Amino Acid Substitution In Exon Research Articles

P2.03b-034 Clinical Relevant Oncogenic Drivers in Advanced Adenocarcinoma Discloses New Therapeutic Targets in Negative EGFR/ALK/KRAS Patients: Topic: Biomarkers

The mutation profile in the Brazilian population with advanced lung adenocarcinoma remains largely unexplored and also their relationship to many other genes. Next Generation Sequencing(NGS) allows higher sensitivity and multiplexing for several genes for translational research. 80 lung adenocarcinoma patients were collected. DNA concentration and quality was determined by Qubit2.0fluorometer and Agilent2100Bioanalyzer. Genomic libraries were constructed using the TruSeq®Custom Amplicon v1.5) comprising 764 amplicons of 38genes on the Illumina-MiSeq®sequencing plataform. The 7362 genetic mutation were observed with 78% of single-nuclotide variants (SNVs) and 22% insertions and deletions. The majority of the SNVs were located in inter-genic regions or introns. EGFR were mutated in 21 (6%) of patients with 19 (57%) of mean expression. The most frequent EGFR-mutation was exon 19deletions, followed by L858R amino acid substitution in exon 21. KRAS was mutated in 26 (4%) of patients. ALK rearrangement was detected in 6 patients (4.8%). The stop gained mutation was present in PIK3CA,TP53, AXL, EGFR, RAB25, CDH1, CD276 and TGFB1. The AXL receptor tyrosine kinase gene showed 11 missense-mutations, of which 7 are considered possibly damaging (Polyphen)/deleterious(SIFT)(74/79) and 14 intronSNVs(49/80). CD44 showed 50 variants, however most of them have an undetermined significance. The clustering analysis demonstrated that a select group of AXL-related gene alterations was highlighted (Fig 1). The results suggest that genomic variants in lung adenocarcinoma tissues are complex and show that NGS is an effective way to detect novel mutations in lung cancer. 58% of patients wild type by standard testing for EGFR/KRAS/ALK have genomic changes identifiable by CGP that suggest benefit from target therapy. The AXL and CD44 genes remain a relatively unexplored target, thus we intend to increase the available data for the true translational potential of target AXL and CD44 therapy in lung cancer. CGP used when standard molecular testing for adenocarcinoma is negative can reveal additional avenues of benefit from targeted therapy.

Mutational Profile and New IASLC/ATS/ERS Classification Provide Additional Prognostic Information about Lung Adenocarcinoma: A Study of 125 Patients from Brazil

Aim: To show additional prognostic information about the mutational profile and new International Association for the Study of Lung Cancer/American Thoracic Society/European Respiratory Society (IASLC/ATS/ERS) classification of adenocarcinoma (ADC) in patients without epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitor treatments. Methods: In human lung ADC patients (n = 125), including 24 lepidic, 67 acinar, 23 papillary, and 11 solid predominant subtypes, EGFR and KRAS were sequenced, and anaplastic lymphoma kinase (ALK) rearrangements were screened using fluorescence in situ hybridization (FISH). Results:EGFR was mutated in 21.6% of patients with 19.57% showing a mean expression. The most frequent EGFR mutation was a deletion in exon 19, followed by an L858R amino acid substitution in exon 21. KRAS was mutated in 26.4% of patients with 50% displaying mean expression. ALK rearrangement was detected in 6 patients (4.8%). Predominant acinar ADC was strongly associated with EGFR and KRAS mutation. Clinical stage, lymph node metastases, and EGFR mutation in exon 18 showed a significant difference in disease-free and overall survival, but only a trend significance for EGFR and KRAS mutations. Multivariate analysis revealed that men aged >71 years, with a history of smoking (<72 packs/year), clinical stage I/II, and acinar histologic subtype presented better survival than women aged ≤71 years, with a history of smoking (>72 packs/year), and having a predominant solid ADC and EGFR mutation in exon 18. Conclusions: These results indicate that the mutational profile and new IASLC/ATS/ERS classification provide additional prognostic information about lung ADC.

