The Types and Symptoms of Facioscapulohumeral Muscular Dystrophy (FSHMD, FSHD, and FSH)

Introduction

Facioscapulohumeral muscular dystrophy is a form of muscular dystrophy that affects the muscles in the upper body. Facioscapulohumeral muscular dystrophy is also known as FSHD, Landouzy-Dejerine muscular dystrophy, and facioscapulohumeral disease. The National Institutes of Health (NIH) states that facioscapulohumeral muscular dystrophy is a genetic disorder that affects both men and women. Genetic screening is used to detect the disorder, with one test for facioscapulohumeral dystrophy, CK-MB, detecting the level of creatine kinase isoenzyme, which can vary in the different types of myopathy. The age of onset ranges from 10 to 26, but symptoms can appear later in life. Facioscapulohumeral muscular dystrophy is a rare disorder, affecting five out of 100,000 people, according to the NIH.

Types of Facioscapulohumeral Muscular Dystrophy

Two types of facioscapulohumeral muscular dystrophy exist; the difference between the two are the location of the gene mutation, but the symptoms are the same. The first type is facioscapulohumeral muscular dystrophy (FSHD1A), which is also known as chromosome 4 linked facioscapulohumeral muscular dystrophy. FSHD1A is the most common form of facioscapulohumeral muscular dystrophy, and is defined by the FSH Society as have a “deletion of 3.3-kb repeats from a chromosomal tandem repeat called D4Z4 located near the end of chromosome 4 at the 4q35-qter location.”

The second type is facioscapulohumeral muscular dystrophy (FSHD1B), which is also known as non-chromosome 4 linked facioscapulohumeral muscular dystrophy; FSHD1B is less prevalent compared to FSHD1A. The FSH Society notes that FSHD1B is caused by different genes than FSHD1A, though the mutated genes may be on chromosome 4 or another chromosome (the exact location has not been pinpointed).

Symptoms

The symptoms of facioscapulohumeral muscular dystrophy mainly affects the muscles in the upper arms, face, and shoulders, though some patients may have muscular problems in their lower legs, pelvis, and hips. The NIH notes that the symptoms begin mild, then grow progressively worse. Facial muscle weakness is common, causing decreased facial expressions and depressed or angry facial expression. Other facial symptoms include trouble pronouncing words, eyelid drooping, and an inability to whistle. Shoulder muscle weakness also results from facioscapulohumeral muscular dystrophy, with symptoms like scapular winging and sloping shoulders. The NIH adds that in advanced cases of facioscapulohumeral muscular dystrophy, lower leg weakness is possible, which can cause walking issues. Rarely, patients have hearing loss or abnormal heart rhythms.

Treatment and Quality of Life

The NIH states that no cure for facioscapulohumeral muscular dystrophy exists, though the disorder does not cause any additional disabilities. Recommended treatment is physical therapy to keep muscles strong; the NIH adds that inactivity can exacerbate symptoms. If symptoms are well managed, facioscapulohumeral muscular dystrophy should not cause a decrease in the patient’s quality of life or longevity.

References

MedlinePlus Medical Encyclopedia: Facioscapulohumeral Muscular Dystrophy (https://www.nlm.nih.gov/medlineplus/ency/article/000707.htm)

FSH Society: About FSHD (https://www.fshsociety.org/pages/about.html)