• Molecules and Cells
• /
• v.20 no.3
• /
• pp.385-391
• /
• 2005

As a first step towards identifying genes involving in the signal transduction pathways mediating rice blast resistance, we isolated 3 mutants lines that showed enhanced susceptibility to rice blast KJ105 (91-033) from a T-DNA insertion library of the japonica rice cultivar, Hwayeong. Since none of the susceptible phenotypes co-segregated with the T-DNA insertion we adapted a map-based cloning strategy to isolate the gene(s) responsible for the enhanced susceptibility of the Hwayeong mutants. A genetic mapping population was produced by crossing the resistant wild type Hwayeong with the susceptible cultivar, Nagdong. Chi-square analysis of the $F_2$ segregating population indicated that resistance in Hwayeong was controlled by a single major gene that we tentatively named Pi-hy. Randomly selected susceptible plants in the $F_2$ population were used to build an initial map of Pi-hy. The SSLP marker RM2265 on chromosome 2 was closely linked to resistance. High resolution mapping using 105 $F_2$ plants revealed that the resistance gene was tightly linked, or identical, to Pib, a resistance gene with a nucleotide binding sequence and leucine-rich repeats (NB-LRR) previously isolated. Sequence analysis of the Pib locus amplified from three susceptible mutants revealed lesions within this gene, demonstrating that the Pi-hy gene is Pib. The Pib mutations in 1D-22-10-13, 1D-54-16-8, and 1C-143-16-1 were, respectively, a missense mutation in the conserved NB domain 3, a nonsense mutation in the 5th LRR, and a nonsense mutation in the C terminus following the LRRs that causes a small deletion of the C terminus. These findings provide evidence that NB domain 3 and the C terminus are required for full activity of the plant R gene. They also suggest that alterations of the resistance gene can cause major differences in pathogen specificity by affecting interactions with an avirulence factor.

• Clinical and Experimental Pediatrics
• /
• v.57 no.5
• /
• pp.240-244
• /
• 2014

Pseudohypoparathyroidism type Ia (PHP Ia) is a disorder characterized by multiform hormonal resistance including parathyroid hormone (PTH) resistance and Albright hereditary osteodystrophy (AHO). It is caused by heterozygous inactivating mutations within the Gs alpha-encoding GNAS exons. A 9-year-old boy presented with clinical and laboratory abnormalities including hypocalcemia, hyperphosphatemia, PTH resistance, multihormone resistance and AHO (round face, short stature, obesity, brachydactyly and osteoma cutis) which were typical of PHP Ia. He had a history of repeated convulsive episodes that started from the age of 2 months. A cranial computed tomography scan showed bilateral calcifications in the basal ganglia and his intelligence quotient testing indicated mild mental retardation. Family history revealed that the patient's maternal relatives, including his grandmother and 2 of his mother's siblings, had features suggestive of AHO. Sequencing of the GNAS gene of the patient identified a heterozygous nonsense mutation within exon 11 (c.637 C>T). The C>T transversion results in an amino acid substitution from Gln to stop codon at codon 213 ($p.Gln213^*$). To our knowledge, this is a novel mutation in GNAS.

• Biomolecules & Therapeutics
• /
• v.27 no.6
• /
• pp.577-583
• /
• 2019

Human cytochrome P450 2C9 is a highly polymorphic enzyme that is required for drug and xenobiotic metabolism. Here, we studied eleven P450 2C9 genetic variants-including three novel variants F69S, L310V, and Q324X-that were clinically identified in Korean patients. P450 2C9 variant enzymes were expressed in Escherichia coli and their bicistronic membrane fractions were prepared The CO-binding spectra were obtained for nine enzyme variants, indicating P450 holoenzymes, but not for the M02 (L90P) variant. The M11 (Q324X) variant could not be expressed due to an early nonsense mutation. LC-MS/MS analysis was performed to measure the catalytic activities of the P450 2C9 variants, using diclofenac as a substrate. Steady-state kinetic analysis revealed that the catalytic efficiency of all nine P450 2C9 variants was lower than that of the wild type P450 2C9 enzyme. The M05 (R150L) and M06 (P279T) variants showed high $k_{cat}$ values; however, their $K_m$ values were also high. As the M01 (F69S), M03 (R124Q), M04 (R125H), M08 (I359L), M09 (I359T), and M10 (A477T) variants exhibited higher $K_m$ and lower $k_{cat}$ values than that of the wild type enzyme, their catalytic efficiency decreased by approximately 50-fold compared to the wild type enzyme. Furthermore, the novel variant M07 (L310V) showed lower $k_{cat}$ and $K_m$ values than the wild type enzyme, which resulted in its decreased (80%) catalytic efficiency. The X-ray crystal structure of P450 2C9 revealed the presence of mutations in the residues surrounding the substrate-binding cavity. Functional characterization of these genetic variants can help understand the pharmacogenetic outcomes.

