SOX5 and 12p12.1 microdeletion syndrome: Lamb-Shaffer syndrome (LAMSHF) is a rare autosomal dominant neurodevelopmental disorder caused by haploinsufficiency of the SOX5 gene on chromosome 12p12.1 and characterized by global developmental delay, intellectual disability, speech and language impairment, and frequent behavioral disturbances, including autistic traits and attention deficits.