Using PacBio SMRT Sequencing in Myotonic Dystrophy Type 1 and Other Rare Disorders


Stéphanie Tomé is an investigator at the Sorbonne Université in Paris, France. A recent article in PacBio describes Tomé’s research into a disease that becomes progressively worse with each generation.

The wide range of symptoms in myotonic dystrophy type 1 (MD1) patients makes it difficult for genetic counselors to predict the severity of the patients’ disease.

About Myotonic Dystrophy Type 1 (MD1)

There are two types of autosomal inherited (from parents) myotonic dystrophy. Generally, the central nervous system, endocrine system, and muscles, as well as the heart and eyes, are affected. Of the two types, MD1 is more severe.

MD1 has three forms that share similarities. The forms are categorized as mild, classic and congenital (at birth). A normal life span is only associated with the mild form of the disease.

Patients with the classic form of MD1 will eventually become disabled as they will experience many of the aforementioned symptoms. These patients will typically have a shortened life span.

Infants with the congenital form of MD1 are in a weakened condition at birth often resulting in fatal breathing complications.

Treatment of each form of the disease is administered in accordance with the patient’s symptoms.

Tomé believes in spending some time out of the lab speaking to patients. She hopes to bring about a better quality of life for them and to eventually make positive changes in their disease. Tomé understands how anxious most patients are about their disease and what lies ahead for their children.

About PacBio SMRT Sequencing

In order to accomplish these goals, Tomé is utilizing a system called PacBio SMRT Sequencing (SMRT).

Together with ten other scientists on her research team, plus collaborators worldwide, Tomé will be working with DM1 patient’s mutated genes in an effort to establish the pattern and size of CTG repeats.

SMRT will enable the scientists to capture sequences in DM1 patients as well as in other expansion disorders such as in fragile X syndrome and Huntington’s disease. There is a behavioral similarity among triplet diseases. Tomé hopes that findings from the MD1 project might be useful in treating as many as thirteen other similar disorders.

About Myotonic Dystrophy Protein Kinase

The DMPK gene issues instructions for the creation of the myotonic dystrophy protein kinase which inhibits the myosin phosphatase enzyme. This enzyme is involved with relaxation and muscle contraction associated with MD1 symptoms.

About the DMPK Gene Triple Repeats

DM1 is the result of an expansion of CTG trinucleotide repeats in the DMPK gene. (CTG is an acronym for cytosine-thymine-guanine triplet repeat.) Scientists have found that the expansion of these repeats can cause neuromuscular and neurological diseases.

The actual function of the DMPK gene is not yet known but all evidence points to DMPK playing an important role in heart, muscle and brain cells.

Symptoms in children may include respiratory and cardiac abnormalities as well as intellectual impairment. In addition to muscle weakness, adults with advanced disease may experience respiratory complications. Early onset of the disease generally results in more severe symptoms.

At The End of The Day

Tomé does not have high expectations that data from the MD1 project will bring about an immediate solution. However, there is every indication that the project will offer insight into the disorder.

There is also the distinct possibility that SMRT Sequencing will become a standard method for molecular diagnostics and lead to better-informed patients.


Rose Duesterwald

Rose Duesterwald

Rose became acquainted with Patient Worthy after her husband was diagnosed with Acute Myeloid Leukemia (AML) six years ago. During this period of partial remission, Rose researched investigational drugs to be prepared in the event of a relapse. Her husband died February 12, 2021 with a rare and unexplained occurrence of liver cancer possibly unrelated to AML.

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