• Journal of The Korean Society of Inherited Metabolic disease
• /
• v.4 no.1
• /
• pp.5-12
• /
• 2004

Purpose Phenylketonuria is an inborn error of metabolism, which is inherited as an autosomal recessive trait. PKU is resulting from deficiency of phenylalanine hydroxylase. PAH gene spans about 90 kb on chromosome 12q and comprises 13 exons. In order to define the genetic basis of PKU and the frequencies and distribution of PAH mutations in the Korean population, we analyzed PAH gene in independent 80 patients with PKU. Methods All 13 exons including exon-intron boundaries and 2 kb of 5' upstream region of the PAH gene were analyzed by PCR-direct sequencing methods. Results PAH gene analysis revealed 39 different mutations including 10 novel mutations. The novel mutations consisted of 9 missense mutations (P69S, G103S, N207D, T278S, P281A, L293M, G332V, S391I and A447P) and a novel splice site variant (IVS10-3C>G). R243Q, IVS4-1G>A, and E6-96A>G were the most relevant mutations and they accounted in the whole for 38% of the mutant alleles identified in this study. We also observed that. $BH_4$ responsibility was. associated with genotype of R241C, R53H and R408Q. Conc1ustion Our present study with 80 participants extends the previous results to more comprehensive understanding of PAH allele distribution and frequency in Koreans. Although Korean mutation profile of PAH is similar to those of the nearest oriental populations (Japanese, Chinese, and Taiwanese), several different characteristic features are revealed. The characterization of the genotype-phenotype relationship was also performed. Our data would be very useful information for diagnosis, genetic counseling and planning of dietary and therapeutic strategies in Korean PAH patients.

• Asian Pacific Journal of Cancer Prevention
• /
• v.17 no.3
• /
• pp.965-971
• /
• 2016

Aims: To investigate the distribution of epidermal growth factor receptor (EGFR) mutations, and explore any relationships with clinical characteristics in non-small-cell lung carcinoma (NSCLC) patients. Materials and Methods: EGFR mutations were assessed by ADx-ARMS in 261 NSCLC patients from West China Hospital of Sichuan University. Relationships between EGFR mutation and clinical characteristics were analyzed by SPSS. Results: The EGFR mutation rate was 48.7% (127/261), 19-del and L858R mutations occurred predominantly, accounting for 33.1% and 40.9%, respectively, in mutated cases. Moreover, 10.2% patients were found to carry double mutations. EGFR mutations occurred more frequently in women (57.5%) than in men (41.8%) (P=0.01), and were more frequent in non-smokers (61.2%) than in former or current smokers (31.2%) (P<0.00). In addition, they were more common in adenocarcinomas (52.8%) and adenosquamous carcinomas (42.8%) than in squamous cell carcinomas (14.8%) (p<0.00). However, only smoking history and pathological types, rather than gender, proved to be associated with EGFR mutations on multivariate logistic regression analysis. No significant differences in pathological stage and metastasis status were found between EGFR wild-type and mutated cases, although EGFR mutation type was related to pathological type (p=0.00) - 19-del, L858R and other mutation types respectively occurred in 34.2%, 42.5% and 23.3% of adenocarcinomas, but in 14.3%, 0% and 85.7% of non-adenocarcinomas. Conclusions: The EGFR mutation rate was 48.7% in NSCLCs in Southwest China, so that nearly 40% patients might benefit from targeted therapies. Smoking status and pathological types were independent predictors of EGFR mutation, while EGFR mutation type was related to only pathological type, rather than smoking status.

• Asian Pacific Journal of Cancer Prevention
• /
• v.14 no.7
• /
• pp.4279-4282
• /
• 2013

