Mutation analysis and phenotypic investigation in patients with primary distal renal tubular acidosis / 中华肾脏病杂志

Objective:To analyze the gene variants in patients with primary distal renal tubular acidosis (dRTA), and explore the correlation between the genotype and phenotype.Methods:The Sanger direct sequencing or whole-exome sequencing was used to identify causal variants and the variation pathogenicity was evaluated according to 2015 American College of Medical Genetics and Genomics (ACMG) standards and guidelines in 44 dRTA patients (37 families) diagnosed in the Affiliated Qingdao Municipal Hospital of Qingdao University and the Affiliated Hospital of Qingdao University from April 2010 to September 2020. The clinical features of the patients were summarized, and the correlation between the genotype and phenotype was investigated.Results:Seven variants of SLC4A1 gene, 17 variants of ATP6V0A4 gene, and 15 variants of ATP6V1B1 gene were identified in 44 patients with dRTA, and of which 11 variants were new ones. According to ACMG guidelines, the pathogenic, likely pathogenic, benign variants among the 39 variants were 22, 16 and 1, respectively. Nine patients were autosomal dominant hereditary dRTA caused by SLC4A1 gene mutation, 4 patients with autosomal recessive hereditary dRTA complicated with Southeast Asian ovalocytosis and anemia were caused by SLC4A1 gene mutation, and 14 patients caused by ATP6V0A4 gene mutation and 8 patients caused by ATP6V1B1 gene mutation were autosomal recessive hereditary dRTA; Two children with dRTA were found to carry one monoallelic defect in ATP6V1B1, and no causal gene mutation was identified in 7 patients. One patient showed incomplete dRTA, and the other 43 patients showed complete dRTA. The prevalence of sensory neural hearing loss caused by ATP6V0A4 and ATP6V1B1 mutation were 2/14 and 6/10 respectively. The frequency of chronic kidney disease in adults, children and infants were 4/4, 2/4, and 1/36, separately. After the drug treatment based on potassium citrate and sodium citrate, the growth and development (28/40) and electrolyte disturbance (41/44) of most patients were significantly improved. Conclusions:The present study has identified 39 variants of SLC4A1, ATP6V0A4 and ATP6V1B1 genes in 44 patients with dRTA, including 11 novel ones. There is a close relationship between genotype and phenotype in dRTA patients and most patients' conditions were improved after proper treatment. This study enriches the human gene mutation database and provides valuable references for diagnosis, treatment and genetic counseling in patients with dRTA.

Mutation analysis of KCNJ1 gene and investigation of phenotype in 5 Chinese patients with Bartter syndrome type 2 / 中华肾脏病杂志

Objective@#To identify and analyze the variants of the KCNJ1 gene in five Chinese patients with Bartter syndrome type 2 (BS2), and to describe their clinical features as well as treatment results.@*Methods@#Data and blood samples of five BS2 patients and their relatives confirmed by Qingdao Municipal Hospital from June 2012 to January 2019 were collected. Whole-exome-sequencing (WES) based on the second generation high throughput sequencing was performed to detect variants. The 2015 American College of Medical Genetics and Genomics Standards and Guidelines were applied to analyze the pathogenicity of the variants. The clinical features and laboratory results were retrospectively studied. The response to treatment and follow-up data were reviewed.@*Results@#Ten variants including six novel ones of KCNJ1 gene were identified through WES and verified by Sanger dideoxy sequencing. Missense variants accounted for the highest proportion. The common symptoms and signs of five BS2 patients from high to low incidence were polydipsia and polyuria (5/5), one of them (1/5) presented with diabetes insipidus; maternal polyhydramnios and premature delivery (4/5); growth retardation (3/5). Initially, two patients presented with hypochloremic metabolic alkalosis and hypokalemia, whereas the acid-base disturbance was absent in the others. One patient experienced hyperkalemia. In terms of calcium-phosphorus metabolism, one patient had evident parathyroid hormone (PTH) resistance (hypocalcemia, hyperphosphatemia and markedly elevated serum intact PTH levels), three presented with PTH overacting (hypercalcemia, hypophosphatemia and mild elevated serum intact PTH levels), and one showed normal blood calcium and phosphorus concentrations with high-normal serum intact PTH levels. All patients had nephrocalcinosis or hypercalciuria, and one of them complicated with nephrolithiasis. Indomethacin helped to correct the growth retardation, halt polydipsia polyuria, decrease the elevated urinary calcium excretion, and normalize electrolyte disturbance as well as PTH parameters in some patients.@*Conclusions@#This investigation identifies ten variants of KCNJ1 gene, including six ones that have not been previously reported, which will enrich the human gene mutation database (HGMD). These patients in our study have atypical BS phenotype, so that careful differentiation from other parathyroid diseases will be required for clinicians.

