Myotonic dystrophy
An inherited disease in which the muscles contract but have decreasing power to relax — this phenomenon is termed myotonia (irritability and prolonged contraction of muscles). The disease also leads to a mask-like expressionless face, premature balding, cataracts, and heart arrhythmias (abnormalities in heart rhythm). The onset of such problems is usually in young adulthood. However, onset can be at any age and the disease is extremely variable in the degree of severity. Myotonic dystrophy is due to a trinucleotide repeat (a "stuttering" sequence of three bases) in the DNA. The myotonic dystrophy gene (called DM1), found on chromosome 19q13.3, codes for a protein kinase (an enzyme) that is found in skeletal muscle. An unusual feature is that the signs and symptoms of the disease usually become more severe with each successive generation. This is because mistakes in the faithful copying of the gene from one generation to the next result in the amplification of a genomic "AGC/CTG triplet repeat." Unaffected individuals have between 5 and 27 copies of AGC/CTG, myotonic dystrophy patients who are minimally affected have at least 50 repeats, while more severely affected patients have an expansion of up to several kilobase pairs. Myotonic dystrophy is not one genetic entity. Some families with myotonic dystrophy have a mutation in a gene on chromosome 3q21 (at the DM2 locus). The DM2 mutation is a huge expansion of a tetranucleotide repeat (CCTG) in a noncoding region of the ZNF9 gene. Both DM1 and DM2 appear to cause disease through the effects of the mutant RNA (that contains abnormal repeating sequences). Myotonic dystrophy is not to be confused with muscular dystrophy. They are distinct and different diseases.

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myotonic dystrophy n an inherited condition that is characterized by delay in the ability to relax muscles after forceful contraction, wasting of muscles, formation of cataracts, premature baldness, atrophy of the gonads, endocrine and cardiac abnormalities, and often mental retardation and that is inherited as an autosomal dominant trait abbr. DM called also Steinert's disease

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a rare, slowly progressive, hereditary disease characterized by myotonia followed by atrophy of the muscles (especially those of the face and neck), cataracts, hypogonadism, frontal balding, and cardiac abnormalities. Called also dystrophia myotonica, myotonia atrophica, and Steinert disease.

Medical dictionary. 2011.

Look at other dictionaries:

  • Myotonic dystrophy — Classification and external resources ICD 10 G71.1 OMIM 160900 602668 …   Wikipedia

  • myotonic dystrophy — noun a severe form of muscular dystrophy marked by generalized weakness and muscular wasting that affects the face and feet and hands and neck; difficult speech and difficulty with the hands that spreads to the arms and shoulders and legs and… …   Useful english dictionary

  • myotonic dystrophy — noun Medicine a form of muscular dystrophy accompanied by myotonia …   English new terms dictionary

  • myotonic dystrophy — noun Date: 1963 a muscular disorder that is characterized by dystrophic muscle weakness and myotonia affecting multiple bodily systems and that is caused by an abnormally high number of repeats of a codon in the genetic material …   New Collegiate Dictionary

  • myotonic dystrophy — An inherited human neuromuscular disease classed as an autosomal dominant disease in which there is progressive muscle weakening and wasting. Caused by an unstable nucleotide repeat (CTG) in the 3 untranslated region …   Dictionary of molecular biology

  • myotonic dystrophy — dystrophia myotonica …   The new mediacal dictionary

  • Myotonic dystrophy protein kinase — Dystrophia myotonica protein kinase, also known as DMPK, is a human gene. PBB Summary section title = summary text = The protein encoded by this gene is a serine threonine kinase that is closely related to other kinases that interact with members …   Wikipedia

  • Myotonic Dystrophy Foundation — The Myotonic Dystrophy Foundation (MDF) is a non profit, 501 (c) (3) organization founded by families living with myotonic dystrophy (DM). Through education, advocacy and research, MDF is committed to establishing a voice and a face for this… …   Wikipedia

  • Дистрофия Миотоническая (Dystrophia Myotonica, Myotonic Dystrophy) — разновидность мышечной дистрофии, при которой имеют место мышечная слабость и атрофия мышц, сопровождающиеся неестественным удлинением мышечных сокращений после каждого произвольного движения (см. Миотония). Мышцы лица, височные и шейные мышцы… …   Медицинские термины

  • myotonic muscular dystrophy — n MYOTONIC DYSTROPHY …   Medical dictionary

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