Whole-exome sequencing and functional studies identify RPS29 as a novel gene mutated in multicase Diamond-Blackfan anemia families

AbstractDiamond-Blackfan anemia (DBA) is a cancer-prone inherited bone marrow failure syndrome. Approximately half of DBA patients have a germ-line mutation in a ribosomal protein gene. We used whole-exome sequencing to identify disease-causing genes in 2 large DBA families. After filtering, 1 nonsynonymous mutation (p.I31F) in the ribosomal protein S29 (RPS29[AUQ1]) gene was present in all 5 DBA-affected individuals and the obligate carrier, and absent from the unaffected noncarrier parent in 1 DBA family. A second DBA family was found to have a different nonsynonymous mutation (p.I50T) in RPS29. Both mutations are amino acid substitutions in exon 2 predicted to be deleterious and resulted in haploinsufficiency of RPS29 expression compared with wild-type RPS29 expression from an unaffected control. The DBA proband with the p.I31F RPS29 mutation had a pre–ribosomal RNA (rRNA) processing defect compared with the healthy control. We demonstrated that both RPS29 mutations failed to rescue the defective erythropoiesis in the rps29−/− mutant zebra fish DBA model. RPS29 is a component of the small 40S ribosomal subunit and essential for rRNA processing and ribosome biogenesis. We uncovered a novel DBA causative gene, RPS29, and showed that germ-line mutations in RPS29 can cause a defective erythropoiesis phenotype using a zebra fish model.

Endothelin receptor B2 (EDNRB2) is responsible for the tyrosinase-independent recessive white (mo(w) ) and mottled (mo) plumage phenotypes in the chicken.

A mutation that confers white plumage with black eyes was identified in the Minohiki breed of Japanese native chicken (Gallus gallus domesticus). The white plumage, with a few partially pigmented feathers, was not associated with the tyrosinase gene, and displayed an autosomal recessive mode of inheritance against the pigmented phenotype. All F1 offspring derived from crosses with mottled chickens (mo/mo), which show characteristic pigmented feathers with white tips, had plumage with a mottled-like pattern. This result indicates that the white plumage mutation is a novel allele at the mo locus; we propose the gene symbol mow for this mutant allele. Furthermore, the F1 hybrid between the mow/mow chicken and the panda (s/s) mutant of Japanese quail (Coturnix japonica), whose causative gene is the endothelin receptor B2 (EDNRB2) gene, showed a mow/mow chicken-like plumage, suggesting the possibility that the mutations in parental species are alleles of the same gene, EDNRB2. Nucleotide sequencing of the entire coding region of EDNRB2 revealed a non-synonymous G1008T substitution, which causes Cys244Phe amino acid substitution in exon 5 (which is part of the extracellular loop between the putative fourth and fifth transmembrane domains of EDNRB2) in the mutant chicken. This Cys244Phe mutation was also present in individuals of four Japanese breeds with white plumage. We also identified a non-synonymous substitution leading to Arg332His substitution that was responsible for the mottled (mo/mo) plumage phenotype. These results suggest that the EDN3 (endothelin 3)–EDNRB2 signaling is essential for normal pigmentation in birds, and that the mutations of EDNRB2 may cause defective binding of the protein with endothelins, which interferes with melanocyte differentiation, proliferation, and migration.

Analysis of a Larger SNP Dataset from the HapMap Project Confirmed That the Modern Human A Allele of the ABO Blood Group Genes Is a Descendant of a Recombinant between B and O Alleles.

The human ABO blood group gene consists of three main alleles (A, B, and O) that encode a glycosyltransferase. The A and B alleles differ by two critical amino acids in exon 7, and the major O allele has a single nucleotide deletion (Δ261) in exon 6. Previous evolutionary studies have revealed that the A allele is the most ancient, B allele diverged from the A allele with two critical amino acid substitutions in exon 7, and the major O allele diverged from the A allele with Δ261 in exon 6. However, a recent phylogenetic network analysis study showed that the A allele of humans emerged through a recombination between the B and O alleles. In the previous study, a restricted dataset from only two populations was used. In this study, therefore, we used a large single nucleotide polymorphism (SNP) dataset from the HapMap Project. The results indicated that the A101-A201-O09 haplogroup was a recombinant lineage between the B and O haplotypes, containing the intact exon 6 from the B allele and the two critical A type sites in exon 7 from the major O allele. Its recombination point was assumed to be located just behind Δ261 in exon 6.

OP0023 Germinal and Somatic Genetic Variants of TNFAIP3 Promote Lymphomagenesis Process Complicating Primary Sjögren’s Syndrome

BackgroundThe pathophysiology of lymphomas in auto immune disease (AID) involves persistent inflammation and activation of autoimmune B cells leading to NF-kB activation. The TNFAIP3 gene encodes the A20 protein, a...

