Dergiler / Sakarya Tıp Dergisi / 2026 / Volume: 16 Issue: 2

A Rare Metabolic Disorder: Two Siblings with a Pathogenic Variant in the PYGM Gene

Kübra Ateş(BURSA YÜKSEK IHTISAS TRAINING AND RESEARCH HOSPITAL, DEPARTMENT OF MEDICAL GENETICS)0000-0002-0669-8230
Dilcan Kotan(SAKARYA UNIVERSITY, SCHOOL OF MEDICINE)0000-0002-3101-4742
Levent Avcı(SAKARYA TRAINING AND RESEARCH HOSPITAL, DEPARTMENT OF NEUROLOGY)0009-0009-2798-8526
Sayfa
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Yayın Tarihi
2026-06-30
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⚡ TL;DR(1 Cümlede Hızlı Çıkarım)

This report underscores the clinical diversity of McArdle disease and emphasizes the value of family screening and molecular testing for early diagnosis and appropriate management.

📌 3 Maddede Bu Makale

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Amaç & Hipotez:McArdle disease (glycogen storage disease type V) is a rare autosomal recessive metabolic myopathy caused by pathogenic variants in the PYGM gene, leading to myophosphorylase deficiency.
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Temel Bulgular & Veri:The first case was a 38-year-old male with long-standing exercise-induced muscle pain, cramps, weakness, and a history of rhabdomyolysis.
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Sonuç & Katkı:This report underscores the clinical diversity of McArdle disease and emphasizes the value of family screening and molecular testing for early diagnosis and appropriate management.
🔬Tür:Case Report
📍Kapsam:Genişletilmiş Akademik Örneklem
⚙️Değişkenler:Glycogen storage disease type V · McArdle disease · Myophosphorylase

Abstract

McArdle disease (glycogen storage disease type V) is a rare autosomal recessive metabolic myopathy caused by pathogenic variants in the PYGM gene, leading to myophosphorylase deficiency. It typically presents with exercise intolerance, muscle pain, cramps, and, in some cases, rhabdomyolysis. Due to marked clinical heterogeneity, diagnosis is often delayed. We report two adult siblings with McArdle disease carrying the same homozygous PYGM variant and highlight the importance of family screening. Both siblings underwent detailed clinical, biochemical, and genetic evaluation. Laboratory investigations included creatine kinase levels, alanine aminotransferase, aspartate aminotransferase levels, and genetic analysis was performed using a next-generation sequencing panel targeting myopathy-related genes. The first case was a 38-year-old male with long-standing exercise-induced muscle pain, cramps, weakness, and a history of rhabdomyolysis. His creatine kinase level was 2,490 U/L, and physical examination revealed limb asymmetry, a high-arched palate, and kyphoscoliosis. The second case was his 26-year-old sister, who developed exercise-induced muscle pain at 20 years of age and had a markedly elevated creatine kinase level of 12,380 U/L. She showed a high-arched palate and atrophy of the left gastrocnemius muscle. Molecular analysis identified a homozygous PYGM c.1A>G (p.Met1Val) variant affecting the translation initiation codon in both siblings. Despite sharing the same pathogenic variant, the siblings exhibited notable intrafamilial phenotypic variability. This report underscores the clinical diversity of McArdle disease and emphasizes the value of family screening and molecular testing for early diagnosis and appropriate management.

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Bu Makaleye Atıf Yap

Ateş, K., Kotan, D., Avcı, L. (2026). A Rare Metabolic Disorder: Two Siblings with a Pathogenic Variant in the PYGM Gene. Sakarya Tıp Dergisi, Volume: 16 Issue: 2. https://doi.org/10.31832/smj.1777129

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Kaynakça (10)

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