SOBP is associated with syndromic and nonsyndromic intellectual disability. It carries a zinc-finger of the zf-C2H2 type at the N-terminus, and a highly characteristic C-terminal PhPhPhPhPhPh motif. The deduced 873-amino acid protein contains an N-terminal nuclear localisation signal (NLS), followed by 2 FCS-type zinc finger motifs, a proline-rich region (PR1), a putative RNA-binding motif region, and a C-terminal NLS embedded in a second proline-rich motif. SOBP is expressed in various human tissues, including developing mouse brain at embryonic day 14. In postnatal and adult mouse brain SOBP is expressed in all neurons, with intense staining in the limbic system. Highest expression is in layer V cortical neurons, hippocampus, pyriform cortex, dorsomedial nucleus of thalamus, amygdala, and hypothalamus. Postnatal expression of SOBP in the limbic system corresponds to a time of active synaptogenesis [2]. the family is also referred to as Jackson circler, JXC1. In seven affected siblings from a consanguineous Israeli Arab family with mental retardation, anterior maxillary protrusion, and strabismus mutations were found in this protein [1,2].

1: Autosomal recessive mental retardation syndrome with anterior maxillary protrusion and strabismus: MRAMS syndrome. Basel-Vanagaite L, Rainshtein L, Inbar D, Gothelf D, Hennekam R, Straussberg R; Am J Med Genet A. 2007;143:1687-1691. PMID:17618476

2: SOBP is mutated in syndromic and nonsyndromic intellectual disability and is highly expressed in the brain limbic system. Birk E, Har-Zahav A, Manzini CM, Pasmanik-Chor M, Kornreich L, Walsh CA, Noben-Trauth K, Albin A, Simon AJ, Colleaux L, Morad Y, Rainshtein L, Tischfield DJ, Wang P, Magal N, Maya I, Shoshani N, Rechavi G, Gothelf D, Maydan G, Shohat M, Basel-Vanagaite L; Am J Hum Genet. 2010;87:694-700. PMID:21035105