Limb-girdle muscular dystrophy type 1B

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Other Names:

LGMD1B; Muscular dystrophy, proximal, type 1B

Categories:

Congenital and Genetic Diseases; Heart Diseases; Nervous System Diseases

This disease is grouped under:

Limb-girdle muscular dystrophy

Summary Summary

Limb-girdle muscular dystrophy type 1B (LGMD1B) is one of many types of limb-girdle muscular dystrophy. These diseases affect the voluntary muscles, which are the muscles that are moved on purpose, such as the arms, legs, fingers, toes, and facial muscles. Specifically, LGMD1B causes muscle weakness in the lower limbs. The muscle weakness typically affects the muscles closest to the center of the body (proximal muscles) such as the upper legs. The disease is progressive, leading to a loss of muscle strength and bulk over a number of years.^[1]

Limb-girdle muscular dystrophy type 1B is caused by mutations (changes) to the LMNA gene. The disease is inherited in an autosomal dominant manner. A diagnosis of LGMD1B is suspected in people who have signs and symptoms consistent with the disease, and the diagnosis can be confirmed with laboratory tests. While there are not treatments that can reverse the muscle weakness associated with the disease, supportive treatment can decrease the complications.^[1]

Last updated: 12/19/2017

Symptoms Symptoms

Limb-girdle muscular dystrophy type 1B (LGMD1B) causes muscle weakness, especially in the lower limbs. The muscle weakness typically affects the muscles closest to the center of the body (proximal muscles) such as the upper legs. The muscle weakness can cause an unusual walking gait and difficulty running or using the stairs. The disease is progressive, leading to a loss of muscle strength and bulk over a number of years.^[1]^[2] Later in adulthood, the muscles of the upper body may also become affected.^[3]

The symptoms of LGMD1B can begin at any time between childhood and adulthood. About half of all affected individuals show signs of the disease in childhood. Other symptoms of the disease may include difficulty straightening the elbows (elbow contracture) and heart problems including arrhythmia or left ventricular hypertrophy. The signs and symptoms of people with LGMD1B can vary, even among members of the same family.^[1]

Last updated: 12/19/2017

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Cause Cause

Limb-girdle muscular dystrophy type 1B is caused by mutations (changes) to the LMNA gene. The LMNA gene provides instructions to the body to make a protein that is responsible for providing stability and strength to the cells. Specifically, LMNA provides instructions to make a protein that is located in the nuclear envelope, which surrounds the nucleus. The proteins of the nuclear envelope help move molecules in and out of the nucleus. When there are changes to the LMNA gene, this protein is not made correctly. It is not clear exactly why changes in this gene cause the signs and symptoms associated with LGMD1B, but it is thought that the protein created by the LMNA gene may be important for controlling the expression of other genes.^[4]

Last updated: 12/19/2017

Inheritance Inheritance

Limb-girdle muscular dystrophy type 1B (LGMD1B) is inherited in an autosomal dominant manner.^[1] This means that only one copy of the LMNA gene has a change (mutation) in people who are affected with the disease. We inherit one copy of each gene from our mother and one from our father. If a person with LGMD1B goes on to have children, for each child there is a 50% chance that he or she will have LGMD1B as well.

Some people with LGMD1B do not have a family history of the disease. This could happen for a couple of reasons. First, it could be that there are other family members with the disease, but they do not know it because they have never been diagnosed. The symptoms of LGMD1B exhibit variable expressivity. This means that people with the disease can have many different signs and symptoms, even within the same family. For example, some people with LGMD1B may have heart problems but no other signs of muscle weakness.^[3] Therefore, it can sometimes be difficult to see a history of LGMD1B in the family of an affected individual.

In some cases, the reason that there is no family history of LGMD1B is because the affected individual is the first person in the family to have a genetic change in LMNA.^[1] In these cases, the genetic change is de novo. This means the genetic change happened for the first time in the family in the person who has symptoms of the disease, and other family members do not have LGMD1B. However, the affected individual still has a 50% chance to pass on the genetic change in LMNA to each of his or her children.

Last updated: 12/19/2017

Diagnosis Diagnosis

Limb-girdle muscular dystrophy type 1B (LGMD1B) is typically suspected when a person has signs or symptoms consistent with the disease. The doctor may wish to take a thorough personal and family history and to run some laboratory tests. These tests may include:^[1]

Electromyography (EMG)
Creatine-kinase levels
Muscle biopsy
Imaging of the heart, such as an echocardiogram

In some cases, genetic testing of genes associated with muscular dystrophies may be ordered to confirm the diagnosis.^[1]

Last updated: 12/19/2017

Testing Resources

The Genetic Testing Registry (GTR) provides information about the genetic tests for this condition. The intended audience for the GTR is health care providers and researchers. Patients and consumers with specific questions about a genetic test should contact a health care provider or a genetics professional.

