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GTR Home > Tests > Duchenne and Becker muscular dystrophy (DMD gene)

Indication

This is a clinical test intended for Help: Diagnosis, Mutation Confirmation

Clinical summary

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Imported from GeneReviews

The dystrophinopathies cover a spectrum of X-linked muscle disease ranging from mild to severe that includes Duchenne muscular dystrophy, Becker muscular dystrophy, and DMD-associated dilated cardiomyopathy (DCM). The mild end of the spectrum includes the phenotypes of asymptomatic increase in serum concentration of creatine phosphokinase (CK) and muscle cramps with myoglobinuria. The severe end of the spectrum includes progressive muscle diseases that are classified as Duchenne/Becker muscular dystrophy when skeletal muscle is primarily affected and as DMD-associated DCM when the heart is primarily affected. Duchenne muscular dystrophy (DMD) usually presents in early childhood with delayed motor milestones including delays in walking independently and standing up from a supine position. Proximal weakness causes a waddling gait and difficulty climbing stairs, running, jumping, and standing up from a squatting position. DMD is rapidly progressive, with affected children being wheelchair dependent by age 12 years. Cardiomyopathy occurs in almost all individuals with DMD after age 18 years. Few survive beyond the third decade, with respiratory complications and progressive cardiomyopathy being common causes of death. Becker muscular dystrophy (BMD) is characterized by later-onset skeletal muscle weakness. With improved diagnostic techniques, it has been recognized that the mild end of the spectrum includes men with onset of symptoms after age 30 years who remain ambulatory even into their 60s. Despite the milder skeletal muscle involvement, heart failure from DCM is a common cause of morbidity and the most common cause of death in BMD. Mean age of death is in the mid-40s. DMD-associated DCM is characterized by left ventricular dilation and congestive heart failure. Females heterozygous for a DMD pathogenic variant are at increased risk for DCM.

Clinical features

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Imported from Human Phenotype Ontology (HPO)

  • Cardiac arrhythmia
  • Muscular dystrophy
  • Muscle weakness
  • Myalgia
  • Elevated circulating creatine kinase concentration
  • Abnormal EKG
  • Hyporeflexia
  • Cardiomyopathy
  • Calf muscle pseudohypertrophy
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Inheritance pattern

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X-linked recessive inheritance

Conditions tested

Target population

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Not provided

Clinical validity

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Deletions account for 60–65% of cases of BMD and DMD, while duplications cause another 10–15% and the remainder may be due to point mutations which are not detected with this methodology.

Citations
  • Duchenne Muscular Dystrophy and Becker Muscular Dystrophy Confirmed by Multiplex Ligation-Dependent Probe Amplification: Genotype-Phenotype Correlation in a Large Cohort. - PubMed ID: 28079318

Clinical utility

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Establish or confirm diagnosis

Citations
  • Identification of deletions and duplications of the DMD gene in affected males and carrier females by multiple ligation probe amplification (MLPA). - PubMed ID: 15841391

Practice guidelines

  • ACMG Algorithm, 2022
    American College of Medical Genetics and Genomics, Algorithm, ELEVATED CREATINEKINASE(CK)-MM , Genetic Neuromuscular Disorders, 2022
  • ACMG ACT, 2020
    American College of Medical Genetics and Genomics, Newborn Screening ACT Sheet, No Pathogenic Variant in Dystrophin (DMD) Gene after elevated creatine kinase muscle isoform (CK-MM), Genetic Neuromuscular Disease, 2020
  • ACMG ACT, 2020
    American College of Medical Genetics and Genomics, Newborn Screening ACT Sheet, Elevated creatine kinase muscle isoform (CKMM), Genetic Neuromuscular Disease, 2020
  • ACMG ACT, 2019
    American College of Medical Genetics and Genomics, Newborn Screening ACT Sheet, Pathogenic Variant in Dystrophin (DMD Gene) and elevated creatine kinase muscle isoform (CK-MM), Duchenne and Becker Muscular Dystrophy, 2019
  • ACMG ACT, 2012
    American College of Medical Genetics & Genomics Genetic Testing ACT Sheet, Duchenne and Becker Muscular Dystrophy, 2012

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