Identification of Three Novel Frameshift Mutations in the PKD1 Gene in Iranian Families with Autosomal Dominant Polycystic Kidney Disease Using Efficient Targeted Next-Generation Sequencing.

BACKGROUND/AIMS: Autosomal dominant polycystic kidney disease (ADPKD) is one of the most common inherited cystic kidney diseases caused by mutations in two large multi-exon genes, PKD1 and PKD2. High allelic heterogeneity and duplication of PKD1 exons 1-32 as six pseudo genes on chromosome 16 complicate molecular analysis of this disease. METHODS: We applied targeted next-generation sequencing (NGS) in 9 non-consanguineous unrelated Iranian families with ADPKD to identify the genes hosting disease-causing mutations. This approach was confirmed by Sanger sequencing. RESULTS: Here, we determined three different novel frameshift mutations and four previously reported nonsense mutations in the PKD1 gene encoding polycystin1 in heterozygotes. CONCLUSION: This study demonstrates the effectiveness of NGS in significantly reducing the cost and time for simultaneous sequence analysis of PKD1 and PKD2, simplifying the genetic diagnostics of ADPKD. Although a probable correlation between the mutation types and phenotypic outcome is possible, however for more extensive studies in future, the consideration of renal hypouricemia (RHUC) and PKD1 coexistence may be helpful. The novel frameshift mutations reported by this study are p. Q1997X, P. D73X and p. V336X.

Mutational Screening of PKD1 and PKD2 Genes in Iranian Population Diagnosed with Autosomal Dominant Polycystic Kidney Disease.

BACKGROUND: Autosomal Dominant Polycystic Kidney Disease (ADPKD) is the fourth most frequent cause of endstage renal disease (ESDR), occurring at a varying frequency of 1/400 to 1/800 persons. The disease affects all ethnic groups worldwide, and there is a need for population based studies to be carried out for better diagnostic, genetic counselling, and treatment purpose. METHODS: Eighteen unrelated probands (10 males and 8 females) with a familial history of ADPKD were selected for the study. Their clinical evaluation was performed to diagnose and assess disease progression. PKD1 and PKD2 genes were genotyped in each proband by next generation sequencing (NGS). RESULTS: Mutational analysis of PKD1 and PKD2 genes using NGS in eighteen unrelated Iranian ADPKD families revealed a total of eighteen heterozygous variations. PKD1 genotype revealed eight frameshift deletion mutations, two frameshift insertion mutations, five nonsense mutations and one splice mutation and PKD2 showed one frameshift deletion mutation and one frameshift insertion mutation. Four of the variants reported were novel and were present in the PKD1 gene. Further, PKD1 truncating mutations reached ESRD earlier than patients with non-truncating PKD1 mutations (52 ± 3.2 years vs. 58 ± 10.8 years, p = 0.01). CONCLUSIONS: The PKD1 and PKD2 genotyping of ADPKD Iranian patients with familial history showed no mutational hotspot. The screening has given four novel variants that will contribute to diagnosis, genetic counselling, and treatment of ADPKD patients in general.

A common variant in the adiponectin gene and polycystic ovary syndrome risk.

In this study, we explored whether polymorphisms in insulin receptor (INSR), adiponectin (ADIPOQ), parathyroid hormone (PTH), and vitamin D receptor (VDR) genes are associated with polycystic ovary syndrome (PCOS). A total of 362 subjects, including 181 women with PCOS and 181 controls were enrolled in this case-control study. Two SNPs (rs2059806 and rs1799817) in the INSR gene, two SNPs (rs2241766 and rs1501299) in the ADIPOQ gene, one SNP (rs6256) in the PTH gene, and one SNP (rs757343) in the VDR gene were analyzed using PCR-RFLP method. We observed no significant difference in genotype and allele frequencies between the women with PCOS and controls for the rs2059806, rs1799817, rs1501299, rs6256, and rs757343 polymorphisms either before or after adjustment for confounding factors including age and BMI. However, the ADIPOQ rs2241766 "TT" genotype compared with "TG and GG" genotypes was associated with a 1.93-fold increased risk for PCOS (P = 0.006, OR = 1.93, 95% CI = 1.20-3.11), and the differences remained significant after adjustment for age and BMI (P = 0.039, OR = 1.72, 95% CI = 1.03-2.86). Furthermore, the ADIPOQ rs2241766 "T" allele was significantly overrepresented in women with PCOS than controls (P = 0.006; OR = 1.80, 95% CI = 1.18-2.70), and the difference remained significant after Bonferroni correction. Our findings suggest that the ADIPOQ rs2241766 "TT" genotype is a marker of increased PCOS susceptibility. This study also indicates for the first time that there are no significant association between INSR rs2059806, PTH rs6256, and VDR rs757343 gene polymorphisms and PCOS risk. However, these data remain to be confirmed in larger studies and in other populations.