Background: The activation and inactivation of receptor tyrosine kinases are tightly regulated to ensure faithful replication of cells. After having transduced extracellular growth activating signals, activated EGFR is subjected to downregulation either by clathrin mediated endocytosis or c-Cbl mediated proteasome degradation depending on the ligand concentration. c-Cbl is an ubiquitin ligase which requires a phosphorylated tyrosine residue at position 1045 in the cytoplasmic domain of EGFR to interact and add ubiquitin molecules. While activating mutations in exons 19 and 21 have been associated with the development of several cancers, the status of mutations at tyrosine 1045 coding exon 27 of EGFR remain to be investigated. Consistently, defective phosphorylation at 1045 has been associated with sustained phosphorylation of EGFR in non-small lung carcinomas. Hence in the present study we investigated the genetic status of the tyrosine 1045 coding site within exon 27 of EGFR gene to explore for possible occurrence of mutations in this region, especially since no studies have addressed this issue so far. Materials and Methods: Tumor chromosomal DNA isolated from thirty five surgically excised oral squamous cell carcinoma tissues was subjected to PCR amplification with intronic primers flanking the tyrosine 1045 coding exon 27 of EGFR gene. The PCR amplicons were subsequently subjected to direct sequencing to elucidate the mutation status. Results: Sequence analysis identified no mutations in the tyrosine 1045 codon of EGFR in any of the thirty five samples that were analyzed. Conclusions: The lack of identification of mutation in the tyrosine 1045 codon of EGFR suggests that mutations in this region may be relatively rare in oral squamous cell carcinomas. To the best of our knowledge, this study is the first to have explored the genetic status of exon 27 of EGFR in oral squamous cell carcinoma tissue samples.

• Childhood Kidney Diseases
• /
• v.22 no.2
• /
• pp.37-41
• /
• 2018

Purpose: Familial renal glucosuria (FRG, OMIM #233100) is a rare but relatively benign genetic condition characterized by persistent isolated glucosuria with a normal blood glucose level. We report three additional SLC5A2 mutations and examine their phenotypic and genetic characteristics in a Korean FRG cohort. We also reviewed the literature and summarized the genotypes of all Korean patients with FRG. Methods: A genetic analysis was conducted by directly sequencing all 14 exons of the SLC5A2 gene and their flanking regions in six unrelated Korean children with FRG and their family members. Novel non-synonymous single-nucleotide polymorphisms were identified and compared with known mutations that are repeatedly detected in the Korean population. Results: We found two novel mutations [c.274G>A (G92S) and c.1168C>T (L390F)] and one known [c.1382G>A (S461N)] mutation in each family and one recurrent mutation [c.1346G>A (G449D) (rs768392222)] in two pedigrees. The recurrent G449D was predicted to be "possibly damaging," with a score of 0.883 in Polyphen-2, while G92S, L390F, and S461N were predicted to be "probably damaging," with scores of 1.000, 0.999, and 0.996, respectively. Conclusions: Two novel, one previously reported, and one recurrent mutation were identified in six Korean FRG pedigrees as causative mutations of renal glucosuria. Sequence variations in the SLC5A2 gene were frequently detected in children with persistent isolated glucosuria. A long-term follow-up of this FRG cohort is needed to understand how these specific SGLT2 mutations impair kidney function and energy homeostasis.

• Journal of Genetic Medicine
• /
• v.13 no.1
• /
• pp.31-35
• /
• 2016

Antley-Bixler syndrome (ABS) is a rare form of syndromic craniosynostosis with additional systemic synostosis, including radiohumeral or radioulnar synostosis. Another characteristic feature of ABS is mid-facial hypoplasia that leads to airway narrowing after birth. ABS is associated with mutations in the FGFR2 and POR genes. Patients with POR mutations present with either skeletal manifestations or congenital adrenal hyperplasia with ambiguous genitalia. We report here two cases of ABS caused by mutations in FGFR2 and POR. Although the patients had craniosynostosis and radiohumeral synostosis in common and cranioplasty was performed in both cases, the male with POR mutations showed an elevated level of $17{\alpha}$-hydroxyprogesterone during newborn screening and was diagnosed with congenital adrenal hyperplasia by adrenocorticotropic hormone stimulation. This patient has been treated with hydrocortisone and fludrocortisone. He had no ambiguous genitalia but had bilateral cryptorchidism. On the other hand, the female with the FGFR2 mutation showed severe clinical manifestations: upper airway narrowing leading to tracheostomy, kyphosis of the cervical spine, and coccyx deformity. ABS shows locus heterogeneity, and mutations in two different genes can cause similar craniofacial and skeletal phenotypes. Because the long-term outcomes and inheritance patterns of the disease differ markedly, depending on the causative mutation, early molecular genetic testing is helpful.

