MLIP-Related Myopathy: Two Unreported Pathogenic Variants - A Case Report

Area of Science:

• Genetics
• Neurology
• Rare Diseases

Background:

• Myopathy with myalgia, increased serum levels of creatine kinase, and with or without episodic rhabdomyolysis-1 (MMCKR1) is a rare MLIP-related myopathy.
• Characterized by muscle cramps, stiffness, cardiac involvement, and elevated creatine kinase (CK) levels.
• Approximately 15 cases have been reported globally.

Purpose of the Study:

• To describe two novel cases of MLIP-related myopathy in Mexican patients.
• To identify and characterize new genetic variants in the MLIP gene.
• To compare clinical findings with previously reported cases.

Main Methods:

• Genetic analysis of MLIP gene in two patients.
• Clinical assessment including neurological examination and symptom description.
• Comparison of patient findings with existing literature.

Main Results:

• Two previously unreported MLIP variants were identified: c.645+2T>C and c.1905_1912del.
• Predominant symptoms included muscle stiffness upon exertion (walking/running).
• Absence of myalgia, cramps, or rhabdomyolysis was noted; case 1 exhibited unique joint, neurological, and behavioral findings.

Conclusions:

• This study reports the first two Mexican cases of MLIP-related myopathy.
• New MLIP variants expand the known mutation spectrum for this myopathy.
• The identified clinical features, including novel findings in case 1, broaden the understanding of MLIP-related myopathy's phenotypic variability.