Influence of gene variants related to calcium homeostasis on biochemical parameters of women with polycystic ovary syndrome.

PURPOSE: The purpose of this study was to evaluate the associations between polymorphisms in vitamin D receptor (VDR), parathyroid hormone (PTH), calcium sensing receptor (CASR), insulin receptor (INSR), and adiponectin (ADIPOQ) genes and biochemical characteristics of women with polycystic ovary syndrome (PCOS). METHODS: Serum levels of LH, FSH, estradiol, testosterone, prolactin, SHBG, glucose, IGF-1, IGFBP-1, calcium, phosphorus, PTH, 25(OH)D, and 1,25(OH)(2) D were measured in 56 women with PCOS. Furthermore, genotyping five, one, one, two, and two polymorphisms of the VDR, PTH, CASR, INSR, and ADIPOQ genes, respectively, were performed. RESULTS: The VDR TaqI "CC" genotype was associated with elevated serum levels of LH (p = 0.011). There were significant associations between decreased levels of SHBG and both VDR BsmI "GG" (p = 0.009) and ADIPOQ BsmI "CC" (p = 0.016) genotypes. Furthermore, patients with CaSR Hin1I "TG" genotype showed higher HoMA-IR (p = 0.008). All these associations remained significant after Bonferroni correction. In addition, phosphorus correlated negatively with estradiol (r = -0.298, P = 0.026) and positively with glucose (r = 0.287, P = 0.032). CONCLUSIONS: These data indicated for the first time that it is possible that the VDR and CASR gene variants through their effects on LH and SHBG levels, and insulin resistance are involved in pathogenesis of PCOS.

Co-segregation of candidate polymorphism rs201204878 of the PKD1 gene in a large Iranian family with autosomal dominant polycystic disease.

Autosomal dominant polycystic kidney disease (ADPKD) is the fourth most common cause of end-stage renal disease, occurring at a frequency of 1 in 400 to 1 in 800 individuals among different populations. The disease affects all ethnic groups worldwide, and there is a requirement for population-based studies to be conducted in order to improve diagnosis, genetic counseling and treatment. A large Iranian family with ADPKD was recruited for the current study. Clinical evaluation was performed to diagnose and assess disease progression in 11 members of this family, including 7 affected members and 4 unaffected members. PKD1 and PKD2 genes were genotyped in subjects by next-generation sequencing (NGS). Mutational analysis of PKD1 and PKD2 genes in this family revealed three intronic variations and three synonymous exonic variants in the PKD2 gene, and two non-synonymous exonic variants and eight intronic variants in PKD1, resulting in a total of 16 heterozygous variations among these two genes. Among the 16 variations, all except three intronic variants in the PKD1 gene have already reported in the Iranian population. The three novel mutations were predicted to be deleterious polymorphisms using in silico methods. Among the reported intronic variations, rs201204878 was identified as a splice region variant, leading to truncation of the polycystin-1 protein. In conclusion, genotyping of PKD1 and PKD2 in this family with ADPKD revealed no mutational hot spots. However, genetic screening identified three novel variants in the Iranian population. The data generated in the present study will contribute to improving the diagnosis, genetic counseling and treatment of patients with ADPKD.