Case history
Case history
A 4-year-old boy presents with a history of ambulation delayed until 18 months of age, toe walking, calf hypertrophy, and proximal hip girdle muscle weakness. His pediatrician suspected cerebral palsy and referred him to an orthopedic surgeon, who found that his creatine kinase levels were greatly elevated. His siblings, a boy of 6 years and a girl of 7 years, are apparently well.
Other presentations
Unusual presentations of dystrophinopathies include asymptomatic elevation of serum creatine kinase (CK), exercise intolerance, dilated cardiomyopathy, malignant hyperthermia, quadriceps myopathy, speech delay, and Xp21 muscular dystrophy appearing in Turner syndrome (i.e., X chromosome monozygote females). For some patients with subclinical DMD the diagnosis is first suspected by family history or the presence of elevated liver enzymes, the reason for which is unclear. These enzymes may include alanine aminotransferase and aspartate aminotransferase.
Because DMD inheritance is X-linked, the overwhelming majority of patients are male. Rarely, female carriers of DMD are manifesting carriers, with mild symptoms or signs of DMD.[5] Some carriers are diagnosed after an incidental finding of elevated serum CK. Occasionally, manifesting carriers can be affected sufficiently to require ventilator use. Symptomatic disease in girls can be explained by Turner syndrome, skewed X chromosome inactivation, translocation of the mutated gene to an autosome, or uniparental disomy (when both copies of a chromosome pair have originated from one parent).
Dystrophinopathy, as a cause of clinical myopathy, is not rare among girls or women, with two studies showing an incidence of nearly 10%.[6] Most symptomatic girls or women present in childhood with proximal muscle weakness, but new weakness in adulthood, myalgias, cramps, and fatigue have been reported as initial symptoms.
Congenital muscular dystrophies, rarely confused with DMD, cause proximal muscle weakness at birth and usually present with hypotonia at birth or soon thereafter. Static to rapidly progressive forms have been described.[7] These patients usually develop predominantly proximal muscle weakness, joint contractures, and occasionally facial muscle weakness. Bulbar musculature is generally spared. About 50% of patients are never able to walk. Scoliosis and chronic alveolar hypoventilation can cause early and severe problems for all children with muscular dystrophy.
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