scholarly journals Mutations in Human Urate Transporter 1 Gene in Presecretory Reabsorption Defect Type of Familial Renal Hypouricemia

2005 ◽  
Vol 90 (4) ◽  
pp. 2169-2174 ◽  
Author(s):  
Naoki Wakida ◽  
Do Gia Tuyen ◽  
Masataka Adachi ◽  
Taku Miyoshi ◽  
Hiroshi Nonoguchi ◽  
...  
Keyword(s):  
Mutational Analysis ◽  
Novel Mutation ◽  
Direct Sequencing ◽  
Loss Of Function ◽  
Wild Type ◽  
Coding Region ◽  
Renal Hypouricemia ◽  
Defect Type ◽  
Urate Transporter ◽  
Idiopathic Renal Hypouricemia

Abstract To date, 11 loss of function mutations in the human urate transporter 1 (hURAT1) gene have been identified in subjects with idiopathic renal hypouricemia. In the present studies we investigated the clinical features and the mutations in the hURAT1 gene in seven families with presecretory reabsorption defect-type renal hypouricemia and in one family with the postsecretory reabsorption defect type. Twelve affected subjects and 26 family members were investigated. Mutations were analyzed by PCR and the direct sequencing method. Urate-transporting activities of wild-type and mutant hURAT1 were determined by [14C]urate uptake in Xenopus oocytes. Mutational analysis revealed three previously reported mutations (G774A, A1145T, and 1639–1643 del-GTCCT) and a novel mutation (T1253G) in families with the presecretory reabsorption defect type. Neither mutations in the coding region of hURAT1 gene nor significant segregation patterns of the hURAT1 locus were detected in the postsecretory reabsorption defect type. All hURAT1 mutants had significantly reduced urate-transporting activities compared with wild type (P < 0.05; n = 12), suggesting that T1253G is a loss of function mutation, and hURAT1 is responsible for the presecretory reabsorption defect-type familial renal hypouricemia. Future studies are needed to identify a responsible gene for the postsecretory reabsorption defect-type familial renal hypouricemia.

scholarly journals Goα Regulates Volatile Anesthetic Action in Caenorhabditis elegans

Genetics ◽  
2001 ◽  
Vol 158 (2) ◽  
pp. 643-655 ◽  
Author(s):  
Bruno van Swinderen ◽  
Laura B Metz ◽  
Laynie D Shebester ◽  
Jane E Mendel ◽  
Paul W Sternberg ◽  
...  
Keyword(s):  
Caenorhabditis Elegans ◽  
Novel Mutation ◽  
Volatile Anesthetic ◽  
Loss Of Function ◽  
Wild Type ◽  
Α Subunit ◽  
C Elegans ◽  
Missense Mutant ◽  
Anesthetic Action ◽  
Mutant Phenotypes

Abstract To identify genes controlling volatile anesthetic (VA) action, we have screened through existing Caenorhabditis elegans mutants and found that strains with a reduction in Go signaling are VA resistant. Loss-of-function mutants of the gene goa-1, which codes for the α-subunit of Go, have EC50s for the VA isoflurane of 1.7- to 2.4-fold that of wild type. Strains overexpressing egl-10, which codes for an RGS protein negatively regulating goa-1, are also isoflurane resistant. However, sensitivity to halothane, a structurally distinct VA, is differentially affected by Go pathway mutants. The RGS overexpressing strains, a goa-1 missense mutant found to carry a novel mutation near the GTP-binding domain, and eat-16(rf) mutants, which suppress goa-1(gf) mutations, are all halothane resistant; goa-1(null) mutants have wild-type sensitivities. Double mutant strains carrying mutations in both goa-1 and unc-64, which codes for a neuronal syntaxin previously found to regulate VA sensitivity, show that the syntaxin mutant phenotypes depend in part on goa-1 expression. Pharmacological assays using the cholinesterase inhibitor aldicarb suggest that VAs and GOA-1 similarly downregulate cholinergic neurotransmitter release in C. elegans. Thus, the mechanism of action of VAs in C. elegans is regulated by Goα, and presynaptic Goα-effectors are candidate VA molecular targets.

scholarly journals Adrenocorticotropin-Dependent Precocious Puberty of Testicular Origin in a Boy with X-Linked Adrenal Hypoplasia Congenita Due to a Novel Mutation in the DAX1 Gene

