What are the other Names for this Condition? (Also known as/Synonyms)

• Distal Myopathy Type 1
• Laing Early-Onset Distal Myopathy

What is Laing Distal Myopathy? (Definition/Background Information)

• Laing Distal Myopathy is a slowly progressive muscle disorder that tends to begin in childhood. Early symptoms include weakness in the feet and ankles, followed by weakness in the hands and wrists
• Weakness in the feet leads to tightening of the Achilles tendon, an inability to lift the big toe, and a high-stepping walk
• Weakness in the hands makes it more difficult to lift the fingers, especially the third and fourth fingers
• As the muscle weakness slowly progresses over the course of many years, other muscles of the body (e.g., neck, face, legs, hips, and shoulders) weaken
• Most affected people remain mobile throughout life. Life expectancy is normal
• Laing Distal Myopathy is caused by mutations in the MYH7 gene and is inherited in an autosomal dominant fashion

(Source: Laing Distal Myopathy; Genetic and Rare Diseases Information Center (GARD) of National Center for Advancing Translational Sciences (NCATS), USA.)

Who gets Laing Distal Myopathy? (Age and Sex Distribution)

• Laing Distal Myopathy is a rare congenital disorder whose prevalence is not known
• The manifestation of symptoms can occur any time before the early 20s. However, in most cases, the presentation of symptoms occurs in childhood
• Both males and females may be affected
• Worldwide, individuals of all racial and ethnic groups may be affected

What are the Risk Factors for Laing Distal Myopathy? (Predisposing Factors)

• A positive family history may be an important risk factor, since Laing Distal Myopathy is an inherited condition
• Currently, no other risk factors have been clearly identified for Laing Distal Myopathy

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Laing Distal Myopathy? (Etiology)

• Laing Distal Myopathy is caused by mutation(s) on the MYH7 gene
• This gene codes for a protein known as the myosin heavy chain of type 1 of skeletal and cardiac ventricular muscle fibers
• The condition is inherited in an autosomal dominant manner

Autosomal dominant inheritance: Autosomal dominant conditions are traits or disorders that are present when only one copy of the mutation is inherited on a non-sex chromosome. In these types of conditions, the individual has one normal copy and one mutant copy of the gene. The abnormal gene dominates, masking the effects of the correctly function gene. If an individual has an autosomal dominant condition, the chance of passing the abnormal gene on to their offspring is 50%. Children, who do not inherit the abnormal gene, will not develop the condition or pass it on to their offspring.

What are the Signs and Symptoms of Laing Distal Myopathy?

The signs and symptoms of Laing Distal Myopathy may include:

• Amyotrophy of ankle musculature 
• Childhood onset 
• Distal muscle weakness
• Elevated serum creatine phosphokinase
• EMG: neuropathic changes
• Facial palsy
• Gait disturbance
• High palate
• Infantile onset
• Mildly elevated creatine phosphokinase 
• Myalgia 
• Neck muscle weakness
• Pes cavus 
• Phenotypic variability 
• Ragged-red muscle fibers 
• Scoliosis 
• Slow progression 
• Toe extensor amyotrophy 
• Type 1 muscle fiber predominance 
• Weakness of long finger extensor muscles

Based on the frequency of symptoms observed, the following information may be noted:

Occasionally present symptoms in 5-29% of the cases:

• Dilated cardiomyopathy 
• Proximal muscle weakness

(Source: Laing Distal Myopathy; Orphanet, National Institute of Health and Medical Research (INSERM), Paris.)

How is Laing Distal Myopathy it Diagnosed?

Laing Distal Myopathy is diagnosed on the basis of the following information:

• Complete physical examination
• Thorough medical history evaluation
• Assessment of signs and symptoms
• Laboratory tests
• Imaging studies
• Biopsy studies, if necessary
• Molecular genetic testing to check for or confirm causative gene mutation(s)

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Laing Distal Myopathy?

The complications of Laing Distal Myopathy may include:

• Problems with movement due to muscle weakness
• Abnormal heart function due to cardiomyopathy

Complications may occur with or without treatment, and in some cases, due to treatment also.

How is Laing Distal Myopathy Treated?

There is no cure for Laing Distal Myopathy, since it is a genetic condition. The treatment is usually given to manage the signs and symptoms and any complication that develops.

How can Laing Distal Myopathy be Prevented?

Currently, Laing Distal Myopathy may not be preventable, since it is a genetic disorder.

• Genetic testing of the expecting parents (and related family members) and prenatal diagnosis (molecular testing of the fetus during pregnancy) may help in understanding the risks better during pregnancy
• If there is a family history of the condition, then genetic counseling will help assess risks, before planning for a child
• Active research is currently being performed to explore the possibilities for treatment and prevention of inherited and acquired genetic disorders

Regular medical screening at periodic intervals with tests and physical examinations are recommended.

What is the Prognosis of Laing Distal Myopathy? (Outcomes/Resolutions)

• The prognosis of Laing Distal Myopathy is dependent upon the severity of the signs and symptoms and associated complications, if any
• The condition is slowly progressive, although is not reported to affect one’s lifespan

Additional and Relevant Useful Information for Laing Distal Myopathy:

The following DoveMed website link is a useful resource for additional information:

http://www.dovemed.com/diseases-conditions/rare-disorders/