About

Nemaline myopathy is a rare congenital disease which affects the skeletal muscle.

It is characterised by weakness in the muscle, hypotonia, and nemaline rods in muscle fibres.

Clinical Subtypes

There are six subtypes of this disease based on severity and age of onset of the disease. There are

Severe congenital which is usually lethal in infancy, 

Intermediate, 

Typical, 

Mild childhood-onset, 

Mild adult-onset, and 

The other forms e.g., Amish type.

Common Form

The most prevalent form is typical congenital nemaline myopathy.

It allows individuals to walk and lead active lives.

Inheritance Pattern

Its inheritance pattern is variable, depending on the specific genetic mutation responsible for the disease condition.

Symptoms

Its symptoms include:

Muscle weakness

Hypotonia which is diminished muscle tone

Reduced or absence of reflexes

Weakness in breathing and swallowing the muscles, 

This leads to increased morbidity and mortality.

Pathology

This disease results from a disruption in myofibril in muscle, which is a contractile structure within a muscle fibre responsible for muscle contraction.

Associated Conditions

Some patients also show monoclonal gammopathy.

Monoclonal gammopathies are conditions in which abnormal proteins or antibodies are found in the blood. These proteins are made up of a small number of plasma cells in the bone marrow.

Treatment 

There is no definitive cure for this disease.

Some corticosteroids may be beneficial in some cases. 

There have also been reports of successful treatments with intravenous immunoglobulin (IVIG). However, these treatment methods are not clinically proven.

Most Affected Muscles

The Disease mainly affects neck flexors and respiratory muscles, leading to generalised weakness and delayed motor milestones.

Diagnosis

It is diagnosed based on clinical symptoms.

Muscle biopsy for nemaline rods and genetic testing to identify specific mutations are done.

PRACTICE QUESTION

Q.Consider the following statements about the “Nemaline myopathy” recently seen in the news: 

1. It is a rare congenital disease which affects the skeletal muscle.
2. In this condition, Hypotonia is seen in the diseased person.
3. There are various drugs available for the treatment of this disease.

How many of the above statements is/are correct?

A.Only one

B.Only two

C. All Three

D.None

Answer: B

Explanation:

Statement 1 is correct: 

Nemaline myopathy is a rare congenital disease which affects the skeletal muscle.

It is characterised by the weakness in muscle, hypotonia, and nemaline rods in muscle fibers.

There are six subtypes of this disease based on severity and age of onset of the disease. There are

Severe congenital which is usually lethal in infancy, 

Intermediate, 

Typical, 

Mild childhood-onset, 

Mild adult-onset, and 

The other forms e.g., Amish type.

Statement 2 is correct: 

Its symptoms includes:

Muscle weakness

Hypotonia which is diminished muscle tone

Reduced or absence of reflexes

Weakness in breathing and swallowing the muscles, which leads to increased morbidity and mortality.

Statement 3 is incorrect: 

There is no definitive cure for this disease.

Some corticosteroids may be beneficial in some cases. 

There have also been reports of successful treatments with intravenous immunoglobulin (IVIG). However these treatment methods are not clinically proven.