2001 ◽  
Vol 86 (9) ◽  
pp. 4068-4071 ◽  
Author(s):  
Sorahia Domenice ◽  
Ana Claudia Latronico ◽  
Vinicius Nahime Brito ◽  
Ivo Jorge Prado Arnhold ◽  
Fernando Kok ◽  
...  
Keyword(s):  
Adrenal Insufficiency ◽  
Precocious Puberty ◽  
Stop Codon ◽  
Novel Mutation ◽  
Direct Sequencing ◽  
Receptor Gene ◽  
Premature Stop Codon ◽  
Rare Condition ◽  
Coding Region ◽  
Primary Adrenal Insufficiency

Primary adrenal insufficiency is a rare condition in pediatric age, and its association with precocious sexual development is very uncommon. We report a 2-yr-old Brazilian boy with DAX1 gene mutation whose first clinical manifestation was isosexual gonadotropin-independent precocious puberty. He presented with pubic hair, enlarged penis and testes, and advanced bone age. T levels were elevated, whereas basal and GnRH-stimulated LH levels were compatible with a prepubertal pattern. Chronic GnRH agonist therapy did not reduce T levels, supporting the diagnosis of gonadotropin-independent precocious puberty. Testotoxicosis was ruled out after normal sequencing of exon 11 of the LH receptor gene. At age 3 yr he developed clinical and hormonal features of severe primary adrenal insufficiency. The entire coding region of the DAX1 gene was analyzed through direct sequencing. A nucleotide G insertion between nucleotides 430 and 431 in exon 1, resulting in a novel frameshift mutation and a premature stop codon at position 71 of DAX-1, was identified. Surprisingly, steroid replacement therapy induced a clear decrease in testicular size and T levels to the prepubertal range. These findings suggest that chronic excessive ACTH levels resulting from adrenal insufficiency may stimulate Leydig cells and lead to gonadotropin-independent precocious puberty in some boys with DAX1 gene mutations.

Mutational analysis of idiopathic renal hypouricemia in Korea

2005 ◽  
Vol 20 (7) ◽  
pp. 886-890 ◽  
Author(s):  
Hae Il Cheong ◽  
Ju Hyung Kang ◽  
Joo Hoon Lee ◽  
Il Soo Ha ◽  
Suhnggwon Kim ◽  
...  
Keyword(s):  
Mutational Analysis ◽  
Renal Hypouricemia ◽  
Idiopathic Renal Hypouricemia

scholarly journals Mutational analysis of TAC3 and TACR3 genes in patients with idiopathic central pubertal disorders

2012 ◽  
Vol 56 (9) ◽  
pp. 646-652 ◽  
Author(s):  
Cintia Tusset ◽  
Sekoni D. Noel ◽  
Ericka B. Trarbach ◽  
Letícia F. G. Silveira ◽  
Alexander A. L. Jorge ◽  
...  
Keyword(s):  
Genomic Dna ◽  
Rare Variants ◽  
Mutational Analysis ◽  
Pubertal Development ◽  
Hypogonadotropic Hypogonadism ◽  
Central Precocious Puberty ◽  
Control Group ◽  
Loss Of Function ◽  
Coding Region ◽  
Constitutional Delay

OBJECTIVE: To investigate the presence of variants in the TAC3 and TACR3 genes, which encode NKB and its receptor (NK3R), respectively, in a large cohort of patients with idiopathic central pubertal disorders. SUBJECTS AND METHODS: Two hundred and thirty seven patients were studied: 114 with central precocious puberty (CPP), 73 with normosmic isolated hypogonadotropic hypogonadism (IHH), and 50 with constitutional delay of growth and puberty (CDGP). The control group consisted of 150 Brazilian individuals with normal pubertal development. Genomic DNA was extracted from peripheral blood and the entire coding region of both TAC3 and TACR3 genes were amplified and automatically sequenced. RESULTS: We identified one variant (p.A63P) in NKB and four variants, p.G18D, p.L58L (c.172C>T), p.W275* and p.A449S in NK3R, which were absent in the control group. The p.A63P variant was identified in a girl with CPP, and p.A449S in a girl with CDGP. The known p.G18D, p.L58L, and p.W275* variants were identified in three unrelated males with normosmic IHH. CONCLUSION: Rare variants in the TAC3 and TACR3 genes were identified in patients with central pubertal disorders. Loss-of-function variants of TACR3 were associated with the normosmic IHH phenotype. Arq Bras Endocrinol Metab. 2012;56(9):646-52

scholarly journals Hyperinsulinism of Infancy: Novel ABCC8 and KCNJ11 Mutations and Evidence for Additional Locus Heterogeneity

