Autosomal recessive neurodevelopmental disorders (NDDs), where genetic alterations affect both copies of the gene, are less frequent in Germany than autosomal dominant de novo mutations. In populations with high rates of endogamy, though, they are the most important cause of NDDs. In families with consanguineous parents the approach of autozygosity- (aka homozygosity) mapping followed by genome sequencing has proven exceptionally successful in identifying the causative variants. This is especially important, as in these cases entail a recurrence risk of 25% in future pregnancies. In systematic studies groups at the Institute investigate such families in close collaboration with different genetic centres around the world. Many publications describing novel genes as well as contributing to the clinical characterization of known ones were made during the last years including Reuter et al. 2017, Buchert et al. 2016, Smogavec et al. 2016, Boycott et al. 2015 und Abou Jamra et al. 2011.