Biomedical subjects

Hiroshi Mabuchi

Publications and source records attributed to Hiroshi Mabuchi.

At least 109 records · Page 6Linked to original sources

PubMed2002

Calcineurin inhibition attenuates mineralocorticoid-induced cardiac hypertrophy.

BACKGROUND: It remains unclear how mineralocorticoids induce cardiac hypertrophy and fibrosis. Recently, activation of the calcium-dependent phosphatase, calcineurin, has been shown to induce cardiac hypertrophy. In the present study, we examine the role of calcineurin in mineralocorticoid-induced cardiac hypertrophy and fibrosis. METHODS AND RESULTS: Uninephrectomized Wistar-Kyoto rats were placed on a 1.0% NaCl diet and treated with aldosterone (0.75 microg x h(-1)) for 6 weeks with or without the calcineurin inhibitors, FK506 (0.5 mg x kg(-1) x d(-1)) or cyclosporine A (10 mg x kg(-1) x d(-1)). The effect of the angiotensin II type 1 receptor antagonist, losartan (10 mg x kg(-1) x d(-1))on aldosterone-induced cardiac hypertrophy was also studied. Treatment with aldosterone increased the heart weight/body weight ratio, cardiomyocyte size, and collagen amount. The expression of mRNA of both type-III collagen and atrial natriuretic peptide in the heart were increased by aldosterone administration. Both calcineurin activity and its mRNA expression were also increased in aldosterone-induced hypertrophic heart. Treatment with losartan, FK506, or cyclosporine partially prevented aldosterone-induced cardiac hypertrophy and fibrosis. CONCLUSION: These results suggest that calcineurin is involved in the development of cardiac hypertrophy and fibrosis induced by mineralocorticoid excess. Inhibition of calcineurin may therefore prevent cardiac hypertrophy and fibrosis in mineralocorticoid hypertension.

Aldosterone↗

PubMed2002

A novel mutation Lys273Glu in the cardiac troponin T gene shows high degree of penetrance and transition from hypertrophic to dilated cardiomyopathy.

Familial hypertrophic cardiomyopathy (HC) can be caused by mutations in 9 different genes encoding sarcomere proteins expressed in cardiac muscle. To date, only 13 different mutations in the cardiac troponin T (cTnT) gene have been reported to cause HC. Clinical characteristics and prognosis associated with mutations of this gene have not been well characterized owing to the small size and composition of affected families. The aim of this study was to determine the characteristic phenotype of patients with HC caused by a novel cTnT gene mutation, Lys273Glu. Two hundred Japanese probands with HC were screened for mutations in the cTnT gene. The Lys273Glu missense mutation was present in 9 persons from 2 unrelated pedigrees. They exhibited different cardiac morphologies: 1 had a dilated cardiomyopathy-like feature, 7 had left ventricular hypertrophy with normal left ventricular systolic function, and the 6 of them had asymmetric septal hypertrophy. A 1-year-old boy was not evaluated with echocardiography. The mean maximum wall thickness was 18.0 +/- 5.5 mm (range 8 to 24). There were 7 histories of sudden death in 1 of the 2 families. The Lys273Glu substitution in the cTnT gene shows a high degree of penetrance (100% in persons aged >20 years), a high incidence of sudden death, and a partial transition from hypertrophic to dilated cardiomyopathy. Because the location of a mutation appears to influence the development of a phenotype, we suggest that the precise definition of the disease-causing mutation can provide important prognostic information about affected members.

Adolescent↗

PubMed2002

T-peak to T-end interval may be a better predictor of high-risk patients with hypertrophic cardiomyopathy associated with a cardiac troponin I mutation than QT dispersion.

BACKGROUND: Patients with hypertrophic cardiomyopathy (HCM) associated with a deletion of lysine 183 (K183del) in the cardiac troponin I (cTnI) gene suffer sudden cardiac death at all ages. However, the correlation between QT variables and sudden cardiac death in these patients remains uncertain. HYPOTHESIS: We evaluated the correlation between QT variables and sudden cardiac death and/or ventricular tachyarrhythmia (SCD/VT) in patients with HCM associated with the cTnI mutation. METHODS: We analyzed 10 probands with HCM associated with the cTnI gene K183del and their family members. The subjects were divided into three groups: Group A (n = 7), mutation carriers with SCD/VT; Group B (n = 16), mutation carriers without SCD/VT; Group C (n = 24), no mutation carriers. QT intervals were corrected using Bazett's formula. RESULTS: Maximum QTc and corrected QT dispersion were significantly longer in Groups A and B than in Group C. However, there were no differences in either parameter between Groups A and B. On the contrary, the peak-to-end interval of T wave/QT interval in V5 (Tpe) in Group A was significantly longer than that in Groups B and C. Logistic regression analysis revealed that Tpe was a good clinical predictor for SCD/VT in patients with HCM in this study. CONCLUSIONS: These results suggest that Tpe rather than QT dispersion may be one of the best predictors for SCD/VT in patients with HCM associated with the K183del mutation in the cTnI gene.