• BMB Reports
• /
• v.37 no.2
• /
• pp.246-253
• /
• 2004

Constitutional RB1 gene mutations were studied in a series of 21 families with unilateral and bilateral retinoblastoma patients. Peripheral blood lymphocytes were analyzed by "exon by exon" PCR-heteroduplex and sequencing. Mutations were identified in 6 (29%) of the patients. One mutation corresponded to an intronic polymorphism in g.174351T > A. The other five mutations resulted C to T exonic transitions, four were CGA sequences (g.65386, g.150037 in two patients, and g.162237), creating stop codons and presumably truncated proteins. The fifth one was new and resulted in alanine to valine substitution (g.73774). Two patients had the same the germline truncated mutation (g.150037C > T), one with a familial bilateral early onset retinoblastoma and one with a sporadic unilateral late onset retinoblastoma. The later type has not been previously described. This finding is discussed in the genotype/phenotype correlation context. Additionally, a single nucleotide change was found in six studied samples, where a C to T homozygous transversion was identified in intron 26 (IVS26 + 28). It is worthy the non concordance of the nucleotide with the published sequence. This analysis proved to be a useful method for the detection of mutations in the RB1 gene, and contributed to the adequate genetic counseling to patients and relatives.

• Annals of Laboratory Medicine
• /
• v.38 no.6
• /
• pp.563-568
• /
• 2018

Background: Delamanid, bedaquiline, and linezolid have recently been approved for the treatment of multidrug- and extensively drug-resistant (MDR and XDR, respectively) tuberculosis (TB). To use these drugs effectively, drug susceptibility tests, including rapid molecular techniques, are required for accurate diagnosis and treatment. Furthermore, mutation analyses are needed to assess the potential for resistance. We evaluated the minimum inhibitory concentrations (MICs) of these three anti-TB drugs for Korean MDR and XDR clinical strains and mutations in genes related to resistance to these drugs. Methods: MICs were determined for delamanid, bedaquiline, and linezolid using a microdilution method. The PCR products of drug resistance-related genes from 420 clinical Mycobacterium tuberculosis strains were sequenced and aligned to those of M. tuberculosis H37Rv. Results: The overall MICs for delamanid, bedaquiline, and linezolid ranged from ${\leq}0.025$ to >1.6 mg/L, ${\leq}0.0312$ to >4 mg/L, and ${\leq}0.125$ to 1 mg/L, respectively. Numerous mutations were found in drug-susceptible and -resistant strains. We did not detect specific mutations associated with resistance to bedaquiline and linezolid. However, the Gly81Ser and Gly81Asp mutations were associated with resistance to delamanid. Conclusions: We determined the MICs of three anti-TB drugs for Korean MDR and XDR strains and identified various mutations in resistance-related genes. Further studies are needed to determine the genetic mechanisms underlying resistance to these drugs.

• Biomolecules & Therapeutics
• /
• v.30 no.1
• /
• pp.19-27
• /
• 2022

Epidermal growth factor receptor (EGFR) is a receptor tyrosine kinase widely expressed in many cancers such as non-small cell lung cancer (NSCLC), pancreatic cancer, breast cancer, and head and neck cancer. Mutations such as L858R in exon 21, exon 19 truncation (Del19), exon 20 insertions, and others are responsible for aberrant activation of EGFR in NSCLC. First-generation EGFR tyrosine kinase inhibitors (TKIs) such as gefitinib and erlotinib have clinical benefits for EGFR-sensitive (L858R and Del19) NSCLC patients. However, after 10-12 months of treatment with these inhibitors, a secondary T790M mutation at the gatekeeper position in the kinase domain of EGFR was identified, which limited the clinical benefits. Second-generation EGFR irreversible inhibitors (afatinib and dacomitinib) were developed to overcome this T790M mutation. However, their lack of selectivity toward wild-type EGFR compromised their clinical benefits due to serious adverse events. Recently developed third-generation irreversible EGFR TKIs (osimertinib and lazertinib) are selective toward driving mutations and the T790M mutation, while sparing wild-type EGFR activity. The latest studies have concluded that their efficacy was also compromised by additional acquired mutations, including C797S, the key residue cysteine that forms covalent bonds with irreversible inhibitors. Because second- and third-generation EGFR TKIs are irreversible inhibitors, they are not effective against C797S containing EGFR triple mutations (Del19/T790M/C797S and L858R/T790M/C797S). Therefore, there is an urgent unmet medical need to develop next-generation EGFR TKIs that selectively inhibit EGFR triple mutations via a non-irreversible mechanism.