Epidermal growth factor receptor and KRAS mutations in Brazilian lung cancer patients

OBJECTIVE:Epidermal growth factor receptor is involved in the pathogenesis of non-small cell lung cancer and has recently emerged as an important target for molecular therapeutics. The KRAS oncogene also plays an important role in the development of lung cancer. The aim of this study was to evaluate the frequency of epidermal growth factor receptor and KRAS mutations in a population of Brazilian patients with non-small cell lung cancer.METHODS:A total of 207 specimens from Brazilian patients with non-small cell lung cancer were analyzed for activating epidermal growth factor receptor and KRAS somatic mutations, and their associations with clinicopathological characteristics (including age, gender, ethnicity, smoking habits, and histological subtype) were examined.RESULTS:We identified 63 cases (30.4%) with epidermal growth factor receptor mutations and 30 cases (14.6%) with KRAS mutations. The most frequent epidermal growth factor receptor mutation we detected was a deletion in exon 19 (60.3%, 38 patients), followed by an L858R amino acid substitution in exon 21 (27%, 17 patients). The most common types of KRAS mutations were found in codon 12. There were no significant differences in epidermal growth factor receptor or KRAS mutations by gender or primary versus metastatic lung cancer. There was a higher prevalence of KRAS mutations in the non-Asian patients. Epidermal growth factor receptor mutations were more prevalent in adenocarcinomas than in non-adenocarcinoma histological types. Being a non-smoker was significantly associated with the prevalence of epidermal growth factor receptor mutations, but the prevalence of KRAS mutations was significantly associated with smoking.CONCLUSIONS:This study is the first to examine the prevalence of epidermal growth factor receptor and KRAS mutations in a Brazilian population sample with non-small cell lung cancer.

Non-synonymous polymorphism in the neuropeptide S precursor gene and sleep apnea

Obstructive sleep apnea syndrome (OSAS) is a complex disease with a strong genetic basis. One of the primary molecular domains affected by OSAS is sympathetic activity. Neuropeptide S (NPS) plays an important role in the regulation of the sleep-wakefulness cycle, anxiety states, and daytime sleepiness. It is important to study neuropeptides related to sympathetic activity regulation and how their function could be modified by genetic variants affecting the expression of these molecules. We investigated the association of the non-synonymous polymorphism rs4751440 in the NPS precursor gene with OSAS and certain variables related to OSAS (daytime sleepiness, body mass index (BMI), insulin resistance, and blood pressure). This polymorphism causes an amino acid substitution in exon 3 of the human NPS precursor gene. We included 253 OSAS patients and 70 healthy subjects. Genotyping was done by polymerase chain reaction using specific flanking primers and agarose gel electrophoresis. Daytime sleepiness, BMI, plasma levels of high-density lipoprotein, glucose, total cholesterol, insulin, triglycerides, and the homeostasis model assessment index were also determined. A similar genotypic and allelic distribution was found in OSAS patients and controls. The risk of OSAS was not associated with the rs4751440 polymorphism. There was no significant interaction between daytime sleepiness or metabolic variables and the rs4751440 polymorphism. Genotypic and allelic frequency distribution of the rs4751440 polymorphism was similar in OSAS patients and controls. In this population-based study, we could not show a significant association between rs4751440 polymorphism and susceptibility to OSAS or certain phenotypes related to OSAS (daytime sleepiness, BMI, systolic blood pressure, and insulin resistance) with the exception of diastolic blood pressure.

The Soybean Stem Growth Habit Gene Dt1 Is an Ortholog of Arabidopsis TERMINAL FLOWER1

