Skip to
  1. Homepage
  2. Rare diseases
  3. Search
Simple search

Simple search

(*) mandatory field


Other search option(s)

Tibial muscular dystrophy

Synonym(s) Distal myopathy, Udd type
Distal titinopathy
Finnish tibial muscular dystrophy
Udd myopathy
Prevalence 1-9 / 100 000
Inheritance Autosomal dominant
or Autosomal recessive
Age of onset Adult
  • G71.0
  • C1838244
  • C536815
MedDRA -


Disease definition

Tibial muscular dystrophy (TMD) is a distal myopathy characterized by weakness of the muscles of the anterior compartment of lower limbs, appearing in the fourth to seventh decade of life.


TMD is highly prevalent in Finland (1/5,000) due to a founder mutation, making it the most common muscle disease in Finland. The disease has also rarely been identified in families in several other European countries.

Clinical description

TMD manifests after the age of 35 to 40 (rarely after the age of 60) as slowly progressive weakness and atrophy of the anterior tibial muscles with decreased dorsiflexion. Muscle involvement may remain asymmetrical for many years. After about 10 to 20 years, long toe extensors become involved causing foot drop, tripping and clumsiness while walking. Proximal limb muscles, mainly hamstring muscles, may be involved after the age of 60 to 70 and may necessitate the use of a cane and reduced walking distances. Extensor digitorum brevis muscles are spared and involvement of upper limbs is very rare. Neither cardiomyopathy nor respiratory failure has been encountered. TMD may present in a mild form (may remain unnoticed even in elderly individuals) or as aberrant phenotypic forms in about 9% of cases (proximal leg or posterior lower leg muscle involvement even at onset).


TMD is linked to mutations in the TTN gene (2q31) encoding the protein Titin. The Finnish founder mutation (FINmaj) is located in the last exon 363(Mex6). Atypical presentations in Finnish patients have recently been explained by modifying second mutations in TTN. Seven other mutations of the TTN gene causing TMD have been identified in non-Finnish populations of which some C-terminal titin mutations can be recessive, manifesting the disease in homozygosity or in compound heterozygosity (usually with recessive truncating titin mutations). FINmaj mutation in homozygosity or in combination with truncating recessive titin mutations causes early onset autosomal recessive limb girdle muscular dystrophy (LGMD2J, see this term).

Genetic counseling

Mode of inheritance of typical TMD is autosomal dominant, with a 50% risk of transmission to offspring, while some forms of TMD may be autosomal recessive.

Expert reviewer(s)

  • Dr Johanna PALMIO
  • Pr Bjarne UDD

(*) Required fields.

Attention: Only comments seeking to improve the quality and accuracy of information on the Orphanet website are accepted. For all other comments, please send your remarks via contact us. Only comments written in English can be processed.

Captcha image

Detailed information

Summary information
Clinical genetics review
Get Acrobat Reader
The documents contained in this web site are presented for information purposes only. The material is in no way intended to replace professional medical care by a qualified specialist and should not be used as a basis for diagnosis or treatment.