Mutations in the SPTLC2 subunit of serine palmitoyltransferase cause hereditary sensory and autonomic neuropathy type I

Am J Hum Genet. 2010 Oct 8;87(4):513-22. doi: 10.1016/j.ajhg.2010.09.010.

Abstract

Hereditary sensory and autonomic neuropathy type I (HSAN-I) is an axonal peripheral neuropathy associated with progressive distal sensory loss and severe ulcerations. Mutations in the first subunit of the enzyme serine palmitoyltransferase (SPT) have been associated with HSAN-I. The SPT enzyme catalyzes the first and rate-limiting step in the de novo sphingolipid synthesis pathway. However, different studies suggest the implication of other genes in the pathology of HSAN-I. Therefore, we screened the two other known subunits of SPT, SPTLC2 and SPTLC3, in a cohort of 78 HSAN patients. No mutations were found in SPTLC3, but we identified three heterozygous missense mutations in the SPTLC2 subunit of SPT in four families presenting with a typical HSAN-I phenotype. We demonstrate that these mutations result in a partial to complete loss of SPT activity in vitro and in vivo. Moreover, they cause the accumulation of the atypical and neurotoxic sphingoid metabolite 1-deoxy-sphinganine. Our findings extend the genetic heterogeneity in HSAN-I and enlarge the group of HSAN neuropathies associated with SPT defects. We further show that HSAN-I is consistently associated with an increased formation of the neurotoxic 1-deoxysphinganine, suggesting a common pathomechanism for HSAN-I.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Base Sequence
  • Cell Line
  • Cloning, Molecular
  • Cohort Studies
  • DNA Mutational Analysis
  • DNA Primers / genetics
  • Genetic Complementation Test
  • Hereditary Sensory and Autonomic Neuropathies / genetics*
  • Humans
  • Microsatellite Repeats / genetics
  • Molecular Sequence Data
  • Mutation, Missense / genetics
  • Serine C-Palmitoyltransferase / genetics*
  • Serine C-Palmitoyltransferase / metabolism

Substances

  • DNA Primers
  • SPTLC2 protein, human
  • Serine C-Palmitoyltransferase

Associated data

  • RefSeq/NM_001180370
  • RefSeq/NM_004863
  • RefSeq/NM_018327