Classical genetic analysis has revealed that the determinate habit of soybean (Glycine max) is controlled by a recessive allele at the determinate stem (Dt1) locus. To dissect the molecular basis of the determinate habit, we isolated two orthologs of pea (Pisum sativum) TERMINAL FLOWER1a, GmTFL1a and GmTFL1b, from the soybean genome. Mapping analysis indicated that GmTFL1b is a candidate for Dt1. Despite their high amino acid identity, the two genes had different transcriptional profiles. GmTFL1b was expressed in the root and shoot apical meristems (SAMs), whereas GmTFL1a was mainly expressed in immature seed. The GmTFL1b transcript accumulated in the SAMs during early vegetative growth in both the determinate and indeterminate lines but thereafter was abruptly lost in the determinate line. Introduction of the genomic region of GmTFL1b from the indeterminate line complemented the stem growth habit in the determinate line: more nodes were produced, and flowering in the terminal raceme was delayed. The identity between Dt1 and GmTFL1b was also confirmed with a virus-induced gene silencing experiment. Taken together, our data suggest that Dt1 encodes the GmTFL1b protein and that the stem growth habit is determined by the variation of this gene. The dt1 allele may condition the determinate habit via the earlier loss in GmTFL1b expression concomitant with floral induction, although it functions normally under the noninductive phase of flowering. An association test of DNA polymorphisms with the stem growth habit among 16 cultivars suggested that a single amino acid substitution in exon 4 determines the fate of the SAM after floral induction.

An autopsy case of rhabdomyolysis related to vegetamin and genetic analysis of the rhabdomyolysis-associated genes

We report an autopsy case of a man who died 2 days after taking an overdose of vegetamin. The autopsy findings were as follows: the epidermis on the axillary fossa and the inguinal skin had become macerated. Skeletal muscle was discolored. Concentrations of urea nitrogen, creatinine and urine myoglobin were 1.95 g/day, 0.66 g/day and 1100 ng/mL, respectively. Immunohistochemically, myoglobin was strongly stained at the Bowman’s capsule, and tubular lumen and epithelium. 8-OH-dG was strongly stained in renal tubular epithelium in which cell nuclei were strongly stained. ORP-150 was observed in intraglomerular cells and renal tubular epithelium. The concentrations of phenobarbital, promethazine and chlorpromazine ranged from therapeutic to toxic levels, from toxic to lethal levels and toxic level, respectively. His cause of death was considered to be vegetamin-induced rhabdomyolysis. In genetic analysis of this subject, there were two heterozygous silent mutations in the three hot-spot regions in the RYR1 gene. In the CPT II gene, the subject was found to be heterozygous for an amino acid substitution in exon 4, 1203G > A causing a 368Val > Ile amino acid substitution. There was no mutation in the VLCAD gene or CYP2C19 gene. The subject was heterozygous for CYP2D6*1 and CYP2D6*2.

EGFR Mutations are More Frequent in Well-Differentiated than in Poor-Differentiated Lung Adenocarcinomas

Somatic mutations in epidermal growth factor receptor (EGFR) tyrosine kinase domain, particularly deletions in exon 19 and point mutation in exon 21, are associated with clinical outcome in patients with lung adenocarcinoma, suggesting that EGFR mutation would have an important role in clinical decision making. DNA was extracted from the excised specimens of 60 lung adenocarcinoma patients with phenol-chloroform and ethanol precipitation. Exon 19 and 21 were amplified by PCR, and direct sequenced from both sense and antisense directions. EGFR somatic mutations were present in 13 of 60 patients (21.67%), including seven cases of in-frame deletion in exon 19 around codon 746 and six cases of amino acid substitution in exon 21. Exon 21 mutation is more frequent in adenocarcinomas with bronchi-alveolar component than exon 19 deletions. Mutations were more prevalent in well-differentiated adenocarcinomas (9/27, 33.33%) than in moderate to poor-differentiated adenocarcinomas (4/33, 12.12%) (P < 0.05). Adenocarcinomas with bronchi-alveolar components had higher mutation frequency (8/22,36. 36%) than those without bronchi-alveolar components (5/38, 13.16%) (P < 0.05). In this study, female patients had more mutation rate than male patients. This trend was also observed in the patients with pathologic stage I-II compared with stage III-IV, but neither of them was statistically significant. Patients with cisplatin-based adjuvant chemotherapy had no significantly prolonged survival compared with single radical resection. But patients with EGFR mutation had relative longer survival. In conclusion, our study suggest that EGFR mutations may be a valuable prognostic factor for disease free survival of surgically treated lung adenocarcinoma patients independently from adjuvant chemotherapy.

