence of ASD, 908 siblings of 469 probands diagnosed during childhood as having a DLD, and 3,802 siblings of 2,345 controls from the general population, without a known history of DLD, were screened for ASD through the nationwide Danish Psychiatric Central Register (DPCR). The mean length of observation was 35.2 years and 34.8 years, respectively, and the mean age at follow-up 38.4 years and 37.4 years, respectively. At follow-up one sibling (0.1%) in the DLD case group and eight siblings (0.2%) in the comparison group were known in the DPCR with a diagnosis of any ASD (P = 0.53; OR = 0.52; 95%CI 0.07-4.19). Thus our results provide no support for a familial association between DLD and ASD.