2004 ◽  
Vol 89 (12) ◽  
pp. 6224-6234 ◽  
Author(s):  
Sharona Tornovsky ◽  
Ana Crane ◽  
Karen E. Cosgrove ◽  
Khalid Hussain ◽  
Judith Lavie ◽  
...  
Keyword(s):  
Novel Mutation ◽  
Direct Sequencing ◽  
Expression System ◽  
Severe Hypoglycemia ◽  
K Channel ◽  
Missense Mutations ◽  
Sulfonylurea Receptor ◽  
Coding Region ◽  
Locus Heterogeneity ◽  
Additional Locus

Abstract Hyperinsulinism of infancy is a genetically heterogeneous disease characterized by dysregulation of insulin secretion resulting in severe hypoglycemia. To date, mutations in five different genes, the sulfonylurea receptor (SUR1, ABCC8), the inward rectifying potassium channel (KIR6.2, KCNJ11), glucokinase (GCK), glutamate dehydrogenase (GLUD1), and short-chain 3-hydroxyacyl-coenzyme A dehydrogenase (SCHAD), have been implicated. Previous reports suggest that, in 40% of patients, no mutation can be identified in any of these genes, suggesting additional locus heterogeneity. However, previous studies did not screen all five genes using direct sequencing, the most sensitive technique available for mutation detection. We selected 15 hyperinsulinism of infancy patients and systematically sequenced the promoter and all coding exons and intron/exon boundaries of ABCC8 and KCNJ11. If no mutation was identified, the coding sequence and intron/exon boundaries of GCK, GLUD1, and SCHAD were sequenced. Seven novel mutations were found in the ABCC8 coding region, one mutation was found in the KCNJ11 coding region, and one novel mutation was found in each of the two promoter regions screened. Functional studies on β-cells from six patients showed abnormal ATP-sensitive K+ channel function in five of the patients; the sixth had normal channel activity, and no mutations were found. Photolabeling studies using a reconstituted system showed that all missense mutations altered intracellular trafficking. Each of the promoter mutations decreased expression of a reporter gene by about 60% in a heterologous expression system. In four patients (27%), no mutations were identified. Thus, further genetic heterogeneity is suggested in this disorder. These patients represent a cohort that can be used for searching for mutations in other candidate genes.

scholarly journals Mutational Analysis of a Novel Mutation (p.H232R) in the SRD5A2 Causing 46,XY Disorder of Sex Development

2021 ◽  
Author(s):  
Liwei Li ◽  
Junhong Zhang ◽  
Qing Li ◽  
Li Qiao ◽  
Pengcheng Li ◽  
...  
Keyword(s):  
Molecular Mechanism ◽  
Mutational Analysis ◽  
Novel Mutation ◽  
Catalytic Efficiency ◽  
Hek293 Cells ◽  
Compound Heterozygous ◽  
Wild Type ◽  
Disorder Of Sex Development ◽  
Maternal Grandfather ◽  
Sex Development

Abstract Background: Over 100 mutations in SRD5A2 gene have been identified in subjects with 46,XY DSD. Exploring SRD5A2 mutation and elucidating its molecular mechanism will find the domains function of 5α-reductase 2 enzyme and identify the cause of 46,XY DSD. Previously, we reported a novel compound heterozygous p.H232R/p.Q6X mutation of SRD5A2 gene in a case with 46,XY DSD. Whether the compound heterozygous p.Q6X/p.H232R mutation in SRD5A2 gene causes 46,XY DSD occurrence is needed to be further explored. Results: In order to clarify the cause of 46,XY DSD in the case’s family, SRD5A2 sequencing were performed. The heterozygous p.H232R mutation were identified in the case’s father, so we concluded that the heterozygous p.H232R mutation originated from paternal family and didn’t cause 46,XY DSD occurrence. The heterozygous p.Q6X mutation were identified in the case’s mother, maternal uncle and maternal grandfather, indicating that the heterozygous p.Q6X mutation descended from maternal family and didn’t cause 46,XY DSD occurrence. In order to clarify p.H232R mutation in SRD5A2 on DHT production, p.H232R mutant SRD5A2 plasmids were transfected with HEK293 cells and LC-MS detected that DHT production decreased compared with wild-type SRD5A2 infected ones.Conclusions: Our findings confirmed that the compound heterozygous p.Q6X/p.H232R mutation in SRD5A2 gene is the cause of 46,XY DSD. p.H232R mutation reduced DHT production while attenuated 5α-reductase 2 enzymatic catalytic efficiency.

scholarly journals Central Precocious Puberty Caused by a Heterozygous Deletion in the MKRN3 Promoter Region