Analysis of epidermal growth factor receptor(EGFR) mutations in non-small-cell lung cancer patients in Fujian province

Objective To analyze the epidemud growth factor receptor(EGFR)mutations in NSCLC patients in Fujian province.Methods Fresh specimens of lung cancer and corresponding normal lung tissue were collected from 50 cases of NSCLC patients.After DNA extraction,nested polymerase chain reaction (nested PCR)and direct deoxyribonucleic acid(DNA)sequencing were used to analyze EGFR gene mutations in NSCLC patients.Results EGFR mutations in tumors were identified from 13 of 50(26%)patients,including 10 cages of in-frame deletion in exon 19 and 3 cases of amino acid substitution in exon 21.Conclusion The mjor type of EGFR mutation in NSCLC patients in Fujian is in-frame deletion in exon 19. Key words: Carcinoma,non-small-ceu lung; Receptor,epidermal growth factor,Gene; Mutation

Genetic and biochemical studies in Argentinean patients with variegate porphyria.

BackgroundA partial deficiency in Protoporphyrinogen oxidase (PPOX) produces the mixed disorder Variegate Porphyria (VP), the second acute porphyria more frequent in Argentina. Identification of patients with an overt VP is absolutely important because treatment depends on an accurate diagnosis but more critical is the identification of asymptomatic relatives to avoid acute attacks which may progress to death.MethodsWe have studied at molecular level 18 new Argentinean patients biochemically diagnosed as VP. PPOX gene was amplified in one or in twelve PCR reactions. All coding exons, flanking intronic and promoter regions were manual or automatically sequenced. For RT-PCR studies RNA was retrotranscripted, amplified and sequenced. PPOX activity in those families carrying a new and uncharacterized mutation was performed.ResultsAll affected individuals harboured mutations in heterozygous state. Nine novel mutations and 3 already reported mutations were identified. Six of the novel mutations were single nucleotide substitutions, 2 were small deletions and one a small insertion. Three single nucleotide substitutions and the insertion were at exon-intron boundaries. Two of the single nucleotide substitutions, c.471G>A and c.807G>A and the insertion (c.388+3insT) were close to the splice donor sites in exons 5, 7 and intron 4 respectively. The other single nucleotide substitution was a transversion in the last base of intron 7, g.3912G>C (c.808-1G>C) so altering the consensus acceptor splice site. However, only in the first case the abnormal band showing the skipping of exon 5 was detected. The other single nucleotide substitutions were transversions: c.101A>T, c.995G>C and c.670 T>G that result in p.E34V, p.G332A and W224G aminoacid substitutions in exons 3, 10 and 7 respectively. Activity measurements indicate that these mutations reduced about 50% PPOX activity and also that they co-segregate with this reduced activity value. Two frameshift mutations, c.133delT and c.925delA, were detected in exons 3 and 9 respectively. The first leads to an early termination signal 22 codons downstream (p.S45fsX67) and the second leads to a stop codon 5 codons downstream (p.I309fsX314). One reported mutation was a missense mutation (p.G232R) and 2 were frameshift mutations: c.1082insC and 1043insT. The last mutation was detected in six new apparently unrelated Argentinean families.ConclusionMolecular analysis in available family members revealed 14 individuals who were silent carriers of VP. Molecular techniques represent the most accurate approach to identify unaffected carriers and to provide accurate genetic counselling for asymptomatic individuals. The initial screening includes the insertion search.

Mutation of the Wilms' Tumor 1 Gene Is a Poor Prognostic Factor Associated with Chemoresistance in Normal Karyotype Acute Myeloid Leukemia.

