Lamb-Shaffer syndrome is caused by a partial or complete deletion of the SOX5 gene on chromosome 12p12 resulting in haploinsufficiency, and the occurrence of frame shift variants, splicing variants, nonsense variants and missense variants can also affect its haploinsufficiency effect and cause the disease [1, 4]. This evidence concerns the gene SOX5 and developmental and speech delay due to SOX5 deficiency.