• Journal of Preventive Medicine and Public Health
• /
• v.33 no.3
• /
• pp.323-333
• /
• 2000

Objectives : Chronic HBsAg carriers are the principal source of infection for other susceptible people, and are themselves at high risk of developing serious liver diseases. In Korea, it has been estimated that 65-75% of the HBsAg positives remained as persistent carriers. Additionally, familial clustering of MBV infection has frequently been observed among carriers. Some would become progressive, chronic hepatitis patients, and others would not. The aim of this study was to evaluate the association between various factors, such as the duration of infection, type of virus, mutation of precore/core region in HBV, major histocompatibility class-I, and developing chronic liver diseases among familial HBV carriers. Methods : Chronic carrier status was identified by repeated serological tests for HBsAg at intervals of six months or more. A familial chronic carrier was defined when the disease was observed in a family member over two generations. Two families were recruited, among which a total of 20 chronic HBsAg carriers(11 carriers in No.1, and 9 in No.2 family) were identified. Data on the general characteristics and liver disease status were collected. Identification of the HBV-DNA was successful only for 13 subjects among the 20 carriers. Analysis of viral DNA in terms of subtype, pre-core and core region mutations was carried out. The type of major histocompatibility class-1 for the 13 subjects was also analysed. Results & Conclusions : Seven of 10 chronic HBV carriers of the 1st generation and one of 10 of the 2nd generation were clinical patients with chronic hepatitis, the others, three of the 1 st and nine of the 2nd generation, were asymptomatic carriers. This data indicates that the duration of HBV carriage is one of the major factors for disease severity. The subtype of HBsAg analysed using MBV-DNA identified in 13 carriers were adr, and the pattern of precore nonsense mutation in HBV-DNA was identical among family members, which meads that the same virus strains were transmitted between the family members. The association between the precore or core mutations in HBV-DNA and the disease severity was not observed. While it was suggested that a specific type of MHC class-I may be related to disease progression.

• Clinical and Experimental Pediatrics
• /
• v.51 no.9
• /
• pp.964-970
• /
• 2008

Purpose : Methylmalonic aciduria (MMA) and propionic aciduria (PA) are inborn errors in the catabolism of branched-chain amino acids. The study was undertaken to investigate the genotypes and clinical features of Korean patients with MMA and PA. Methods : This study examined 12 patients with MMA and eight with PA. We analyzed various clinical features, laboratory findings, treatments, and neuro-developmental outcomes. Diagnoses were based on the presence of characteristic compounds detected by amino acid analysis in serum and organic acid analysis in urine. Mutation analysis was performed in the genes of MUT, MMAA, MMAB, and MMACHC for MMA and PCCA and PCCB for PA. Results : Among the 20 patients, six patients were diagnosed before one month of age and nine patients were diagnosed after the newborn period. Five patients were diagnosed via a neonatal screening test. Patients with early-onset forms had more severe illness at presentation and generally poor outcomes. A favorable outcome was obtained in 55% patients; most of them were of a late-onset type or diagnosed by neonatal mass screening test without symptoms. Genotypes were confirmed in all patients with MMA. We detected 11 different mutations by MUT gene analysis in 10 patients, and three different mutations in MMACHC genes in two patients. PCCA and PCCB gene mutations were identified in 14 of the 16 alleles, in eight patients with PA. Conclusion : Organic aciduria is a fatal disease; however, better outcomes are expected whenever early diagnosis and prompt management are made possible. Mutation analysis is useful for confirming diagnoses and planning management strategies.

• Journal of The Korean Society of Inherited Metabolic disease
• /
• v.17 no.3
• /
• pp.85-91
• /
• 2017

Purpose: The aim of this study was to describe the clinical and biochemical features as well as the molecular analysis of a newly diagnosed illustrative case with ML II and to analyze the clinical features of 11 Korean patients with ML II/III. Method: Including a newly diagnosed patient, total 11 patients in 10 families were diagnosed as ML II (n=7) or ML III (n=4) were enrolled in the study. A diagnosis of ML II or III was made by demonstrating increased lysosomal enzyme activities in the plasma and sequence analysis of GNPTAB with characteristic clinical features. Result: A illustrative case of ML II patient was a 17 month-old boy showing characteristic facial appearance, multiple joint contractures with cardiac involvements. The enzyme assay showed increased lysosomal enzyme activities in the plasma. We identified compound heterozygous mutations in GNPTAB sequence analysis, including a frameshift (c.3428dupA [pAsn1143Lysfs*3]) and a nonsense variant c.673C>T (p.Gln225*). In total 11 patients with ML II/III, the patients with ML II showed severe growth retardation (height standard deviation score -3.2 [${\pm}1.5$]), compare to patients with ML III. Furthermore, patients with ML II patients had serious cardiac problem (n=4), hepatomegaly (n=3) and underwent tracheostomy (n=3) with further respiratory support due to respiratory distress. To improve osteoporosis and bone pain, all patients with ML III and four of 7 patients with ML II treated with intravenous pamidronate. Conclusion: Here we showed a newly diagnosed case of ML II and clinical features of 11 Korean patients with ML II or III. These data could be helpful for further diagnosis of mucolipidosis, a rare inherited metabolic disease, in Korea.