Treatment Treatment

Unfortunately, there is no cure for limb-girdle muscular dystrophy type 1B (LGMD1B). Treatment options that may be recommended for people with LGMD1B may include:^[1]

Weight control to avoid obesity
Physical therapy and stretching exercises to prevent contractures of the elbows
Use of mechanical aids such as canes, walkers, and wheelchairs
Monitoring for evidence of heart problems

In some cases, a pacemaker may be necessary to treat heart problems associated with LGMD1B. It is recommended that people with LGMD1B be provided with social and emotional support to cope with the diagnosis. Other specialists that may be recommended include a neurologist, cardiologist, occupational therapist, nutritionist, and genetic counselor.^[1]

Last updated: 12/19/2017

Prognosis Prognosis

The long-term outlook for people affected by limb-girdle muscular dystrophy type 1B depends on the signs and symptoms present in each person. In general, LGMD1B is a progressive disease, meaning the muscle weakness can continue to worsen. If the heart problems associated with the disease are not monitored and treated, people with LGMD1B are at risk to have a sudden heart problem that can cause death.^[1] Some people with LGMD1B have successfully received heart transplants.^[5]

Last updated: 12/19/2017

Find a Specialist Find a Specialist

If you need medical advice, you can look for doctors or other healthcare professionals who have experience with this disease. You may find these specialists through advocacy organizations, clinical trials, or articles published in medical journals. You may also want to contact a university or tertiary medical center in your area, because these centers tend to see more complex cases and have the latest technology and treatments.

If you can’t find a specialist in your local area, try contacting national or international specialists. They may be able to refer you to someone they know through conferences or research efforts. Some specialists may be willing to consult with you or your local doctors over the phone or by email if you can't travel to them for care.

You can find more tips in our guide, How to Find a Disease Specialist. We also encourage you to explore the rest of this page to find resources that can help you find specialists.

Healthcare Resources

To find a medical professional who specializes in genetics, you can ask your doctor for a referral or you can search for one yourself. Online directories are provided by the American College of Medical Genetics and the National Society of Genetic Counselors. If you need additional help, contact a GARD Information Specialist. You can also learn more about genetic consultations from Genetics Home Reference.

Research Research

Research helps us better understand diseases and can lead to advances in diagnosis and treatment. This section provides resources to help you learn about medical research and ways to get involved.

Clinical Research Resources

ClinicalTrials.gov lists trials that are related to Limb-girdle muscular dystrophy type 1B. Click on the link to go to ClinicalTrials.gov to read descriptions of these studies.

Please note: Studies listed on the ClinicalTrials.gov website are listed for informational purposes only; being listed does not reflect an endorsement by GARD or the NIH. We strongly recommend that you talk with a trusted healthcare provider before choosing to participate in any clinical study.

Organizations Organizations

Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.

Organizations Supporting this Disease

Cure CMD - Congenital Muscular Dystrophy
19401 S. Vermont Ave., Suite J100
Torrance, CA 90502
Telephone: 323-250-2399 or 424-265-0874
E-mail: info@curecmd.org
Website: https://www.curecmd.org/
Muscular Dystrophy Association (MDA)
222 S Riverside Plaza
Suite 1500
Chicago, IL 60606
Toll-free: 1-833-275-6321 (Helpline)
E-mail: resourcecenter@mdausa.org
Website: https://www.mda.org
Muscular Dystrophy Family Foundation
P.O. Box 776
Carmel, IN 46082
Telephone: +1-317-615-9140
E-mail: info@mdff.org
Website: https://mdff.org/
MDFF provides financial assistance, quality programs and services for the Muscular Dystrophy community in Indiana.
Muscular Dystrophy UK
61A Great Suffolk Street
London, SE1 0BU United Kingdom
Toll-free: 0800 652 6352 (Helpline)
Telephone: (+44) 0 020 7803 4800
E-mail: info@musculardystrophyuk.org
Website: https://www.musculardystrophyuk.org/

Social Networking Websites

Living with Limb-Girdle Muscular Dystrophy
Website: https://www.facebook.com/groups/Living.with.LGMD/

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Learn More Learn More

These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

Where to Start

Genetics Home Reference (GHR) contains information on Limb-girdle muscular dystrophy type 1B. This website is maintained by the National Library of Medicine.

In-Depth Information

GeneReviews provides current, expert-authored, peer-reviewed, full-text articles describing the application of genetic testing to the diagnosis, management, and genetic counseling of patients with specific inherited conditions.
The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
Online Mendelian Inheritance in Man (OMIM) is a catalog of human genes and genetic disorders. Each entry has a summary of related medical articles. It is meant for health care professionals and researchers. OMIM is maintained by Johns Hopkins University School of Medicine.
Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.
PubMed is a searchable database of medical literature and lists journal articles that discuss Limb-girdle muscular dystrophy type 1B. Click on the link to view a sample search on this topic.

GARD Answers GARD Answers

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Have a question? Contact a GARD Information Specialist.

References References

Pegoraro E and Hoffman EP. Limb-Girdle Muscular Dystrophy Overview. GeneReviews. August 30, 2012; http://www.ncbi.nlm.nih.gov/books/NBK1408/.
Limb-girdle muscular dystrophy. Genetics Home Reference (GHR). December 2014; http://ghr.nlm.nih.gov/condition/limb-girdle-muscular-dystrophy.
Muscular Dystrophy; Limb-Girdle, Type 1B; LGMD1B. Online Mendelian Inheritance in Man. March 27, 2017; https://www.omim.org/entry/159001.
LMNA gene. Genetics Home Reference (GHR). June 2017; http://ghr.nlm.nih.gov/gene/LMNA.
Ambrosi P, Mouly-Bandini A, Attarian S, and Habib G. Heart transplantation in 7 patients from a single family with limb-girdle muscular dystrophy caused by lamin A/C mutation. International Journal of Cardiology. November 12, 2009; 137(3):e75-76. https://www.ncbi.nlm.nih.gov/pubmed/19446900.