The PQBP1 (polyglutamine tract-binding protein 1) gene encodes a nuclear protein that regulates pre-mRNA splicing and transcription. Mutations in the PQBP1 gene were reported in several X chromosome-linked mental retardation disorders including Golabi-Ito-Hall syndrome. The missense mutation that causes this syndrome is unique among other PQBP1 mutations reported to date because it maps within a functional domain of PQBP1, known as the WW domain. The mutation substitutes tyrosine 65 with cysteine and is located within the conserved core of aromatic amino acids of the domain. We show here that the binding property of the Y65C-mutated WW domain and the full-length mutant protein toward its cognate proline-rich ligands was diminished. Furthermore, in GolabiIto-Hall-derived lymphoblasts we showed that the complex between PQBP1-Y65C and WBP11 (WW domain-binding protein 11) splicing factor was compromised. In these cells a substantial decrease in pre-mRNA splicing efficiency was detected. Our study points to the critical role of the WW domain in the function of the PQBP1 protein and provides an insight into the molecular mechanism that underlies the X chromosome-linked mental retardation entities classified globally as Renpenning syndrome.

Background This study sought to characterize the donor-site complications associated with the osteocutaneous radial forearm free flap (ORFFF) used for mandibular reconstruction, as well as to compare donor-site complications between the ORFFF and fasciocutaneous radial forearm free flap (FRFFF). Methods An Institution Review Board approved, retrospective review identified all ORFFF and FRFFF performed for head and neck reconstruction with a single otolaryngology surgeon at an academic medical center over a 3-year period. Patients requiring an ORFFF underwent harvest of half of the diaphyseal diameter of the radius with prophylactic plating performed by hand surgeons. Donor-site outcomes including infection, skin graft loss, tendon exposure, neuropathy, radius fracture, hardware complications, and need for additional donor-site surgery were compared. Results In this study, 25 patients underwent ORFFF harvest, and 52 underwent FRFFF harvest. There was one radius fracture occurring in association with a hardware infection requiring reoperation. No fractures or other major donor-site complications were seen in the FRFFF group. Similar rates of minor complications were noted with skin graft take less than 50% in 4% (n = 1) and 8% (n = 4) with ORFFF and FRFFF, respectively, and tendon exposure in 8% (n = 2) and 15% (n = 8) with ORFFF and FRFFF, respectively. No soft tissue infections or sensory neuropathies were seen. Mean follow-up was 14.2 months for the ORFFF group and 11.7 months for the FRFFF group. Conclusion The risk of fracture following ORFFF harvest with prophylactic plating is small. Other donor-site complication rates were similar with both flap techniques.

Comparison between four different nerve transfers -spinal accessory nerve, intercostal nerve, motor fascicles of the median and ulnar nervehas not clearly indicated a better alternative over the others.