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Título

Later diagnosis of Duchenne Muscular Dystrophy in Brazilian patients: where could we improve?

Resumo

Introduction: Duchenne muscular dystrophy (DMD) is caused by a mutation in the dystrophin geneand is the most common form of childhood-onset muscular dystrophy affecting approximately 1 in 3500 newborn boys. The disease is progressive and most patients exhibit signs of muscle weakness before 6 years. Despite all the advances in management and treatment of DMD over the last decades, the mean age at diagnosis of DMD has been reported to be around the age of 4.5-5 years in several countries with a delay of about 2 years between the first symptoms are noted, and the diagnosis.
Objective and method: This retrospective study had objective to investigate the age at diagnosis of disease in a group of Brazilian patients followed in a tertiary center.
Results: We identified 122 Brazilian boys with phenotype/genotype compatible with DMD in the last 7 years (2014-2021). The most common mutational event was represented by intragenic deletions, accounting for 58% (71/122) of all mutations. Duplications accounted for 14% and 20% of patients had a point mutation (including 12/122 with nonsense mutation). In 7 boys (5%) was found an intronic mutation and in 2 the muscle biopsy confirmed absence or near absence of dystrophin in the muscle. The mean age at onset of the disease was 3,3 years. Frequent falls were the more frequent symptoms (55/122) at initial clinical presentation. The mean age at diagnosis was 6,9 years . The age of diagnosis was defined as the age of molecular test was realized, confirming the disease. Steroid therapy was initiated in 120/122 patients (prednisolone 36/120 or deflazacort 84/120). The mean age at start treatment with steroid was 7,3 years . Thirty-seven (30%) lost the capacity to walk until the last evaluation. The mean age of lost was 10 years. In all patients, CK levels were markedly increased in the early stages of the disease.
Conclusion: In this group of Brazilian patients with DMD, an important delay in diagnosis was observed, which led to a delay in the beginning of steroid therapy, when compared to the onset of initial symptom. This late onset of therapy is probably related to an earlier age of loss of capacity to walk observed in this group. Despite the availability of access to molecular testing, we still observed difficult in recognizing the disease, which may be improved with wider dosage of serum CK in patients with motor/global development delay and weakness.