The Wilms' tumour 1 (WT1) gene is highly expressed in various types of leukemia, suggesting a role both as a target for immunotherapy and a means for monitoring minimal residual disease. More recently WT1 has been recognised as an important mutational target in normal karyotype (NK) acute myeloid leukemia (AML), with clustering of mutations to exons 7 and 9. In this study, we set out to determine the clinical relevance of these mutations. Diagnostic DNA samples were obtained from peripheral blood or bone marrow of 470 young adult AML patients entered into the UK Medical Research Council AML 10 and 12 trials. Mutation analysis was performed using standard PCR-based direct sequencing and/or high-resolution capillary electrophoresis of exons 7 and 9. Overall, 51 mutations were observed in 47 cases (10%). Of these, 42 cases had 46 frameshift mutations arising from insertions (n=41) or deletions (n=5) of between 1 and 28 bps that would result in disruption of the C-terminal DNA binding domain of the protein. Median mutant level was 45% (range 8–86%). The remaining 5 cases were non-synonymous amino acid substitutions in exon 9, D396N (n=3) which is implicated in Denys-Drash syndrome, and 1 each of H397Y and H397Q that are of unknown functional significance. There was a borderline inverse relationship between the presence of WT1 mutations and NPM1 exon 12 mutations (p=.05), and an increased proportion of FLT3-ITDs in WT1 mutant cases (p=.08). In order to determine the clinical relevance of WT1 mutations we compared patient characteristics between WT1 mutated and WT1 wild-type cases. There was no difference between the 2 groups in age, gender, presenting WBC, or type of AML (de novo/secondary). Patients with WT1 mutations had an inferior response to therapy compared to WT1 wild-type cases (complete remission [CR] 79% Vs 90% respectively, odds ratio [OR] 3.02, 95% confidence intervals [CI] 1.17–7.82, p=.02) which was due to a higher rate of resistant disease (RD) (15% Vs 4%, OR 9.33, CI 2.38–36.6, p=.001). In univariate analysis mutated cases also had a significantly reduced disease free survival (DFS), 22% Vs 44% at 5 years (OR 2.16, CI 1.32–3.55, p=.005) and overall survival (OS), 26% Vs 47%, OR 1.91, CI 1.23–2.95, p=.007). In multivariate analysis considering age, gender, type of leukemia, WBC, FLT3-ITD and NPM1 mutant status, a WT1 mutation remained an independent adverse prognostic factor for both response to therapy (CR: OR 3.19, CI 1.25–8.13, p=.01; RD: OR 4.93, CI 1.58–15.37, p=.006) and survival (DFS: OR 1.60, CI 1.07–2.38, p=.02; OS: OR 1.52, CI 1.05–2.18, p=.03). These results indicate that WT1 mutations are an additional prognostic marker in NK AML and may be suitable for targeted therapy.

Mutation in Filamin A Causes Periventricular Heterotopia, Developmental Regression, and West Syndrome in Males

Familial periventricular heterotopia (PH) represents a disorder of neuronal migration resulting in multiple gray-matter nodules along the lateral ventricular walls. Prior studies have shown that mutations in the filamin A (FLNA) gene can cause PH through an X-linked dominant pattern. Heterozygotic female patients usually remain asymptomatic until the second or third decade of life, when they may have predominantly focal seizures, whereas hemizygotic male fetuses typically die in utero. Recent studies have also reported mutations in FLNA in male patients with PH who are cognitively normal. We describe PH in three male siblings with PH due to FLNA, severe developmental regression, and West syndrome. The study includes the three affected brothers and their parents. Video-EEG recordings and magnetic resonance image (MRI) scanning were performed on all individuals. Mutations for FLNA were detected by using polymerase chain reaction (PCR) on genomic DNA followed by single-stranded conformational polymorphism (SSCP) analysis or sequencing. Two of the siblings are monozygotic twins, and all had West syndrome with hypsarrhythmia on EEG. MRI of the brain revealed periventricular nodules of cerebral gray-matter intensity, typical for PH. Mutational analyses demonstrated a cytosine-to-thymidine missense mutation (c. C1286T), resulting in a threonine-to-methionine amino acid substitution in exon 9 of the FLNA gene. The association between PH and West syndrome, to our knowledge, has not been previously reported. Males with PH have been known to harbor FLNA mutations, although uniformly, they either show early lethality or survive and have a normal intellect. The current studies show that FLNA mutations can cause periventricular heterotopia, developmental regression, and West syndrome in male patients, suggesting that this type of FLNA mutation may contribute to severe neurologic deficits.

Somatic Mutations of KIT in Familial Testicular Germ Cell Tumours

No AccessJournal of UrologyAdult Urology: Urological Survey: Urological Oncology: Testis Cancer and Advances in Oncological Therapy1 Mar 2005Somatic Mutations of KIT in Familial Testicular Germ Cell Tumours Jerome P. RichieM.D. Jerome P. RichieJerome P. Richie More articles by this author View All Author Informationhttps://doi.org/10.1016/S0022-5347(05)60349-7AboutFull TextPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail "Somatic Mutations of KIT in Familial Testicular Germ Cell Tumours." The Journal of Urology, 173(3), pp. 833–834 © 2005 by American Urological Association, Inc.FiguresReferencesRelatedDetails Volume 173Issue 3March 2005Page: 833-834 Advertisement Copyright & Permissions© 2005 by American Urological Association, Inc.MetricsAuthor Information Jerome P. Richie More articles by this author Expand All Advertisement PDF downloadLoading ...