2018 ◽  
Vol 107 (2) ◽  
pp. 127-132 ◽  
Author(s):  
Delanie B. Macedo ◽  
Monica M. França ◽  
Luciana R. Montenegro ◽  
Marina Cunha-Silva ◽  
Danielle S. Bessa ◽  
...  
Keyword(s):  
Precocious Puberty ◽  
Promoter Region ◽  
Regulatory Region ◽  
In Silico Analysis ◽  
Central Precocious Puberty ◽  
Proximal Promoter ◽  
Loss Of Function ◽  
Wild Type ◽  
Coding Region ◽  
Blood Leukocytes

Context: Loss-of-function mutations in the coding region of MKRN3, a maternally imprinted gene at chromosome 15q11.2, are a common cause of familial central precocious puberty (CPP). Whether MKRN3 alterations in regulatory regions can cause CPP has not been explored to date. We aimed to investigate potential pathogenic variants in the promoter region of MKRN3 in patients with idiopathic CPP. Patients/Methods: A cohort of 110 patients with idiopathic CPP was studied. Family history of precocious sexual development was present in 25%. Mutations in the coding region of MKRN3 were excluded in all patients. Genomic DNA was extracted from peripheral blood leukocytes, and 1,100 nucleotides (nt) of the 5′-regulatory region of MKRN3 were amplified and sequenced. Luciferase assays were performed in GT1–7 cells transiently transfected with plasmids containing mutated and wild-type MKRN3 promoter. Results: We identified a rare heterozygous 4-nt deletion (c.-150_-147delTCAG; –38 to –41 nt upstream to the transcription start site) in the proximal promoter region of MKRN3 in a girl with CPP. In silico analysis predicted that this deletion would lead to the loss of a binding site for a downstream res­ponsive element antagonist modulator (DREAM), a potential transcription factor for MKRN3 and GNRH1 expression. Luciferase assays demonstrated a significant reduction of MKRN3 promoter activity in transfected cells with a c.-150_- 147delTCAG construct plasmid in both homozygous and heterozygous states when compared with cells transfected with the corresponding wild-type MKRN3 promoter region. Conclusion: A rare genetic alteration in the regulatory region of MKRN3 causes CPP.

scholarly journals Lethal digenic mutations in the K+ channels Kir4.1 (KCNJ10) and SLACK (KCNT1) associated with severe-disabling seizures and neurodevelopmental delay

2017 ◽  
Vol 118 (4) ◽  
pp. 2402-2411 ◽  
Author(s):  
Sonia Hasan ◽  
Ameera Balobaid ◽  
Alessandro Grottesi ◽  
Omar Dabbagh ◽  
Marta Cenciarini ◽  
...  
Keyword(s):  
Novel Mutation ◽  
Failure To Thrive ◽  
Xenopus Laevis Oocytes ◽  
Loss Of Function ◽  
Wild Type ◽  
Neurodevelopmental Delay ◽  
Whole Exome ◽  
Dependent Inhibition ◽  
Clonic Seizures

A 2-yr-old boy presented profound developmental delay, failure to thrive, ataxia, hypotonia, and tonic-clonic seizures that caused the death of the patient. Targeted and whole exome sequencing revealed two heterozygous missense variants: a novel mutation in the KCNJ10 gene that encodes for the inward-rectifying K+ channel Kir4.1 and another previously characterized mutation in KCNT1 that encodes for the Na+-activated K+ channel known as Slo2.2 or SLACK. The objectives of this study were to perform the clinical and genetic characterization of the proband and his family and to examine the functional consequence of the Kir4.1 mutation. The mutant and wild-type KCNJ10 constructs were generated and heterologously expressed in Xenopus laevis oocytes, and whole cell K+ currents were measured using the two-electrode voltage-clamp technique. The KCNJ10 mutation c.652C>T resulted in a p.L218F substitution at a highly conserved residue site. Wild-type KCNJ10 expression yielded robust Kir current, whereas currents from oocytes expressing the mutation were reduced, remarkably. Western Blot analysis revealed reduced protein expression by the mutation. Kir5.1 subunits display selective heteromultimerization with Kir4.1 constituting channels with unique kinetics. The effect of the mutation on Kir4.1/5.1 channel activity was twofold: a reduction in current amplitudes and an increase in the pH-dependent inhibition. We thus report a novel loss-of-function mutation in Kir4.1 found in a patient with a coexisting mutation in SLACK channels that results in a fatal disease. NEW & NOTEWORTHY We present and characterize a novel mutation in KCNJ10. Unlike previously reported EAST/SeSAME patients, our patient was heterozygous, and contrary to previous studies, mimicking the heterozygous state by coexpression resulted in loss of channel function. We report in the same patient co-occurrence of a KCNT1 mutation resulting in a more severe phenotype. This study provides new insights into the phenotypic spectrum and to the genotype-phenotype correlations associated with EAST/SeSAME and MMFSI.