Adult↗

PubMed2002

Two novel types of contiguous gene deletion of the AVPR2 and ARHGAP4 genes in unrelated Japanese kindreds with nephrogenic diabetes insipidus.

Study of two families containing individuals with nephrogenic diabetes insipidus (NDI) indicated different types of 21.3 kb and 26.3 kb deletions involving the AVPR2 and ARHGAP4 (RhoGAP C1) genes. In the case of the 21.3 kb deletion, the deletion consensus motif (5'-TGAAGG-3') and polypurine runs, known as the arrest site of polymerase alpha, were detected in the vicinity of the deletion junction. Inverted repeats (7/8 matches), believed to potentiate DNA loop formation, flank the deletion breakpoint. We propose this deletion to be the result of slipped mispairing during DNA replication. In the case of the 26.3 kb deletion, the 12,945 bp inverted region with the 10,003 bp internal deletion was accompanied with the 2,509 bp deletion in the 5'-side and the 13,785 bp deletion in the 3'-side. We defined three deletion junctions in this rearrangement (DJ1, DJ2, and DJ3) from the 5'-side. The surrounding sequence of DJ1 (5'-CCC-3') closely resembled that of DJ3 (5'-AGGG-3') (DJ1; 5'-cCCCgaggg-3', DJ3; 5'-ccccAGGG-3'), and DJ1 was located in the 5'-side of DJ3 without any overlapping in sequence. The immunoglobulin class switch (ICS) motif (5'-TGGGG-3') was found around the complementary sequence of DJ3. There was a 10-base palindrome (5'-aGACAtgtct-3') in the alignment of the DJ2 (5'-GACA-3') region. From these findings, we propose a novel mutation process with the rearrangement probably resulting from stem-loop induced non-homologous recombination in an ICS-like fashion. Both patients, despite lacking ARHGAP4, had no morphological, clinical, or laboratory abnormalities except for those usually found in patients with NDI.

Adult↗

PubMed2002

Mutational and haplotype analysis of AGL in patients with glycogen storage disease type III.

Glycogen storage disease type III (GSD III) is a rare autosomal recessive inherited disorder caused by a deficiency of the glycogen-debranching enzyme (AGL). We investigated two GSD III patients and identified four different mutations. Nucleotide sequence analysis revealed patient 1 of Chinese descent to be a compound heterozygote for a novel nonsense mutation, R34X, and the splicing mutation (IVS32-12A > G) reported in a Japanese patient. Patient 2 of Japanese origin was found to be compound heterozygous for a novel nonsense mutation, Y1148X, and the splicing mutation (IVS14+1G > T) that we had described previously. To determine whether splicing mutations occurred independently, we performed intense AGL haplotype analysis using 21 intragenic polymorphic markers plus a novel polymorphism IVS32-97 A/G in the vicinity of the IVS32 splicing mutation. Patient 1 of Chinese origin and the Japanese patient homozygous for the IVS32-12A > G were found to have different haplotypes, indicating the IVS32-12A > G mutation to be a recurrent mutation. This is the first recurrent mutation established by intense haplotyping in the AGL gene.

Adult↗

PubMed2002

Double deletions and missense mutations in the first nucleotide-binding fold of the ATP-binding cassette transporter A1 ( ABCA1) gene in Japanese patients with Tangier disease.

Tangier disease (TD) is a rare autosomal recessive disease characterized by plasma high-density lipoprotein deficiency caused by an ATP-binding cassette transporter A1 ( ABCA1) gene mutation. We describe three different mutations in Japanese patients with TD. The first patient was homozygous for double deletions of 1221 bp between intron 12 and 14 and 19.9 kb between intron 16 and 31. The breakpoint sequence analyses suggest that it is a simultaneous event caused by double-loop formation through multiple Alu. The second patient was homozygous for a novel mutation of A3198C in exon 19, resulting in Asn935His. The third patient was homozygous for A3199G of exon 19 that leads to Asn935Ser, which is the same mutation found in German and Spanish families. Both Asn mutations involved Walker A motif of the first nucleotide-binding fold.

