Yunis-Varón syndrome caused by biallelic VAC14 mutations

Eur J Hum Genet. 2017 Sep;25(9):1049-1054. doi: 10.1038/ejhg.2017.99. Epub 2017 Jun 21.

Abstract

Yunis-Varón syndrome (YVS) is an autosomal recessive disorder comprising skeletal anomalies, dysmorphism, global developmental delay and intracytoplasmic vacuolation in brain and other tissues. All hitherto-reported pathogenic variants affect FIG4, a lipid phosphatase involved in phosphatidylinositol (3,5)-bisphosphate [PtdIns(3,5)P2] metabolism. FIG4 interacts with PIKfyve, a lipid kinase, via the adapter protein VAC14; all subunits of the resulting complex are essential for PtdIns(3,5)P2 synthesis in the endolysosomal membrane compartment. Here, we present the case of a female neonate with clinical features of YVS and normal FIG4 sequencing; exome sequencing identified biallelic rare coding variants in VAC14. Cultured patient fibroblasts exhibited a YVS-like vacuolation phenotype ameliorated in a dose-dependent fashion by ML-SA1, a pharmacological activator of the lysosomal PtdIns(3,5)P2 effector TRPML1. The patient developed a diffuse leukoencephalopathy with loss of the normal N-acetylaspartate spectrographic peak and presence of a large abnormal peak consistent with myoinositol. We report that VAC14 is a second gene for Yunis-Varón syndrome.

Publication types

  • Case Reports

MeSH terms

  • Alleles
  • Cells, Cultured
  • Cleidocranial Dysplasia / diagnosis
  • Cleidocranial Dysplasia / genetics*
  • Ectodermal Dysplasia / diagnosis
  • Ectodermal Dysplasia / genetics*
  • Female
  • Fibroblasts / cytology
  • Fibroblasts / drug effects
  • Fibroblasts / metabolism
  • Humans
  • Infant, Newborn
  • Inositol / metabolism
  • Intracellular Signaling Peptides and Proteins
  • Limb Deformities, Congenital / diagnosis
  • Limb Deformities, Congenital / genetics*
  • Membrane Proteins / genetics*
  • Membrane Proteins / metabolism
  • Micrognathism / diagnosis
  • Micrognathism / genetics*
  • Mutation*
  • Phenotype
  • Phthalimides / pharmacology
  • Quinolines / pharmacology
  • Vacuoles / metabolism

Substances

  • Intracellular Signaling Peptides and Proteins
  • ML-SA1 compound
  • Membrane Proteins
  • Phthalimides
  • Quinolines
  • VAC14 protein, human
  • Inositol

Supplementary concepts

  • Yunis Varon syndrome

Grants and funding