Myophosphorylase deficiency (McArdle's disease) in two interrelated families

Area of Science:

• Biochemistry
• Genetics
• Clinical Medicine

Background:

• Myophosphorylase deficiency, also known as McArdle disease, is a glycogen storage disease affecting muscle energy metabolism.
• It is characterized by exercise-induced muscle pain, cramping, and fatigue due to impaired glycogen breakdown.

Purpose of the Study:

• To investigate the clinical and laboratory findings of patients with myophosphorylase deficiency.
• To analyze the genetic inheritance pattern within two interrelated families.
• To explore the possibility of a sex-limited mode of inheritance.

Main Methods:

• Clinical examination of affected patients and unaffected relatives.
• Laboratory investigations to assess muscle function and enzyme activity.
• Genetic analysis to determine the mode of inheritance.

Main Results:

• Three patients (two sisters and a male cousin) presented with characteristic features of myophosphorylase deficiency.
• Nine unaffected relatives were investigated, showing no clear evidence of a heterozygous state.
• Genetic findings strongly supported an autosomal recessive inheritance pattern.

Conclusions:

• Myophosphorylase deficiency is confirmed as a rare autosomal recessive disorder.
• The study discusses a potential sex-limited mode of inheritance, warranting further investigation.
• Understanding the genetic basis is crucial for diagnosis and genetic counseling.