Lamb-Shaffer syndrome (LSS) is characterized by intellectual disability, behavioral problems, microcephaly and facial dysmorphism. Strabismus, scoliosis and mild skeletal defects may be found in several individuals. LSS was reported in patients having small deletions in the short arm of chromosome 12 (12p12.1). Deletions in all these patients involved the SOX5 gene. Further examinations showed that point mutations in the SOX5 gene and balanced translocations with breakpoints in this area may produce the same clinical manifestations. The authors report six new patients with LSS. One of these patients had a point mutation in the SOX5 gene; five others had small deletions of 12p12.1. The size of these deletions ranged from 0.05 Mb to 0.2 Mb. Two adult males inherited this deletion from their father who had this deletion in the mosaic form. Neither of the patients in this group had defects of the internal organs. Clinical manifestations of the LSS may vary even within a family. The possibility of sub-clinical manifestations dictate the necessity of cytogenetic testing of the parents of an affected child even if these parents seem to be unaffected.
Innella G. et al. “Clinical spectrum and follow-up in six individuals with Lamb-Shaffer syndrome (SOX5)”. “Amer. J. Med. Genet.” 2021, v. 185 (2), 608-613.