Aya Ohkuma

ETFDH mutations, CoQ10 levels, and respiratory chain activities in patients with riboflavin-responsive multiple acyl-CoA dehydrogenase deficiency

Multiple acyl-CoA dehydrogenase deficiency (MADD) is a metabolic disorder due to dysfunction of electron transfer flavoprotein (ETF) or ETF-ubiquinone oxidoreductase (ETF-QO). Mutations in ETFDH, encoding ETF-QO have been associated with both riboflavin-responsive and non-responsive MADD as well as a myopathic form of CoQ(10) deficiency, although pathomechanisms responsible for these different phenotypes are not well-defined. We performed mutation analysis in four Taiwanese MADD patients. Three novel ETFDH mutations were identified in four patients and all harbored the p.A84T mutation. Muscle CoQ(10) levels and respiratory chain activities measured in two patients were normal. Three patients improved on riboflavin together with carnitine. Our results show that not all MADD patients have CoQ(10) deficiency. Based upon our data, riboflavin and carnitine may be the first-line treatment for MADD.

A Congenital Muscular Dystrophy with Mitochondrial Structural Abnormalities Caused by Defective De Novo Phosphatidylcholine Biosynthesis

Congenital muscular dystrophy is a heterogeneous group of inherited muscle diseases characterized clinically by muscle weakness and hypotonia in early infancy. A number of genes harboring causative mutations have been identified, but several cases of congenital muscular dystrophy remain molecularly unresolved. We examined 15 individuals with a congenital muscular dystrophy characterized by early-onset muscle wasting, mental retardation, and peculiar enlarged mitochondria that are prevalent toward the periphery of the fibers but are sparse in the center on muscle biopsy, and we have identified homozygous or compound heterozygous mutations in the gene encoding choline kinase beta (CHKB). This is the first enzymatic step in a biosynthetic pathway for phosphatidylcholine, the most abundant phospholipid in eukaryotes. In muscle of three affected individuals with nonsense mutations, choline kinase activities were undetectable, and phosphatidylcholine levels were decreased. We identified the human disease caused by disruption of a phospholipid de novo biosynthetic pathway, demonstrating the pivotal role of phosphatidylcholine in muscle and brain.

Clinical and genetic analysis of lipid storage myopathies

Causative genes have been identified only in four types of lipid storage myopathies (LSMs): SLC22A5 for primary carnitine deficiency (PCD); ETFA, ETFB, and ETFDH for multiple acyl‐coenzyme A dehydrogenation deficiency (MADD); PNPLA2 for neutral lipid storage disease with myopathy (NLSDM); and ABHD5 for neutral lipid storage disease with ichthyosis. However, the frequency of these LSMs has not been determined. We found mutations in only 9 of 37 LSM patients (24%): 3 in SLC22A5; 4 in MADD‐associated genes; and 2 in PNPLA2. This low frequency suggests the existence of other causative genes. Muscle coenzyme Q10 levels were normal or only mildly reduced in two MADD patients, indicating that ETFDH mutations may not always be associated with CoQ10 deficiency. The 2 patients with PNPLA2 mutations had progressive, non‐episodic muscle disease with rimmed vacuoles. This suggests there is a different pathomechanism from other LSMs. Muscle Nerve 39: 333–342, 2009

Distal lipid storage myopathy due to PNPLA2 mutation

Distal myopathy is a group of heterogeneous disorders affecting predominantly distal muscles usually appearing from young to late adulthood with very rare cardiac complications. We report a 27-year-old man characterized clinically by distal myopathy and dilated cardiomyopathy, pathologically by lipid storage, and genetically by a PNPLA2 mutation. The patient developed weakness in his lower legs and fingers at age 20 years. Physical examination at age 27 years revealed muscle weakness and atrophy predominantly in lower legs and hands, and severe dilated cardiomyopathy. The patient had a homozygous four-base duplication (c.475_478dupCTCC) in exon 4 of PNPLA2.

Effect of l-DOPA on nitric oxide production in striatum of freely mobile mice

In Parkinsons disease, nitric oxide (NO) and other free radicals are thought to be involved in neuronal degeneration. Furthermore, L-DOPA is suggested to have a cytotoxic action on dopaminergic neurons. We studied 24-h NO production and the effect of L-DOPA on this in freely mobile mice using in vivo microdialysis. A microdialysis probe was implanted into the right striatum 12 h before the experiment. This dialysis probe was perfused with Ringer solution for 100 min, then with 20, 50, or 100 nM L-DOPA for 20 min, and finally with Ringer solution. Dialysate fractions were collected every 20 min for 4 h. Production of nitrite and total NO were significantly higher during daytime than during nighttime. Nitrate production was increased significantly by L-DOPA. NO production in the striatum appears to exhibit a diurnal rhythm and to increase with exposure to L-DOPA.