• Genomics & Informatics
• /
• v.21 no.3
• /
• pp.30.1-30.13
• /
• 2023

Ephs belong to the largest family of receptor tyrosine kinase and are highly conserved both sequentially and structurally. The structural organization of Eph is similar to other receptor tyrosine kinases; constituting the extracellular ligand binding domain, a fibronectin domain followed by intracellular juxtamembrane kinase, and SAM domain. Eph binds to respective ephrin ligand, through the ligand binding domain and forms a tetrameric complex to activate the kinase domain. Eph-ephrin regulates many downstream pathways that lead to physiological events such as cell migration, proliferation, and growth. Therefore, considering the importance of Eph-ephrin class of protein in tumorigenesis, 7,620 clinically reported missense mutations belonging to the class of variables of unknown significance were retrieved from cBioPortal and evaluated for pathogenicity. Thirty-two mutations predicted to be pathogenic using SIFT, Polyphen-2, PROVEAN, SNPs&GO, PMut, iSTABLE, and PremPS in-silico tools were found located either in critical functional regions or encompassing interactions at the binding interface of Eph-ephrin. However, seven were reported in nonsmall cell lung cancer (NSCLC). Considering the relevance of receptor tyrosine kinases and Eph in NSCLC, these seven mutations were assessed for change in the folding pattern using molecular dynamic simulation. Structural alterations, stability, flexibility, compactness, and solvent-exposed area was observed in EphA3 Trp790Cys, EphA7 Leu749Phe, EphB1 Gly685Cys, EphB4 Val748Ala, and Ephrin A2 Trp112Cys. Hence, it can be concluded that the evaluated mutations have potential to alter the folding pattern and thus can be further validated by in-vitro, structural and in-vivo studies for clinical management.

• Asian Pacific Journal of Cancer Prevention
• /
• v.15 no.9
• /
• pp.3927-3932
• /
• 2014

Background: Epidermal growth factor receptor (EGFR) mutations and echinoderm microtubule associated protein like 4-anaplastic lymphoma kinase (EML4-ALK) define specific molecular subsets of lung adenocarcinomas with distinct clinical features. Our purpose was to analyze clinical features and prognostic value of EGFR gene mutations and the EML4-ALK fusion gene in lung adenocarcinoma. Patients and Methods: EGFR gene mutations and the EML4-ALK fusion gene were detected in 92 lung adenocarcinoma patients in China. Tumor marker levels before first treatment were measured by electrochemiluminescence immunoassay. Results: EGFR mutations were found in 40.2% (37/92) of lung adenocarcinoma patients, being identified at high frequencies in never-smokers (48.3% vs. 26.5% in smokers; P=0.040) and in patients with abnormal serum carcinoembryonic antigen (CEA) levels before the initial treatment (58.3% vs. 28.6%, P=0.004). Multivariate analysis revealed that a higher serum CEA level before the initial treatment was independently associated with EGFR gene mutations (95%CI: 1.476~11.343, P=0.007). We also identified 8 patients who harbored the EML4-ALK fusion gene (8.7%, 8/92). In concordance with previous reports, younger age was a clinical feature for these (P=0.008). Seven of the positive cases were never smokers, and no coexistence with EGFR mutation was discovered. In addition, the frequency of the EML4-ALK fusion gene among patients with a serum CEA concentration below 5ng/ml seemed to be higher than patients with a concentration over 5ng/ml (P=0.021). No significant difference was observed for time to progression and overall survival between EML4-ALK-positive group and EML4-ALK-negative group or between patients with and without an EGFR mutation. Conclusions: The serum CEA level before the initial treatment may be helpful in screening population for EGFR mutations or EML4-ALK fusion gene presence in lung adenocarcinoma patients.