ATP Binding Cassette Transporter 1↗

PubMed2002

Characterization of a novel missense mutation E637K in the pore-S6 loop of HERG in a patient with long QT syndrome.

OBJECTIVE: In a 32-year-old woman with marked QT prolongation (QTc=0.61 s) and repeated episodes of syncope, we identified a single pertinent base substitution (G to A at 1909) in HERG by genetic analysis. This novel missense mutation is predicted to cause an amino acid substitution of lysine for glutamic acid at position 637 (E637K) in the pore-S6 loop. Therefore, we investigated the role of a glutamic acid at the vicinity of the pore in HERG channels by mutating it to a lysine. METHODS: We characterized the electrophysiological properties of the E637K mutation using a Xenopus oocyte heterologous expression system. RESULTS: Injection of the E637K mutant cRNA alone into Xenopus oocytes did not result in any expression of detectable currents. Coexpression of wild-type (WT) and E637K (E637K/WT) elicited only about 30% of the control peak tail current that was expected from expression of WT alone. Kinetic analyses revealed that E637K/WT decelerated the rate of channel activation and enhanced steady-state inactivation. Furthermore, the reversal potentials at low concentrations of K+ showed a positive shift in oocytes injected with E637K/WT compared with WT alone. CONCLUSIONS: These results indicated that the E637K mutation causes apparent dominant negative suppression of WT HERG channel function and suggest that E637 at the Pore-S6 is a crucial component of the activation and inactivation gate of HERG channels.

Adult↗

PubMed2002

A randomized, double-blind trial comparing the efficacy and safety of pitavastatin versus pravastatin in patients with primary hypercholesterolemia.

Pitavastatin (p-INN) is a novel and fully synthetic 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor, with a cholesterol-lowering action stronger than that of other statins currently in use. A 12-week, multi-center, randomized, double-blind, controlled study was conducted to confirm the efficacy and safety of pitavastatin compared with pravastatin, an agent for using to reduce low density lipoprotein cholesterol (LDL-C) in hypercholesterolemic patients. Patients were recruited at 43 institutes in Japan. Following more than 4 weeks run-in period, 240 patients were randomized to receive 2 mg of pitavastatin or 10 mg of pravastatin daily. At 12 weeks post-randomization, the pitavastatin group showed significantly lower LDL-C levels by -37.6% from baseline compared with -18.4% in the pravastatin group (P<0.05). Pitavastatin also significantly lowered total cholesterol (TC) by -28.2% compared with -14.0% of pravastatin (P<0.05). The LDL-C target level of <140 mg/dl was attained in 75% of the patients treated with pitavastatin, compared with 36% of those in the pravastatin group (P<0.05). Pitavastatin also significantly reduced triglycerides (TG), apo B, C-II and C-III, compared with pravastatin, and increased HDL-C, apo A-I and A-II, to the same extent of pravastatin. Safety was assessed by monitoring adverse events and measuring clinical laboratory parameters. The adverse event profile was similar for both treatment groups and neither treatment caused clinically relevant laboratory abnormalities. These results indicated that pitavastatin was more effective than pravastatin, and both drugs were well-tolerated in the treatment of hypercholesterolemia.

Adult↗

PubMed2002

Long-term treatment with pitavastatin (NK-104), a new HMG-CoA reductase inhibitor, of patients with heterozygous familial hypercholesterolemia.

The clinical efficacy and safety of pitavastatin (NK-104), a novel HMG-CoA reductase inhibitor, during long-term treatment, were examined in 25 patients (male/female=11/14, mean age=53+/-13 (mean+/-SD) years) with heterozygous familial hypercholesterolemia (FH). After a period on placebo of >4 weeks, 2 mg/day of pitavastatin was administered for 8 weeks, and the dose was increased to 4 mg/day for up to 104 weeks. Total cholesterol (TC) decreased by 31% from the initial value of 340+/-57 to 237+/-40 mg/dl (P<0.0001) at week 8. During treatment with the higher dose, TC decreased even further to 212+/-35 mg/dl at week 12; it decreased by 37% from the initial value (P<0.0001). Similarly, the baseline low-density lipoprotein (LDL)-cholesterol (LDL-C) decreased by 41% at week 8, and by 49% at week 12, from 267+/-61 mg/dl at baseline. These findings indicate a dose-dependent effect of the drug on TC and LDL-C concentrations. To examine whether the levels of circulating matrix metalloproteinases (MMPs) and their endogenous inhibitors (tissue inhibitors of metalloproteinases: TIMPs) are altered during lipid-lowering therapy, we also measured their plasma levels. The mean levels of MMP-2 and -3 were significantly increased. No significant alteration was found in MMP-9, TIMP-1 and -2 levels. As for the safety of pitavastatin, adverse reactions were observed in one case (4%) of subjective and objective symptoms. The effects of pitavastatin on TC and LDL-C were stable during long treatment of patients with heterozygous FH.

