Tumor Necrosis Factor Receptor SF10A (TNFRSF10A) SNPs Correlate With Corticosteroid Response in Duchenne Muscular Dystrophy

Background

Duchenne muscular dystrophy (DMD) is a rare and severe X-linked muscular dystrophy in which the standard of care with variable outcome, also due to different drug response, is chronic off-label treatment with corticosteroids (CS). In order to search for SNP biomarkers for corticosteroid responsiveness, we genotyped variants across 205 DMD-related genes in patients with differential response to steroid treatment.

Methods and Findings

We enrolled a total of 228 DMD patients with identified dystrophin mutations, 78 of these patients have been under corticosteroid treatment for at least 5 years. DMD patients were defined as high responders (HR) if they had maintained the ability to walk after 15 years of age and low responders (LR) for those who had lost ambulation before the age of 10 despite corticosteroid therapy. Based on interactome mapping, we prioritized 205 genes and sequenced them in 21 DMD patients (discovery cohort or DiC = 21). We identified 43 SNPs that discriminate between HR and LR. Discriminant Analysis of Principal Components (DAPC) prioritized 2 response-associated SNPs in the TNFRSF10A gene. Validation of this genotype was done in two additional larger cohorts composed of 46 DMD patients on corticosteroid therapy (validation cohorts or VaC1), and 150 non ambulant DMD patients and never treated with corticosteroids (VaC2). SNP analysis in all validation cohorts (N = 207) showed that the CT haplotype is significantly associated with HR DMDs confirming the discovery results.

Conclusion

We have shown that TNFRSF10A CT haplotype correlates with corticosteroid response in DMD patients and propose it as an exploratory CS response biomarker.

Why are some patients with Duchenne muscular dystrophy dying young: An analysis of causes of death in North East England

INTRODUCTION

Duchenne muscular dystrophy (DMD) is the most common inherited muscle disease in children. Recent years have seen an increase in age of survival into adulthood following the introduction of proactive standards of care. We reviewed mortality in DMD in our population in order to identify potential underlying risk factors for premature death and improve clinical care.

METHOD

A retrospective case note review of all deaths in the DMD population over the last 10 years in North East England. We identified 2 groups of patients: patients who died from underlying cardiac and/or respiratory failure (group 1) and patients who died unexpectedly in the absence of underlying cardio-respiratory failure (group 2).

RESULTS

Detailed information was available on 21 patients. Mean age of death in group 1 (17 patients) was 23.9 (14.4-39.5) years, in group 2 (4 patients) 14 (12.7-14.9) years. Causes of death in group 2 were acute pneumonia, cardiac arrest, acute respiratory distress and multi-organ failure. Across both groups we identified concerns regarding respiratory failure, inadequate nutrition, non-attendance at appointments, suboptimal coordination of care and decreased psychological wellbeing. In group 2, fat embolism, cardiac arrhythmia and adrenal insufficiency were also potential contributing factors.

CONCLUSIONS

The main cause of death in DMD in our population remains cardio-respiratory failure. Four patients (19%) died in their teenage years in the absence of severe cardiorespiratory failure. A more thorough understanding of the impact of DMD and its treatment on all organs systems is required to minimise the risk of an untimely death.

Psycho-organic symptoms as early manifestation of adult onset POMT1-related limb girdle muscular dystrophy

We report two siblings of Croatian consanguineous healthy parents with a novel homozygous missense mutation in the POMT1 gene, presenting with intellectual disability and psychotic, in particular hallucinatory symptoms and abnormal brain MRIs, preceding classical symptoms of limb-girdle muscular dystrophy by several years. Weakness became apparent in early adulthood and both siblings remained ambulant into the 3rd and 4th decade of life. The muscle biopsy showed reduced α-dystroglycan compatible with the POMT1 defect. This case report extends the phenotypic spectrum of POMT1 associated muscular dystrophies to the adult onset limb girdle muscular dystrophies with psycho-organic deficits.