Characteristics of disease progression and genetic correlation in ambulatory Iranian boys with Duchenne muscular dystrophy

Abstract

Background Duchenne muscular dystrophy (DMD) is the most common muscular dystrophy in the pediatric population. The manifestations of this disease include progressive muscle weakness, gait dysfunction, and motor impairment, leading to a loss of ambulation by the age of 13 years. Molecular diagnosis is the standard diagnostic tool for DMD. This study aimed to investigate disease progression and genetic patterns in Iranian ambulant boys and to find the correlation between genotypes and motor function phenotypes. Methods This study was performed on 152 DMD patients. Clinical history, including the disease phenotype, steroid therapy, and the North Star Ambulatory Assessment (NSAA) score, was taken for all the patients. Molecular diagnoses were confirmed by multiplex ligation-dependent probe amplification and next-generation sequencing tests. Results A total of 152 Iranian DMD patients were examined in this study. The mean age at the time of disease onset was 4.04 ± 2.00 years, and the mean age at diagnosis was 5.05 ± 2.08 years. The mean age of ambulation loss was 10.9 years. Contracture was reported in 38.9% of cases. In terms of age, the mean total NSAA score showed a peak at 4 years of age, with a mean NSAA score of 24. Annual changes in the NSAA score were determined for all cases, based on the mutation type and exon site. Deletion mutation was found in 79.1% of cases, duplication in 6.8%, nonsense in 12.8%, and splice site in 1.4%. The most common single exon deletion was exon 44 (5.3%), and the most common multiexon deletions were attributed to exons 45–50 and exons 45–52 (4.6%). The results did not indicate any correlation between the mutation type and age at the time of disease onset, loss of ambulation age, and wheelchair dependence; however, a significant association was found between contracture and mutation type. The results showed a significant difference in the NSAA score between the deletion and nonsense groups at the age of 3 years (P = 0.04). No significant correlation was found between the phenotype and exon site. Overall, 91.1% of the study population had a history of corticosteroid use, and 54.1% showed compliance with rehabilitation therapy. Conclusion This study demonstrated the phenotypes and mutational features of Iranian DMD boys and provided information regarding the natural motor history of the disease, disease progression, diagnosis, and status of DMD management in Iran. The present findings can promote the development of clinical trials and future advanced molecular therapies in Iran.

Duchenne Muscular Dystrophy from Brain to Muscle: The Role of Brain Dystrophin Isoforms in Motor Functions

“…Furthermore, the survival analysis for the follow-up evaluation of the patients revealed that, with the progression of the disease, the patients in Group 1 were more prone to becoming wheelchairbound at a younger age compared to those in Group 2 (p = 0.004), as depicted in Table 3 and Figure 4. The reported data on the age of wheelchair dependency in DMD patients of different populations are as follows: in India, the age is 10.4 years [18] and 13 years [34]; in Iran, the age is 10.9 years [35]; in Saudi Arabia, the age is 10.1 years [36]; in the Netherlands, the age is 9.7 years [37]; and in the UK, according to the North Star database and other related studies, the age is 13 years [10,38]. The variability observed in the age at which individuals become dependent on wheelchairs in different populations can potentially be attributed to regional disparities in patient management, healthcare resources, the socioeconomic background of the patients, genetic factors, and the influence of disease modifier genes specific to certain populations [30,[39][40][41][42].…”

Características clínicas y moleculares de pacientes con distrofia muscular de Duchenne y de Becker en el Hospital Nacional Guillermo Almenara Irigoyen, Perú, 1997-2007

“…En nuestro estudio, la edad promedio en el momento de evaluación molecular fue 6,5 años en pacientes con DMD/ DMB. Esta cifra es relativamente superior a estudios realizados en Italia, Irán y Noruega que han informado edades promedios de 3,90, 4,00 y 5,05 años, respectivamente (18)(19)(20). Además, un estudio peruano realizado en cuatro establecimientos de referencia nacional entre el 2015 al 2018 reportaron una edad promedio de 9,8 años para la evaluación molecular.…”

Reclassification of DMD Duplications as Benign: Recommendations for Cautious Interpretation of Variants Identified in Prenatal Screening

“…As of 31 May 2022, more than 7100 DMD mutations, including exon deletions, exon duplications, and point mutations, have been described in the Leiden Open Variation Database (LOVD) and the UMD-DMD France Database. Exon duplication is the most common mutation, accounting for approximately 7% of all DMD pathogenic mutations [ 7 , 8 ]. Approximately 1 in 5224 fetuses carry maternally inherited exon duplications of the DMD gene [ 9 ].…”