Clinical features of children diagnosed with Duchenne muscular dystrophy under two years

Aim: Duchenne muscular dystrophy (DMD) is a hereditary and progressive disease of muscle fiber degeneration caused by deletion, duplication or other mutations in the Xp21 gene, occurring one in 3600-6000 live male births. Although there are histological and laboratory (creatine kinase) indicators of myopathy in infancy in boys with DMD, they are clinically asymptomatic. In the first 2 years of life delayed gross motor development is encountered. Symptoms become noticeable at 3-5 years of age. In later years, signs such as prominent lumbar lordosis and gastrocnemius pseudohypertrophy appear. The average diagnosis can be made at 3-5 years. In this study, clinical features of patients diagnosed under 2 years of age were examined. Materials and Methods: This study was carried out at Hacettepe University Faculty of Medicine, Department of Child Health and Diseases, Department of Child Neurology between 15 February and 15 June 2019, retrospectively from medical charts. Between January 2014 and January 2019, patients under 2 years of age diagnosed with DMD (multiple ligation-dependent probe amplification, chromosome microarray and dystrophin gene sequencing) were identified in our hospital. Patients' age at diagnosis, reasons for evaluation, physical examination findings at the time of evaluation, gross motor development, speech and cognitive- vii social development, prenatal, natal, postnatal clinical characteristics, creatine kinase (CK) level and liver function tests, and family history. Results: 127 patients with a diagnosis of DMD between 41.54 ± 20.32 months (6-113 months) were included in the study. The age of diagnosis ranged from 14.5 ± 6.5 months (5 days-24 months). At the time of diagnosis 84.3% (n = 107) incidentally had elevated CK value, 7.1% (n = 9) had delayed walking, and 6.3% (n = 8) of the patients had delayed speech skills. Genetic mutation was studied in all patients with 78% (n = 99) deletions, 3.9% (n = 5) duplication, 14.1% (n = 18) point mutations, whereas in 3.9% (n = 5) mutation could not be detected. The diagnosis was made by muscle biopsy in 4.7% (n = 6) of the patients. DMD carriage was detected in 4% (n = 5) of all mothers. Conclusion: CK elevation in blood is a valuable parameter for the early diagnosis of DMD. New treatment modalities are under development are promising for DMD. Thus, the age of diagnosis becomes more important. Early diagnosis may lead to early interventions and treatment as well as genetic counselling. Keywords: Duchenne muscular dystrophy, increased CK, muscular dystrophy