Adult↗

PubMed2002

Effects of serum B vitamins on elevated plasma homocysteine levels associated with the mutation of methylenetetrahydrofolate reductase gene in Japanese.

High plasma homocysteine, a risk factor for atherosclerosis, is frequently caused by a common mutation in the gene for the enzyme, 5,10-methylenetetrahydrofolate reductase (MTHFR), C677T (alanine to valine substitution) or low intake of B vitamins that affect the remethylation or transsulfuration pathways in homocysteine metabolism. However, the interaction of the C677T mutation and B vitamins other than folate has not been well elucidated. We conducted a cross-sectional survey of 324 men and 641 women who participated in a 1996 health examination under a hypothesis that high nutritional status of folate, vitamin B12 and vitamin B6 expressed as high serum levels, may compensate for the hyperhomocysteinemia associated with homozygosity for the C677T mutation, but not for having the mutation per se. Age-adjusted plasma homocysteine levels were higher for both men and women with the homozygous genotype for the mutation than those who were heterozygous or had no mutation. Elevated homocysteine levels in homozygous genotype was attenuated among persons with higher serum levels of vitamin B12 and folate, but not vitamin B6, and among persons with the combination of lower folate and higher vitamin B12 and of higher folate and higher vitamin B12, split by the median. These findings suggest that elevated homocysteine levels among Japanese with the homozygous genotype for the MTHFR gene mutation can be modified efficiently by dietary supplement of vitamin B12 as well as folate.

Adult↗

PubMed2002

Molecular genetic analysis of familial hypercholesterolemia: spectrum and regional difference of LDL receptor gene mutations in Japanese population.

To determine the molecular basis of familial hypercholesterolemia (FH) in Japan, 200 unrelated patients with clinically diagnosed heterozygous FH were screened for mutations in coding and promoter region of the low density lipoprotein (LDL) receptor gene using denaturing gradient-gel electrophoresis (DGGE), DNA sequencing and Southern blotting analysis. About 37 different mutations in the LDL receptor gene were identified in 125 (62.5%) of the patients, 22 of these mutations have not been described before. The most common mutations were K790X (19.5%), P664L (6.0%), FH-Tonami-1 (6.0%), IVS15-3C>A (5.5%) and FH-Tonami-2 (4.5%), whereas the other mutations were rare. No apolipoprotein B (apoB) mutations responsible for familial ligand-defective apoB-100 (FDB) were identified. Polymorphisms of apolipoprotein E (apoE) and scavenger receptor class B type I (SR-BI) were observed to have minor effects on the lipid and lipoprotein profile. In 75 (32.5%) of the FH patients, LDL receptor gene mutations could not be identified. These patients had significantly lower total cholesterol (7.71+/-1.64 vs. 8.68+/-1.47 mmol/l, P<0.001) and LDL-cholesterol (6.02+/-1.51 vs. 6.87+/-1.47 mmol/l, P<0.001) in plasma, also a lower incidence of coronary heart disease (CHD) (22 vs. 29%, P=0.05) compared with patients with a LDL receptor gene mutation, suggesting that besides LDL receptor, defect of other genes involved in LDL metabolism may be a cause of FH with a milder phenotypic expression in Japanese population.

Adult↗

PubMed2002

19-Noraldosterone in pregnancy-induced hypertension.

