What is the genetic abnormality found in myotonic dystrophy?
What is the genetic abnormality found in myotonic dystrophy?
DNA expansion in DMPK gene causes DM1 In DM1, the abnormal DNA expansion is in the DMPK (dystrophia myotonica protein kinase) gene on chromosome 19 q 13.3. The defect was identified in 1992 as the cause of DM1.
Is myotonic dystrophy a chromosomal disorder?
Myotonic Dystrophy is caused by a mutation on chromosome 19 so an affected individual will have one normal copy of chromosome 19 and one that carries the mutation. When the sex cells are produced (either sperm in males or eggs in females) they will only have one copy of each chromosome.
How is DM1 inherited?
DM1 is inherited in an autosomal dominant manner. Offspring of an affected individual have a 50% chance of inheriting the expanded allele.
What causes MMD?
Myotonic muscular dystrophy (MMD) is a multisystem disorder that affects the brain, skeletal and smooth muscles, eyes, heart, gastrointestinal tract, lungs, and endocrine system. The 2 forms, type 1 and type 2, are caused by different gene mutations.
Is myotonic dystrophy hereditary?
Both types of myotonic dystrophy are inherited in an autosomal dominant pattern , which means one copy of the altered gene in each cell is sufficient to cause the disorder. In most cases, an affected person has one parent with the condition.
How is myotonic dystrophy type 2 diagnosed?
Myotonic dystrophy is diagnosed by doing a physical exam. A physical exam can identify the typical pattern of muscle wasting and weakness and the presence of myotonia. A person with myotonic dystrophy may have a characteristic facial appearance of wasting and weakness of the jaw and neck muscles.
Is myotonic dystrophy recessive or dominant?
Can myotonic muscular dystrophy skip a generation?
A child is equally likely to have inherited the mutated gene from either parent. If both parents do not have the disease, their children cannot inherit it. Children with congenital myotonic dystrophy almost always inherit the disease from an affected mother.
What is Duchene?
Duchenne muscular dystrophy (DMD) is a genetic disorder characterized by progressive muscle degeneration and weakness due to the alterations of a protein called dystrophin that helps keep muscle cells intact. DMD is one of four conditions known as dystrophinopathies.
What causes myotonic dystrophy type 1 ( DM1 )?
DM1 is caused by expansion of a CTG triplet repeat in the 3′ non-coding region of DMPK, the gene encoding the DM protein kinase. More recently a second form of the disease, myotonic dystrophy type 2 (DM2) was recognized, which results from repeat expansion in a different gene.
How does myotonic dystrophy affect the endocrine system?
Endocrine System. Click here for a print-ready version of this page. In myotonic dystrophy patients, insulin-stimulated uptake of glucose is reduced due to insulin receptor deficiencies. To compensate for suppressed responsiveness (insulin resistance), insulin secretion may be increased.
How are laboratory tests used to diagnose myotonic dystrophy?
There are several laboratory tests that can be used to clarify the clinical diagnosis of myotonic dystrophy. One test, called electromyography (EMG), involves inserting a small needle into the muscle. The electrical activity of the muscle is studied and usually shows characteristic patterns of myotonic dystrophy. [3]
What are the symptoms of congenital myotonic dystrophy?
Symptoms of congenital myotonic dystrophy are present from birth and include weakness of all muscles, breathing problems, clubfeet, developmental delays and intellectual disabilities. [1] [4] Do you have updated information on this disease? We want to hear from you.
