Cytochrome P450 2C19 polymorphisms and valproic acid-induced weight gain.

OBJECTIVES: Cytochrome P450 (CYP) 2C19 plays a role in the biotransformation of clinically relevant drugs as well as endogenous compounds, including sex hormones, which are known to be modulators of food intake and energy balance in humans. We attempted to investigate the influence of CYP2C19 polymorphisms on valproic acid (VPA)-induced weight gain. MATERIALS AND METHODS: This retrospective longitudinal study included 85 VPA-treated and 93 carbamazepine (CBZ)-treated (as a reference) young patients with epilepsy. The body mass index (BMI) gap between the patient's BMI and the cutoff value for being overweight was calculated in each patient during the follow-up period. The longitudinal associations of the CYP2C19 genotype with the BMI gap and risk for becoming overweight during VPA or CBZ therapy were examined retrospectively using the generalized estimating equations approach and the Kaplan-Meier method. RESULTS: During the follow-up period, the values of the BMI gap were significantly greater (P = 0.002 or P = 0.005) and the cumulative incidence of becoming overweight tended to be higher (P = 0.032) in the VPA-treated female patients with one or two loss-of-function CYP2C19 alleles than in the females without the loss-of-function CYP2C19 alleles. No associations were observed among the VPA-treated male patients and CBZ-treated male and female patients (P > 0.05). CONCLUSIONS: This is the first report to show a relationship between the CYP2C19 polymorphism and VPA-induced weight gain in female patients with epilepsy. Further investigations are needed to verify these findings.

Molecular basis of intermittent maple syrup urine disease: novel mutations in the E2 gene of the branched-chain alpha-keto acid dehydrogenase complex.

The E2 gene of the branched-chain alpha-keto acid dehydrogenase (BCKDH) complex was studied at the molecular level in three patients with intermittent maple syrup urine disease (MSUD). All three patients had higher BCKDH activity than did those with the classical phenotype. In the first patient, a single base substitution from A to G in intron 8 created a new 5' splice site and caused an insertion of 126 nucleotides between exons 8 and 9 by activating an upstream cryptic 3' splice site in the same intron. The predicted mRNA encoded a truncated protein with 282 amino acids including 4 novel ones at the carboxyl terminus, compared with the normal protein with 421 amino acids. In vitro, the region from the patient but not from a normal control was recognized and was recovered as a novel exon, indicating that the single substitution was responsible for incorporation of the region into mRNA. This mutation probably supports an exon definition model in which the spliceosome recognizes a 3' splice site and then scans downstream for an acceptable 5' splice site, thereby defining an exon. The second patient was homozygous for a G to T transversion at nucleotide 1463 in exon 11, which predicted a substitution of the termination codon by a leucine residue and the addition of 7 extra amino acids at the carboxyl terminus. For each mutation, these two patients were homozygous and their parents were heterozygous. The third patient was a compound heterozygote for a C to G transversion at nucleotide 309 in exon 4 and a G to A transition at nucleotide 1165 in exon 9, causing an Ile-to-Met substitution at amino acid 37 and a Gly-to-Ser substitution at amino acid 323, respectively. Taken together, these results indicate that the molecular basis of intermittent phenotype MSUD in some patients can be due to mutations in the E2 gene, giving rise to a low but significant residual activity of the BCKDH complex.

Heterogeneous phenotypes of mitochondrial encephalomyopathy in a single kindred.

Five patients with mitochondrial disorders in a single family showed marked heterogeneity of clinical signs and symptoms. Two patients had the syndrome of mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes; one had blepharoptosis, seizures, and diabetes insipidus; and two had a nonspecific encephalomyopathic disorder. This family supports the concept of a "mitochondrial cytopathy."

Familial mitochondrial encephalomyopathy with stroke-like episodes and episodic disturbances of consciousness: a study of pedigree including three generations with multisystemic abnormalities.

We report here two cases in a family with pleomorphic clinical features which include mitochondrial myopathy, encephalopathy, stroke-like episodes, episodic disturbances of consciousness and other multisystemic abnormalities. The other signs observed in multisystemic abnormalities were ophthalmoplegia, short stature, diabetes mellitus, diabetes insipidus, renal dysfunction, optic atrophy, retinal degeneration, impairment of hearing and mental retardation or deterioration. A symptomatological variation was observed in cases in the same family. It is suggested that these widely varying symptoms may be expressions caused by a common biochemical defect which involves different tissues in different individuals in the family. The syndromes observed in the present cases were compared with other possibly-related mitochondrial encephalomyopathies.

Muscle fiber type transformation in nemaline myopathy and congenital fiber type disproportion.

In a morphometric study on biopsied muscles from 5 patients with nemaline myopathy (NM) and 5 with congenital fiber type disproportion (CFTD), the common findings were relative type 1 fiber smallness, type 1 fiber predominance and occasional hypertrophic type 2 fibers. In NM, the relatively larger type 1 fibers increased in number with age in parallel with a decrease in the number of normal to hypertrophic type 2 fibers, reflecting active fiber type transformation from type 2 to type 1, which resulted in striking type 1 fiber predominance. The presence of scattered non-atrophic type 2C fibers also reflected active fiber type transformation because the fibers during the maturational or degenerating process are known to show the type 2C reaction on ATPase staining. On the other hand, the type 1 fibers in CFTD were small in caliber and showed minimal variation in size, suggesting practically no fiber type transformation from hypertrophic type 2 to type 1.

An electron microscopical study of the T-system in biopsied muscles from Fukuyama type congenital muscular dystrophy.

The behavior of the tubular system in muscles from six patients with Fukuyama type congenital muscular dystrophy (FCMD) was examined by electron microscopy using a lanthanum nitrate stain for a comparison with that in Duchenne muscular dystrophy (DMD). In FCMD, many fibers showed morphological changes of the T-system as follows: aggregated tubular components forming honeycomb-like structures, focal dilatation of T-tubules with tangle formation, and numerous longitudinally projecting tubules, which were quite similar to those found in cases with DMD. The fibers with abnormal T-systems occasionally showed ultrastructural characteristics of regenerating fibers, including excessive ribosome particles, immaturely organized myofibrils, and an increased number of internal nuclei and satellite cells. The present results suggested that there was no qualitative difference in the behavior of the T-system between FCMD and DMD, and the morphological changes of the T-system in dystrophic muscles were not primary lesions initiating myonecrosis but reflected the behavior of sarcotubular formation in the process of muscle regeneration.

Behavior of sarcotubular system formation in experimentally induced regeneration of muscle fibers.

To examine the behavior of transverse (T)-tubule formation in experimentally-induced regenerating fibers, a local anesthetic, bupivacaine hydrochloride, was injected directly into the rat soleus muscle to cause myonecrosis. The regenerating fibers following necrosis were then examined by electron microscopy using lanthanum nitrate which clearly demonstrated the sarcotubular system. In the early stage of regeneration within 7 days after muscle necrosis, the T-tubules seemed to be composed of markedly proliferated subsarcolemmal caveolae with occasional honeycomb structure formation. Around 10 days, the T-tubules in regenerating fibers were tortuously and irregularly arranged with focal dilatation in diameter, and extended longitudinally along the axis of well organized myofibrils. As the regenerating fibers matured, the sarcotubular system, irregular in course and in shape, gradually became organized into a regular transverse position against the myofibrils, along with a marked decrease in longitudinally arranged tubular components. These morphological findings of the early T-tubule formation seen in the present study were similar to those found in early myogenesis, and in biopsied muscles from cases of polymyositis and progressive muscular dystrophy.