A newly identified mutation in the PEX26 gene is associated with a milder form of Zellweger spectrum disorder

Cold Spring Harb Mol Case Stud. 2019 Feb 1;5(1):a003483. doi: 10.1101/mcs.a003483. Print 2019 Feb.

Abstract

Using clinical exome sequencing (ES), we identified an autosomal recessive missense variant, c.153C>A (p.F51L), in the peroxisome biogenesis factor 26 gene (PEX26) in a 19-yr-old female of Ashkenazi Jewish descent who was referred for moderate to severe hearing loss. The proband and three affected siblings are all homozygous for the c.153C>A variant. Skin fibroblasts from this patient show normal morphology in immunostaining of matrix proteins, although the level of catalase was elevated. Import rate of matrix proteins was significantly decreased in the patient-derived fibroblasts. Binding of Pex26-F51L to the AAA ATPase peroxins, Pex1 and Pex6, is severely impaired and affects peroxisome assembly. Moreover, Pex26 in the patient's fibroblasts is reduced to ∼30% of the control, suggesting that Pex26-F51L is unstable in cells. In the patient's fibroblasts, peroxisome-targeting signal 1 (PTS1) proteins, PTS2 protein 3-ketoacyl-CoA thiolase, and catalase are present in a punctate staining pattern at 37°C and in a diffuse pattern at 42°C, suggesting that these matrix proteins are not imported to peroxisomes in a temperature-sensitive manner. Analysis of peroxisomal metabolism in the patient's fibroblasts showed that the level of docosahexaenoic acid (DHA) (C22:6n-3) in ether phospholipids is decreased, whereas other lipid metabolism, including peroxisomal fatty acid β-oxidation, is normal. Collectively, the functional data support the mild phenotype of nonsyndromic hearing loss in patients harboring the F51L variant in PEX26.

Keywords: sensorineural hearing impairment; very long chain fatty acid accumulation.

Publication types

  • Case Reports
  • Research Support, Non-U.S. Gov't

MeSH terms

  • ATPases Associated with Diverse Cellular Activities / metabolism
  • Amino Acid Sequence
  • Female
  • Hearing Loss / genetics*
  • Hearing Loss / metabolism
  • Humans
  • Membrane Proteins / chemistry
  • Membrane Proteins / genetics*
  • Membrane Proteins / metabolism
  • Mutation, Missense*
  • Pedigree
  • Peroxisomes / metabolism*
  • Protein Binding
  • Protein Stability
  • Sequence Analysis, DNA
  • Syndrome
  • Young Adult
  • Zellweger Syndrome / genetics*
  • Zellweger Syndrome / metabolism

Substances

  • Membrane Proteins
  • PEX26 protein, human
  • ATPases Associated with Diverse Cellular Activities
  • PEX1 protein, human
  • PEX6 protein, human