Mitochondrial DNA mutation at np 3243 in a family with maternally inherited diabetes mellitus

Acta Diabetol. 1999 Sep;36(3):163-7. doi: 10.1007/s005920050161.


Mitochondrial DNA (mtDNA) gene defects may play a role in the development of maternally inherited diabetes mellitus and deafness (MIDD). A family from Southern Italy who showed maternal transmission of type 2 diabetes mellitus with three individuals affected is described. A 10.4 kb deletion and mutations at nucleotide positions (np) 3243, 7445 and 11778 in the mtDNA of six relatives were sought. The mitochondrial np 3243 mutation of the tRNA Leu (UUR) gene was identified in a boy affected by optic atrophy and mental retardation, as well as in his diabetic mother. No other mutations or deletions were found. Our study points out the variable phenotypic expression of the np 3243 mtDNA mutation. This may suggest the presence of other mitochondrial or nuclear mutations required to modulate the phenotype. A clinical and metabolic follow-up of all family members was necessary to understand the role of the np 3243 mutation, especially in one child affected by optic atrophy and mental retardation. Further studies will be aimed at investigating the prevalence of mutations and deletions of mtDNA in type 2 diabetes mellitus.

Publication types

  • Case Reports

MeSH terms

  • Blood Glucose / metabolism
  • DNA, Mitochondrial / genetics*
  • Diabetes Mellitus, Type 2 / genetics*
  • Diabetes Mellitus, Type 2 / pathology
  • Extrachromosomal Inheritance / genetics*
  • Female
  • Glucose Tolerance Test
  • Hearing Loss, Sensorineural / genetics
  • Hearing Loss, Sensorineural / pathology
  • Humans
  • Male
  • Mothers
  • Optic Atrophies, Hereditary / genetics
  • Optic Atrophies, Hereditary / pathology
  • Pedigree
  • Point Mutation


  • Blood Glucose
  • DNA, Mitochondrial