Muscle carnitine deficiency: adult onset lipid storage myopathy with sensory neuropathy

Carnitine and Depression

Depression has become one of the most common mental diseases in the world, but the understanding of its pathogenesis, diagnosis and treatments remains insufficient. Carnitine is a natural substance that exists in organisms, which can be synthesized in vivo or supplemented by intake. Relationships of carnitine with depression, bipolar disorder and other mental diseases have been reported in different studies. Several studies show that the level of acylcarnitines (ACs) changes significantly in patients with depression compared with healthy controls while the supplementation of acetyl-L-carnitine is beneficial to the treatment of depression. In this review, we aimed to clarify the effects of ACs in depressive patients and to explore whether ACs might be the biomarkers for the diagnosis of depression and provide new ideas to treat depression.

Investigation of adult-onset multiple acyl-CoA dehydrogenase deficiency associated with peripheral neuropathy

Multiple Acyl-CoA dehydrogenase deficiency (MADD), one of the most common lipid storage myopathies (LSMs), is a heterogeneous inherited muscular disorder that is pathologically characterized by numerous lipid droplets in muscle fibers due to lipid metabolism disturbance. MADD exhibits a wide range of clinical features, including skeletal muscle weakness and multisystem dysfunctions. However, MADD, as well as other types of LSM, associated with peripheral neuropathy has rarely been reported during the past four decades. Here, we present four Chinese patients affected by MADD with peripheral neuropathy in our neuromuscular center. Clinically, these four patients showed skeletal muscle weakness and prominent paresthesia. Muscle biopsy detected characteristic myopathological patterns of LSM, such as obvious lipid droplets in muscle fibers. Sural nerve biopsy revealed a severe reduction in number of myelinated nerve fibers, which is a typical neuropathological pattern of peripheral neuropathy. Causative ETFDH mutations were found in all four cases. The skeletal muscle weakness was rapidly improved after some treatments while paresthesia showed unsatisfactory improvement. The features of previously reported patients of this specific type are also summarized in this paper. We propose that MADD with peripheral neuropathy may be a new phenotypic subtype because the pathology and reaction to riboflavin treatment are different from those of traditional MADD, although further research on the precise pathogenesis and mechanisms is needed.

[Lipid storage myopathies. A clinical and pathobiochemical challenge]

Lipid storage myopathies are a clinically and genetically heterogeneous group of muscle diseases characterized by an accumulation of lipid in skeletal muscle. Currently four different groups of lipid storage myopathies are described: primary carnitine deficiency (PCD), multiple acyl-CoA dehydrogenase deficiency, primary and secondary coenzyme Q10 deficiency and neutral lipid storage diseases. It might be due to their rareness and considerable clinical variability that these disorders are frequently disregarded in neurological differential diagnosis. This article provides a synopsis of several new aspects of pathophysiology, symptoms, diagnostic tools and current therapeutic approaches of lipid storage myopathies.