Central nervous system and muscle involvement in an adolescent patient with riboflavin-responsive multiple acyl-CoA dehydrogenase deficiency

We report an adolescent case of late-onset riboflavin-responsive multiple acyl-CoA dehydrogenase deficiency (MADD) characterized by intermittent nausea and depressive state as early symptoms. At the age of 12 years and 11 months, the patient experienced intermittent nausea and vomiting, and depressive state. She was on medication for depression for 5 months but it was ineffective. Brain magnetic resonance imaging showed disseminated high-intensity areas in the periventricular white matter and in the splenium of the corpus callosum on T2-weighted images and fluid-attenuated inversion-recovery images. Progressive muscle weakness occurred and blood creatine kinase level was found to be elevated. The muscle biopsy revealed lipid storage myopathy. Urine organic acid analysis and mutation analysis of the ETFDH gene confirmed the diagnosis of MADD. With oral supplements of riboflavin and l-carnitine, in addition to a high-calorie and reduced-fat diet, her clinical symptoms improved dramatically. Early diagnosis is important because riboflavin treatment has been effective in a significant number of patients with MADD.

QSART in idiopathic pure sudomotor failure

QSART (quantitative sudomotor axon reflex testing) was performed in a patient with idiopathic pure sudomotor failure. Generalized reduction in thermoregulatory sweating and complete absence of axon reflex sweating were observed, suggesting a deficit of sweat gland cholinergic synaptic transmission or receptors. QSART responded promptly to treatment. Putative pathophysiological mechanisms are discussed.

Neurosarcoidosis presenting as spontaneously remitting hypersomnia

A 38-year-old woman was first admitted to our hospital in November 2007 because of excessive daytime somnolence and short-term memory disturbance. She reported that her speech had gradually become slower starting in April 2007. Severe fatigue and somnolence had developed at the beginning of August 2007. She felt very sleepy and had to take long naps, generally sleeping all day except for at meal times, and she was therefore unable to do housework. Hypersomnia and chronic fatigue persisted after she was admitted to the hospital. On admission, her body temperature was 35.8 C, heart rate was 99 beats/min, and blood pressure was 118/56 mm Hg. Physical and neurological findings were uninformative with the exception of mild cognitive dysfunction; her MiniMental State Score was 23/30. She had daytime somnolence and her Epworth Sleepiness Score [4] was 18 points. Blood cell counts and serum levels of sodium, potassium, creatinine, and urea nitrogen as well as liver enzymes, glucose, angiotensin-converting enzyme (ACE), and adenosine deaminase (ADA) were all within normal ranges. However, cerebrospinal fluid (CSF) cell count (17/ll) and protein level (139 mg/dl) were elevated. Activity of ACE (0.2 U/l) and ADA (2.2 IU/l) in the CSF were within the normal range, and CSF culture and cytology were negative. CSF hypocretin-1 (orexin A) concentration was decreased (82.8 pg/ml: lower limit of normal = 110 pg/ml) [5]. T2-weighted magnetic resonance imaging (MRI) showed high-intensity signals in the brainstem, hypothalamus, basal ganglia, and white matter surrounding the lateral ventricle (Fig. 1a). Gadolinium-enhanced T1weighted MRI (Gd-MRI) demonstrated numerous small spots of high intensity in the bilateral thalamus, hypothalamus, and basal ganglia (Fig. 1b). Bilateral hilar lymphadenopathy (BHL) was absent on chest X-ray. Neither chest computed tomography (CT) nor whole body gallium scanning revealed abnormal lesions. The patient was clinically diagnosed with central nervous system (CNS) sarcoidosis associated with secondary hypersomnia, although the diagnosis was not confirmed by laboratory data at that time. The hypersomnia spontaneously and gradually improved. Therefore, no medication was initiated, and she was discharged from the hospital in December 2007. Six months later, the hypersomnia and memory disturbance had disappeared completely. The high-intensity areas in the bilateral thalamus and basal ganglia on MRI T2-weighted imaging, as well as the numerous small spots on gadolinium-enhanced T1-weighted imaging, had disappeared by May 2008 (Fig. 1c, d). Mild memory disturbance recurred in September 2008, and new bilateral cerebral white matter lesions were seen on brain MRI, which demonstrated foci of abnormal signal intensity in the bilateral white matter; these showed decreased signal Y. Nakazato (&) S. Kondo A. Ohkuma Y. Ito N. Tamura N. Araki Department of Neurology, Faculty of Medicine, Saitama Medical University, 38 Morohongo, Moroyama, Iruma-gun, Saitama 350-0495, Japan e-mail: nakachan@saitama-med.ac.jp