Late Onset Multiple Acyl-CoA Dehydrogenase Deficiency (MADD) Myopathy Misdiagnosed as Polymyositis

Late-onset myopathies

PURPOSE OF REVIEW

Late-onset myopathies are defined as muscle diseases that begin after the age of 50 years. Some myopathies present classically in the elderly, whereas others may have a variable age of onset, including late-onset presentation. The purpose of this review is to summarize and comment on the most recent evidence regarding the main diagnosis of late-onset myopathies focusing on genetic causes.

RECENT FINDINGS

Although late-onset myopathies (LOM) are expected to be predominantly acquired myopathies, some common genetic myopathies, such as facioscapulohumeral muscular dystrophy (FSHD), can present late in life, usually with an atypical presentation. In addition, metabolic myopathies, which are classically early-onset diseases, are also diagnoses to be considered, particularly as they may be treatable. Late-onset multiple acyl-CoA dehydrogenase deficiency (MADD) has recently been identified as a cause of subacute LOM with a dramatic response to riboflavin supplementation.

SUMMARY

Inclusion body myositis is the most frequent of all LOM. Myotonic dystrophy type 2, FSHD and oculopharyngeal muscular dystrophy are the most frequent causes of genetic LOM. We summarize the major differential diagnoses and the clinical features on clinical examination that are suggestive of a genetic diagnosis to provide a diagnostic approach.

A systematic review of late-onset and very-late-onset multiple acyl-coenzyme A dehydrogenase deficiency: Cohort analysis and patient report from Taiwan

Multiple acyl-coenzyme A dehydrogenase deficiency (MADD) is a rare metabolic disorder with a dramatic clinical presentation. It was recently discovered that MADD may present at an advanced age. The clinical and laboratory data of an index patient and patients previously diagnosed at our institution were collected. A systematic review of previous studies retrieved from the PubMed, MEDLINE, and Embase databases published by February 1, 2020 was performed to collect patients with very-late-onset MADD (VLO-MADD, onset age > 60 years) globally and patients with late-onset MADD (LO-MADD, onset age < 60 years) in Taiwan. The clinical characteristics of the VLO-MADD patients were compared to those of LO-MADD patients. We report a patient with VLO-MADD who developed the first symptom at the age of 61 years. The patient presented with a Reye-like syndrome after taking aspirin for coronary artery disease. Repeated bouts of weakness were noted. Two variants of c.250 G > A (;) 419C > T were observed in the ETFDH gene. Another four patients with VLO-MADD were identified globally. Eighteen patients with LO-MADD were collected from our department and previously reported patients in Taiwan. There was no difference in the clinical symptoms (except for the onset age) or laboratory data between these two groups. Homozygous variants were not observed in any patients in the VLO-MADD group but were detected in 12 patients (66.6%) in the LO-MADD group (p = 0.014). Patients with MADD may first show symptoms in their 6th decade or beyond. The disease course may lead to erroneous diagnoses in this age group.