Mutational Analysis of Chronic Myeloid Leukemia (CML) Clones Reveals Heightened BCR-ABL1 Genetic Instability and Wild-Type BCR-ABL1 Exhaustion in Patients Failing Sequential Imatinib and Dasatinib Therapy.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 1938-1938 ◽  
Author(s):  
Alfonso Quintás-Cardama ◽  
Don L. Gibbons ◽  
Hagop Kantarjian ◽  
Moshe Talpaz ◽  
Nick Donato ◽  
...  
Keyword(s):  
Amino Acid ◽  
Genetic Instability ◽  
Kinase Inhibitors ◽  
Mutational Analysis ◽  
Direct Sequencing ◽  
Cytogenetic Response ◽  
Kinase Domain ◽  
Wild Type ◽  
Abl Kinase ◽  
Tki Resistance

Abstract ABL kinase domain (AKD) mutations are the main mechanism of resistance in patients (pts) with CML who fail tyrosine kinase inhibitors (TKIs) therapy, being found in 20%–40% of cases by direct sequencing (DS). Therefore, many pts fail TKI therapy for unknown reasons. We evaluated the development of AKD mutations among 61 CML pts after imatinib-intolerance (n=10) or -resistance (n=51) enrolled in a phase I study of dasatinib by DS of nested PCR-amplified BCR-ABL1 products as well as by DNA expansion of specific clones (DESC) followed by DNA sequencing of at least 10 clones. Prior to imatinib (400 mg daily in 47, 600 in 13, and 800 in 1), 54 pts were in chronic (CP), 2 in accelerated (AP), and 5 in blastic (BP) phase. At the end of imatinib therapy, 26 pts were in CP, 14 in AP, and 21 in BP. AKD mutations (in ≥1 out of 10 sequenced clones) were detected in 58/61 (95%) pts by DESC (4 pts with wild type [WT] BCR-ABL1) but only in 23/55 (42%) by DS. Overall, 118 AKD mutations at 112 amino acid positions were detected by DESC, of which 77 had never been previously reported. Mutations conferring resistance to >1μM imatinib (M244V, G250E, Q252H, Y253H, E255K/V, F359V, H396R, and T315I) were detected in 20 (34%) pts by DESC, but only in 5 (8%) by DS. Combinations of mutations within the same clone (polymutants) were detected in 33/58 (57%) pts by DESC, with clones expressing 2 (n=41), 3 (n=11), 4 (n=1), or even 5 (n=2) distinct mutations. By contrast, only 1 pt was found to carry 2 different mutations (M244V and M351T) by DS. Dasatinib was subsequently given to 56/61 (92%) pts (53 evaluable for response) for a median of 17 months (range, 1 to 48). DESC available in 15 pts during dasatinib therapy revealed 16 additional mutations (15 amino acid positions), including 5 previously not reported (all in polymutants). Dasatinib-resistant mutations (L248V/R, Q252H, E255K, V299L, T315I/A, and F317L/C/I/S/V) were detected in 7/15 (47%) cases (2 with T315I) by DESC but only in 2/15 (13%) by DS. Of these 15 pts, only 3 (1 CP, 1 AP, and 1 BP) are alive. The proportion of clones harboring WT BCR-ABL1 prior to and during dasatinib therapy decreased significantly (p=0.003), particularly in pts harboring highly dasatinib-resistant mutants. Notably, pts without cytogenetic (CG) response on dasatinib had a lower proportion of WT clones compared with those who achieved at least a partial cytogenetic response (p=0.02). AFTER IMATINIB ON DASATINIB Evaluable Patients No. Clones No. WT Clones (%) Evaluable Patients No. Clones No. WT Clones (%) DASATINIB RESPONSE 53 598 268 (48) 15 130 26 (20) No CG Response 25 242 128 (49) 7 58 5 (9) CG Response Minor 10 79 33 (42) 4 35 9 (26) Partial 6 57 35 (61) 2 18 8 (44) Complete 12 123 46 (37) 2 19 4 (21) In summary, DESC greatly increases the sensitivity of detection of AKD mutants compared to DS and reveals heightened BCR-ABL1 genetic instability among pts failing TKIs, which could explain TKI resistance in pts not carrying resistant mutations by DS. This might be mediated by generation of resistant polymutant clones that perpetuate a “mutator phenotype” leading to WT BCR-ABL1 exhaustion.

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