A novel mutation (K317M) in the MAPT gene causes FTDP and motor neuron disease

Neurology. 2005 May 10;64(9):1578-85. doi: 10.1212/01.WNL.0000160116.65034.12.


Background: Frontotemporal dementia with parkinsonism is often linked to chromosome 17 and is related to mutations in the MAPT gene. In some families the genetic basis is still unknown. The authors report two pedigrees with FTDP-17 harboring a novel mutation (K317M) in exon 11 in the MAPT gene.

Methods: The authors identified two apparently unrelated pedigrees with an autosomal dominant neurodegenerative condition. Thirteen patients were examined and eight autopsies were performed.

Results: Mean age at onset was 48 years. Mean disease duration was 6 years. Dysarthria often heralded the disease. All cases had parkinsonism and pyramidalism and half of them had amyotrophy. Behavioral or personality changes were not a prominent feature. Cognitive decline appeared late in the evolution. Neuropathologically, a massive degeneration of the substantia nigra without Lewy bodies was a constant finding. A variable degree of frontotemporal atrophy was found. Corticospinal tract degeneration and anterior horn neuron loss were present in six of seven autopsies in which the spinal cord was examined. An extensive deposition of abnormal tau protein in a mixed pattern (neuronal, glial) was observed. Pick's bodies were not seen. Biochemical analysis of tau revealed two bands of 64 and 68 kDa.

Conclusion: Genetic analysis revealed the same novel mutation (K317M) in exon 11 of the MAPT gene in both pedigrees. A common haplotype between members of the two pedigrees suggests that they belong to the same family.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Brain / metabolism
  • Brain / pathology
  • Brain / physiopathology
  • Chromosomes, Human, Pair 17 / genetics
  • DNA Mutational Analysis
  • Dementia / genetics*
  • Dementia / metabolism
  • Dementia / pathology
  • Female
  • Genes, Dominant
  • Genetic Markers / genetics
  • Genetic Predisposition to Disease / genetics
  • Genetic Testing
  • Genotype
  • Humans
  • Male
  • Middle Aged
  • Motor Neuron Disease / genetics*
  • Motor Neuron Disease / metabolism
  • Motor Neuron Disease / pathology
  • Motor Neurons / metabolism
  • Motor Neurons / pathology
  • Mutation / genetics*
  • Nerve Tissue Proteins / genetics*
  • Parkinsonian Disorders / genetics*
  • Parkinsonian Disorders / metabolism
  • Parkinsonian Disorders / pathology
  • Pedigree
  • Pyramidal Tracts / metabolism
  • Pyramidal Tracts / pathology
  • Pyramidal Tracts / physiopathology
  • Spinal Cord / metabolism
  • Spinal Cord / pathology
  • Spinal Cord / physiopathology
  • Substantia Nigra / metabolism
  • Substantia Nigra / pathology
  • Substantia Nigra / physiopathology
  • tau Proteins / genetics


  • Genetic Markers
  • MAPT protein, human
  • Nerve Tissue Proteins
  • tau Proteins