Pregnancy-induced hypertension (PIH) is a frequent cause of maternal and neonatal morbidity and mortality. 19-Noraldosterone, which was shown to be synthesized in the human adrenal gland, exhibits potent mineralocorticoid and hypertensive activity. To examine the role of mineralocorticoids in the pathophysiology of PIH, we studied urinary 19-noraldosterone, tetrahydroaldosterone, free cortisol, and cortisone concentrations and mineralocorticoid receptor levels in peripheral blood mononuclear leukocytes, from 17 women with PIH and 16 normal pregnant women as controls. Sequence analysis of the mineralocorticoid receptor gene in PIH patients was also done. The 24-h urinary excretion of 19-noraldosterone was significantly lower in PIH (120 +/- 38 pmol/day) than in controls (358 +/- 55 pmol/day) (P < 0.05). Urinary tetrahydroaldosterone was also decreased in PIH compared with controls. Ratios of urinary free cortisol to cortisone (a measure of 11beta-hydroxysteroid dehydrogenase 2 activity) did not differ significantly between groups. Mineralocorticoid receptor density was significantly (P < 0.05) decreased in the PIH group (133 +/- 15 binding sites/cell) compared with controls (255 +/- 21 binding sites/cell). No mutations were found in the coding region of the mineralocorticoid receptor gene in PIH. These results suggest that circulating aldosterone, 19-noraldosterone, and renal 11beta-hydroxysteroid dehydrogenase2 do not contribute to the pathogenesis of PIH. Regulatory factors that cause the down-regulation of the mineralocorticoid receptor in PIH should be clarified.

Adolescent↗

PubMed2002

Syntheses of fused heterocyclic compounds and their inhibitory activities for squalene synthase.

A variety of fused heterocyclic compounds (2-11) were synthesized as a modification of the lead compound 1a and evaluated for their inhibition of squalene synthase. 4,1-Benzothiazepine derivative 2, 1,4-benzodiazepine derivative 6, 1,3-benzodiazepine derivative 7, 1-benzazepine derivative 9, and 4,1-benzoxazocine derivative 10 potently inhibited squalene synthase activity, whereas the 4,1-benzoxazepine derivatives 1 was the most potent inhibitor. 4,1-Benzothiazepine S-oxide derivative 4, 1,4-benzodiazepine derivative 5, 1,3,4-benzotriazepine derivative 8, and 1,2,3,4-tetrahydroquinoline derivative 11 were found to be weakly active. Comparison of the X-ray structures of these compounds (1a, 2, 4, 5, 7 and 10) suggests that orientation of the 5- (or 6)-phenyl group is important for activity.

Animals↗

PubMed2002

Novel 4,1-benzoxazepine derivatives with potent squalene synthase inhibitory activities.

A series of (3,5-trans)-2-oxo-5-phenyl-1,2,3,5-tetrahydro-4,1-benzoxazepine derivatives were synthesized and evaluated for squalene synthase inhibitory and cholesterol biosynthesis inhibitory activities. Through modification of substituents of the lead compounds 1a and 1b, it was found that 4,1-benzoxazepine-3-acetic acid derivatives with isobutyl and neopentyl groups at the 1-position, the chloro atom at the 7-position, and the chloro and methoxy groups at the 2'-position on the 5-phenyl ring, had potent squalene synthase inhibitory activity. Among such compounds, the 5-(2,3-dimethoxyphenyl) derivative 2t exhibited potent inhibition of cholesterol biosynthesis in HepG2 cells. As a result of optical resolution study of 2t, the absolute stereochemistry required for inhibitory activity was determined to be 3R,5S. In vivo study showed that the sodium salt of (3R,5S)-7-chloro-5-(2,3-dimethoxyphenyl)-1-neopentyl-2-oxo-1,2,3,5-tetrahydro-4,1-benzoxazepine-3-acetic acid 20 effectively reduced plasma cholesterol in marmosets.

Administration, Oral↗

PubMed2002

Cholesteryl ester transfer protein inhibitor (JTT-705) and the development of atherosclerosis in rabbits with severe hypercholesterolaemia.

Cholesteryl ester transfer protein (CETP) is a major determinant of plasma levels of high-density lipoprotein-cholesterol (HDL-C) in humans. The anti-atherogenic effect of lowering CETP levels is dependent not only on HDL-C levels but also on a metabolic background of increased low-density lipoprotein or very-low-density lipoprotein. Here we investigated the effects of JTT-705, a chemical inhibitor of CETP, on the development of atherosclerosis in Japanese white rabbits fed on a high cholesterol diet. After 4 weeks on a diet of 0.25% cholesterol-containing chow, 100 mg/kg (low dose) or 300 mg/kg (high dose) JTT-705 was given, and the animals were monitored at weeks 0, 4, 8 and 12. Aortic atherosclerotic lesions were determined at the end of this period. JTT-705 induced a significant increase in HDL-C in the high-dose group [from 21+/-3 to 50+/-7 mg/dl (mean+/-S.E.M.); P <0.0001] compared with the control group (from 21+/-2 to 27+/-2 mg/dl). The atheromatous area was 60+/-9% in the high-dose group and 58+/-9% in the control group. Moreover, correlation analysis showed that triacylglycerol and non-HDL-C levels had a direct relationship with the development of atherosclerosis, but CETP activity and HDL-C levels did not. Thus the CETP inhibitor JTT-705 alone did not have an anti-atherogenic effect in our rabbit model, of severe hypercholesterolaemia suggesting a relatively minor effect of HDL-elevating therapy as compared with decreases in non-HDL-C (or triacylglycerol) levels in patients with severe hypercholesterolaemia, such as familial hypercholesterolaemia.

