Homozygous mutation of STXBP5L explains an autosomal recessive infantile-onset neurodegenerative disorder

作者：Kumar Raman; Corbett Mark A; Smith Nicholas J C; Jolly Lachlan A; Tan Chuan; Keating Damien J; Duffield Michael D; Utsumi Toshihiko; Moriya Koko; Smith Katherine R; Hoischen Alexander; Abbott Kim; Harbord Michael G; Compton Alison G; Woenig Joshua A; Arts Peer; Kwint Michael; Wieskamp Nienke; Gijsen Sabine; Veltman Joris A; Bahlo Melanie; Gleeson Joseph G; Haan Eric; Gecz Jozef^*

来源：Human Molecular Genetics, 2015, 24(7): 2000-2010.

DOI：10.1093/hmg/ddu614

We report siblings of consanguineous parents with an infantile-onset neurodegenerative disorder manifesting a predominant sensorimotor axonal neuropathy, optic atrophy and cognitive deficit. We used homozygosity mapping to identify an similar to 12-Mbp interval identical by descent (IBD) between the affected individuals on chromosome 3q13.13-21.1 with an LOD score of 2.31. We combined family-based whole-exome and whole-genome sequencing of parents and affected siblings and, after filtering of likely non-pathogenic variants, identified a unique missense variant in syntaxin-binding protein 5-like (STXBP5L c.3127G>A, p.Val1043Ile [CCDS43137.1]) in the IBD interval. Considering other modes of inheritance, we also found compound heterozygous variants in FMNL3 (c.114G>C, p.Phe38Leu and c.1372T>G, p.Ile458Leu [CCDS44874.1]) located on chromosome 12. STXBP5L (or Tomosyn-2) is expressed in the central and peripheral nervous system and is known to inhibit neurotransmitter release through inhibition of the formation of the SNARE complexes between synaptic vesicles and the plasma membrane. FMNL3 is expressed more widely and is a formin family protein that is involved in the regulation of cell morphology and cytoskeletal organization. The STXBP5L p. Val1043Ile variant enhanced inhibition of exocytosis in comparison with wild-type (WT) STXBP5L. Furthermore, WT STXBP5L, but not variant STXBP5L, promoted axonal outgrowth in manipulated mouse primary hippocampal neurons. However, the FMNL3 p.Phe38Leu and p.Ile458Leu variants showed minimal effects in these cells. Collectively, our clinical, genetic and molecular data suggest that the IBD variant in STXBP5L is the likely cause of the disorder.

• 出版日期2015-4-1
• 单位河北医科大学