Not All Amino Acid Substitutions of the Common Cluster E6 Mutation inCYP21Cause Congenital Adrenal Hyperplasia

More than 90% of all cases of congenital adrenal hyperplasia result from steroid 21-hydroxylase (CYP21) gene mutations. Around 95% of these are either gene deletions or any of nine sequence aberrations that have been transferred from the nearby pseudogene through apparent gene conversions. One such recurrent pseudogene-derived mutation is Cluster E6, a combination of three amino acid substitutions in exon 6: I236N, V237E, and M239K. Cluster E6 is associated with the most severe, salt-wasting form of congenital adrenal hyperplasia. We studied the functional consequences of each missense mutation individually as well as the combined effect of the three mutations comprising Cluster E6. V237E abolished enzyme function and is thus a null mutation, whereas very low but measurable activity remained for I236N. M239K, on the other hand, had no effect on enzyme activity and consequently does not contribute to the disease. Although no allele has been reported yet to contain only one or two missense mutations of Cluster E6, it is a well-known feature of CYP21 that it can harbor many different combinations of pseudogene-derived mutations. The exclusion of M239K as a disease-causing mutation is thus relevant when designing protocols for genetic diagnostics.

FoxP2 in Song-Learning Birds and Vocal-Learning Mammals

FoxP2 is the first identified gene that is specifically involved in speech and language development in humans. Population genetic studies of FoxP2 revealed a selective sweep in recent human history associated with two amino acid substitutions in exon 7. Avian song learning and human language acquisition share many behavioral and neurological similarities. To determine whether FoxP2 plays a similar role in song-learning birds, we sequenced exon 7 of FoxP2 in multiple song-learning and nonlearning birds. We show extreme conservation of FoxP2 sequences in birds, including unusually low rates of synonymous substitutions. However, no amino acid substitutions are shared between the song-learning birds and humans. Furthermore, sequences from vocal-learning whales, dolphins, and bats do not share the human-unique substitutions. While FoxP2 appears to be under strong functional constraints in mammals and birds, we find no evidence for its role during the evolution of vocal learning in nonhuman animals as in humans.

Somatic mutations of KIT in familial testicular germ cell tumours.

Somatic mutations of the KIT gene have been reported in mast cell diseases and gastrointestinal stromal tumours. Recently, they have also been found in mediastinal and testicular germ cell tumours (TGCTs), particularly in cases with bilateral disease. We screened the KIT coding sequence (except exon 1) for germline mutations in 240 pedigrees with two or more cases of TGCT. No germline mutations were found. Exons 10, 11 and 17 of KIT were examined for somatic mutations in 123 TGCT from 93 multiple-case testicular cancer families. Five somatic mutations were identified; four were missense amino-acid substitutions in exon 17 and one was a 12 bp in-frame deletion in exon 11. Two of seven TGCT from cases with bilateral disease carried KIT mutations compared with three out of 116 unilateral cases (P=0.026). The results indicate that somatic KIT mutations are implicated in the development of a minority of familial as well as sporadic TGCT. They also lend support to the hypothesis that KIT mutations primarily take place during embryogenesis such that primordial germ cells with KIT mutations are distributed to both testes.

Genetic and functional analysis of single nucleotide polymorphisms in the beta2-neuronal nicotinic acetylcholine receptor gene (CHRNB2).

The beta2-neuronal nicotinic acetylcholine receptor gene (CHRNB2) is a logical candidate for influencing smoking behavior and nicotine dependence. We discovered six single nucleotide polymorphisms (SNPs) in the CHRNB2 gene by surveying 15.4 kb of genomic sequence including a previously undescribed 3' untranslated region that extends 4.0 kb downstream of the coding region. One of the SNPs causes an amino acid substitution in exon 5, one occurs in the promoter region, one changes an intronic base, and three occur in the 3' untranslated region. The ethnically dependent allele frequencies and the marker-to-marker linkage disequilibrium patterns of five of these polymorphisms were determined. The SNPs were assayed in 743 individuals for whom information on smoking history and lifelong nicotine dependence was available. No significant associations of the individual markers or their haplotypes to smoking behavior or level of nicotine dependence were found.