Amides↗

PubMed2002

An LMNA variant is associated with dyslipidemia and insulin resistance in the Japanese.

Nuclear lamins A and C are encoded by LMNA and are present in terminally differentiated cells. Rare mutations in LMNA were shown to cause familial partial lipodystrophy, a syndrome characterized by regional loss of adipose tissue, glucose intolerance, and dyslipidemia, making LMNA a candidate gene for insulin-resistant diabetes. The aim of this study was to investigate whether genetic variation in LMNA can influence the risk of type 2 diabetes in a Japanese cohort. First, we performed mutational screening of LMNA by polymerase chain reaction-single-strand conformation polymorphism (PCR-SSCP) and sequence analysis in 8 insulin-resistant males with acanthosis nigricans who were not lipodystrophic. One known single nucleotide polymorphism, 1908C/T, was found in exon 10. We subsequently screened samples of 171 nondiabetic and 164 type 2 diabetic male subjects for the presence of the 1908C/T polymorphism by PCR-restriction fragment length polymorphism (RFLP). The frequency of subjects with the 1908T allele tended to be higher in the diabetic group than in the nondiabetic group; however, the difference was not significant (43.9% v 32.2%) (P =.084). Carriers of the 1908T allele, both among diabetics and nondiabetics, showed significantly higher fasting insulin, triglycerides (TG), total cholesterol (TC), and lower high-density lipoprotein-cholesterol (HDL-C) levels than those of the 1908C/C subjects. These results suggest the LMNA 1908C/T single nucleotide polymorphism (SNP) is not associated with the prevalence of type 2 diabetes, although it may be a factor predisposing to insulin resistance and dyslipidemia in some Japanese.

Adult↗

PubMed2002

Clinical efficacy of pitavastatin, a new 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor, in patients with hyperlipidemia. Dose-finding study using the double-blind, three-group parallel comparison.

Pitavastatin (CAS 147526-32-7, NK-104), the first totally synthetic 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor discovered in Japan, was examined. Pitavastatin significantly decreased the serum levels of total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) at doses of 1 mg/day or more, and significant dose-dependence of the effect of this drug was observed within the dose range from 1 mg/day to 4 mg/day. It also significantly decreased the serum levels of triglycerides (TG) within this dose range. There was no dose-dependence of the incidence of adverse reactions to pitavastatin.

Adult↗

PubMed2002

Chronologic electrocardiographic changes in patients with hypertrophic cardiomyopathy associated with cardiac troponin 1 mutation.

BACKGROUND: Deletion of lysine 183 (K183del) in the cardiac troponin I (cTnI) gene is one of the mutations that causes hypertrophic cardiomyopathy (HCM). However, the phenotypic expression of this mutation has not been well established. METHODS AND RESULTS: We analyzed 10 probands with HCM associated with a K183del in the cTnI gene, as well as their family members. Forty-seven of these 80 subjects were found to be carriers and 33 were noncarriers. In the carrier subjects, electrocardiogram (ECG) abnormalities were initially noted during the early teenage years preceding echocardiographic abnormalities. Abnormal Q waves were found first and most frequently compared with other ECG abnormalities. Abnormal Q waves were frequently observed in leads II, III, aVF, V5, and V6 in teenage patients, whereas they were observed in many leads in patients >20 years old. The youngest of the 11 patients who had sudden cardiac death among studied pedigrees was a 14-year-old boy. CONCLUSIONS: These results suggest that the first phenotypic manifestation in patients with HCM associated with a K183del mutation in the cTnI gene is abnormal Q waves in leads II, III, aVF, V5, and V6 during the early teenage years. To prevent sudden death in family members of patients with this mutation, it may be necessary to genetically diagnose it before age 10 years and to pay careful attention to any development of abnormal Q waves.

Adolescent↗