Mutation analysis of KCNJ1 gene and investigation of phenotype in 5 Chinese patients with Bartter syndrome type 2 / 中华肾脏病杂志

Objective:To identify and analyze the variants of the KCNJ1 gene in five Chinese patients with Bartter syndrome type 2 (BS2), and to describe their clinical features as well as treatment results. Methods:Data and blood samples of five BS2 patients and their relatives confirmed by Qingdao Municipal Hospital from June 2012 to January 2019 were collected. Whole-exome-sequencing (WES) based on the second generation high throughput sequencing was performed to detect variants. The 2015 American College of Medical Genetics and Genomics Standards and Guidelines were applied to analyze the pathogenicity of the variants. The clinical features and laboratory results were retrospectively studied. The response to treatment and follow-up data were reviewed.Results:Ten variants including six novel ones of KCNJ1 gene were identified through WES and verified by Sanger dideoxy sequencing. Missense variants accounted for the highest proportion. The common symptoms and signs of five BS2 patients from high to low incidence were polydipsia and polyuria (5/5), one of them (1/5) presented with diabetes insipidus; maternal polyhydramnios and premature delivery (4/5); growth retardation (3/5). Initially, two patients presented with hypochloremic metabolic alkalosis and hypokalemia, whereas the acid-base disturbance was absent in the others. One patient experienced hyperkalemia. In terms of calcium-phosphorus metabolism, one patient had evident parathyroid hormone (PTH) resistance (hypocalcemia, hyperphosphatemia and markedly elevated serum intact PTH levels), three presented with PTH overacting (hypercalcemia, hypophosphatemia and mild elevated serum intact PTH levels), and one showed normal blood calcium and phosphorus concentrations with high-normal serum intact PTH levels. All patients had nephrocalcinosis or hypercalciuria, and one of them complicated with nephrolithiasis. Indomethacin helped to correct the growth retardation, halt polydipsia polyuria, decrease the elevated urinary calcium excretion, and normalize electrolyte disturbance as well as PTH parameters in some patients. Conclusions:This investigation identifies ten variants of KCNJ1 gene, including six ones that have not been previously reported, which will enrich the human gene mutation database (HGMD). These patients in our study have atypical BS phenotype, so that careful differentiation from other parathyroid diseases will be required for clinicians.

Mutation analysis of SLC5A2 gene and determination of the renal threshold for glucose excretion in Chinese patients with familial renal glucosuria / 中华肾脏病杂志

Objective To analyze and identify the mutations in SGLT2 gene of nine Chinese families with FRG, and determine the renal threshold for glucose excretion (RTG), so as to explore the association of genotype and RTG. Methods All coding regions of SGLT2 gene, including intron exon boundaries, were analyzed using PCR followed by direct sequence analysis. Quantitative test for 24?hour urine glucose and RTG were measured among 9 probands (21 patients) and their family members from 9 pedigrees (total 25 subjects). The differences in renal glucose thresholds between patients with different genotypes (heterozygotes and compound heterozygotes; c.886(-10_-31) del heterozygotes and other heterozygotes) were compared. Results Twelve mutations were identified by SGLT2 gene analysis, including 10 novel ones that were not included in HGMD:c.331T>C, p.W111R;c.374T>C, p.M125T; c.394C>T, p.R132C; c.612G>C, p.Q204H; c.829C>T, p.P277S; c.880G>A, p.D294N;c.1129G>A, p.G377S; c.1194C>A, p.F398L; c.1540C>T, p.P514S; c.1573C>T, p.H525Y. In thisstudy, the mutation c.886(-10_-31)del that is specific to Chinese population accounted for about 28％of the total alleles (5/18). The RTG values of patients with compound heterozygous mutations were much lower than those with simple heterozygous mutations [(1.28 ±0.10) vs (5.14±0.77) mmol/L; P<0.001];and c.886(-10_-31)del heterozygotes had significant lower RTG values than others [(4.43 ± 0.37) vs (5.70 ± 0.51) mmol/L, P<0.001]. Conclusions Ten novel mutations which may be related to FRG are found in this study, and c.886(-10-31)del may be a hot?spot mutation in Chinese patients. Compound heterozygotes had much lower RTG values than simple heterozygotes.

Mutation analysis of SLC12A1 gene in nine Chinese patients with Bartter syndrome type Ⅰ / 中华肾脏病杂志

Objective To analyze the mutations of SLC12A1 gene in nine Chinese families with Bartter syndrome type I (BS1),and analyze the relationship between genotype and phenotype.Methods The next generation sequencing was used to detect mutations in nine BS1 patients including eight with antenatal BS (aBS) and one with classical BS (cBS).Clinical characteristics and biochemical findings at the first admission as well as follow-up were reviewed.Results 15 different mutations of SLC12A1 gene were identified,including 11 novel ones.Among nine probands,seven were compound heterozygotes,two were homozygotes.All patients presented with polydipsia and polyuria,and eight with growth retardation.All patients had lower than-normal serum chloride concentration,metabolic alkalosis,and elevated basal renin activity and aldosterone,and seven had hypokalemia.Through treatment of indomethacin and/or potassium chloride,biochemical indicators could roughly restored normal.Conclusion These findings will enrich the human gene mutation database (HGMD) and provide valuable references to the genetic counseling and diagnosis for Chinese population.

Mutation analysis of 5 children with primary distal renal tubular acidosis / 中华肾脏病杂志

Objective To analyze the mutations of causal genes in 5 children with primary distal renal tubular acidosis (dRTA),and explore their association of genotype and phenotype,so as to raise the awareness of the disease.Methods The whole exome sequencing was used to identify mutations in these 5 children from 5 families.Results A total of 4 different mutations of ATP6V0A4 gene were found in 2 dRTA children,including a novel heterozygous intron mutation (c.639 + 1G＞ A),a reported heterozygous nonsense variant (c.580C ＞T,p.Arg194*) and 2 novel heterozygous duplications (c.1504dupT,p.Tyr502Leufs*22;c.2351dupT,p.Phe785Ilefs*28).Two novel heterozygous missense mutations of ATP6V 1B 1 gene (c.409C ＞ T,p.Pro 137Ser;c.904C ＞ T,p.Arg302Trp) were identified in the third child,and a heterozygous missense mutation of SLC4A1 gene (c.1765C ＞ A,p.Arg589Ser) previously reported was found in the fourth child.No mutation of the dRTA-related causal genes was found in the fifth child.Furthermore,the mutations of causal genes in each of the first three children were compound heterozygous,which were consistent with the autosomal recessive inheritance pattern,and the variant from the fourth child was de novo.Conclusions The present study has found 7 mutations,including 5 novel variants,which enriches the human gene mutation database (HGMD) and contributes to a better understanding of the disease mechanisms.

Comparison of the etiological constitution of two and three or more recurrent miscarriage / 中华妇产科杂志

Objective To compare the etiological constitution of recurrent miscarriage (RM) between patients with consecutive two and three or more miscarriages through combining the routine examination results and embryonic karyotype. Methods Patients with a history of two or more consecutive clinical miscarriages(≤12 weeks of gestation)consulting in the RM clinic of the First Affiliated Hospital of Sun Yat-sen University from March 2011 to January 2016 were collected. Six hundred and ninety-six with detailed history recorded, routine clinical examinations of RM and at least once embryonic karyotype were ultimately enrolled in this study. Their etiological constitution of RM were analyzed in groups of consecutive two and three or more miscarriage. The etiologies of RM in analysis consisted of women age, body mass index (BMI), chromosome abnormalities of couples, uterine abnormalities, endocrinology abnormalities and antiphospholipid syndrome(APS). Results (1)Among 696 patients, the abnormal embryonic karyotypes was 60.6%(422/696)and routine RM etiologies was 32.2%(224/696), leaving the ratio of unexplained RM was only 29.0%(202/696).(2)A total of 717 embryo karyotype were found in 696 patients, included 21 cases with twice embryo karyotype results the percentage of normal embryo was 39.7%(285/717), while abnormal ones was 60.3%(432/717). Among the types of abnormal karyotype, the most common ones (>10%)were trisomy 16(19.2%, 83/432), monosome X(11.3%, 49/432)and trisomy 22(10.9%, 47/432). (3)Among the 696 RM patients, the number of two and three or more miscarriages were respectively 446(64.1%,446/696)and 250(35.9%,250/696). Comparing groups of three or more miscarriages with two miscarriages, there were significant differencein older age as well as uterine adhesion(P<0.05). But no difference was found in body mass index(BMI), the rates of chromosome abnormalities of couples, uterine abnormalities except uterine adhesion, endocrinology abnormalities and APS (all P>0.05) between two groups. Conclusions The abnormal embryonic karyotype is the most common cause of first-trimester RM. The etiological constitution of two and three or more recurrent miscarriages is accordant, suggesting that routine clinical examination and the embryonic karyotype should be started following two consecutive clinical early miscarriages.

Mutation analysis of an adult patient with fructose-1,6-bisphosphatase deficiency in a Chinese family / 中华内分泌代谢杂志

The gene mutations of a patient with fructose-1,6-bisphosphatase (FBPase) deficiency and her parents were analyzed and her clinical manifestations, laboratory tests, and genetic characteristics were reviewed. The molecular analysis of FBP1 gene showed a G residue duplication at base 960 in exon 7(c. 960dupG) in this patient while her parents carried the heterozygous c. 960dupG mutation. The prominent clinical feature of this patient was the benign course of the disease with age. However, acute attack could be triggered by stress, long-time fasting, a large amounts of fructose intake, etc. The typical clinical manifestations were severe lactic acidosis, hypoglycemia, and elevated liver enzymes.

Mutation analysis of an adult patient with fructose-1,6-bisphosphatase deficiency in a Chinese family / 中华内分泌代谢杂志

The gene mutations of a patient with fructose-1,6-bisphosphatase (FBPase) deficiency and her parents were analyzed and her clinical manifestations, laboratory tests, and genetic characteristics were reviewed. The molecular analysis of FBP1 gene showed a G residue duplication at base 960 in exon 7(c. 960dupG) in this patient while her parents carried the heterozygous c. 960dupG mutation. The prominent clinical feature of this patient was the benign course of the disease with age. However, acute attack could be triggered by stress, long-time fasting, a large amounts of fructose intake, etc. The typical clinical manifestations were severe lactic acidosis, hypoglycemia, and elevated liver enzymes.