Yang et al. BMC Genomics (2017) 18:982 DOI 10.1186/s12864-017-4247-8 RESEARCHARTICLE Open Access PDE1A polymorphism contributes to the susceptibility of nephrolithiasis Zhenxing Yang1†, Tao Zhou1†, Bishao Sun1, Qingqing Wang1, Xingyou Dong1, Xiaoyan Hu1, Jiangfan Zhong1,3, Bo Song2 and Longkun Li1,3* Abstract Background: Previous studies have confirmed a family risk of nephrolithiasis (NL), but only 15% of all cases are associated with an identified monogenic factor. In clinical practice, our group encountered a patient with NL combined with cystic kidney disease that had 3 affected family members. No known mutations association with NL was detected in this family, and thus further investigation of the molecular cause of NL was deemed to be necessary. Results: Quality analysis from the sequencing stage showed a more than 80-fold average depth and 95% coverage for each sample, and six mutations within six genes were chosen as candidate variants for further validation. Genotyping of rs182089527in the phosphodiesterase 1A (PDE1A) gene in the validation cohort indicated that the alternative allele was present in 15 patients with heterozygosity and in 1 patient with homozygosity, and exhibited significant enrichment in NL patients (Fisher’s exact test, adjusted p = 0.0042) and kidney cystic patients (Fisher’s exact test, adjusted p = 0.067) compared to controls. In addition, function analysis displayed a significant decrease in the protein and mRNA expression levels resulting from the rs182089527 mutant sequence compared with the wild-type sequence. Moreover, patients with this mutation displayed a high level of creatinine and urea in urinalysis. Conclusions: Our study provides genetic evidence that the rs182089527 mutation in PDE1A is involved in the development of NL and kidney cysts, which should help to improve personalized medicine for diagnosis and treatment. Keywords: PDE1A, Nephrolithiasis, Polymorphism Background different between northern (4.1%) and southern Nephrolithiasis (NL), also known as kidney stones, is regions (4.0%) [2]. Both genetic and environmental a common disease associated with major morbidity factors contribute to the risk of NL. In a genetic because of colicky pain, the necessity of surgical pro- epidemiology follow-up investigation of a cohort of cedures, and even acute renal failure [1]. The esti- 37,999 male participants, the relative risk of the mated life time prevalence of NL is about 1–15% incidence of stone formation in men with a positive worldwide, which varies according to age, gender, family history was 2.75 (95% confidence inter- race, and geographic location. In China, the overall val = 2.19–3.12) [3].A twin study in Vietnam indi- prevalence rate was estimated to be 4.0% (4.8% in cated that the proband concordance rate in men and 3.0% in women), and the prevalence was monozygotic twins (32.4%) was significantly greater than the rate in dizygotic twins (17.3%), and the estimated heritability of the risk for NL was 56%. * Correspondence: [email protected] †Equal contributors The genetic cause of NL is complicated, ranging from the 1Department of Urology, Second Affiliated Hospital, Third Military Medical rare monogenic to the more common polygenic forms. To University, Chongqing, People’s Republic of China date, at least 30 genes have been reported to be associated 3Ostrow School of Dentistry and Department of Pediatrics, School of Medicine, University of Southern California, Los Angeles, CA, USA with Mendelian forms of NL or nephrocalcinosis by Full list of author information is available at the end of the article autosomal-recessive, autosomal-dominant, or X-linked © The Author(s). 2017 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. Yang et al. BMC Genomics (2017) 18:982 Page 2 of 8 transmission [4, 5].Several renal calcium stone-related Therefore, to further explore the potential causal disorders are known to be monogenic, such as Dent disease genes, we employed whole-exome sequencing technol- (Online Mendelian Inheritance in Man [OMIM 300009]), ogy of blood samples from 10 family members (4 af- Bartter’s syndrome, idiopathic hypercalciuria, primary distal fected and 6 unaffected) and 2307 validation samples renal tubular acidosis, hypophosphatemic rickets with hyper- (including 993 NL patients and 1314 controls, 328 calciuria, familial hypomagnesemia with hypercalciuria and kidney cystic patients and 622 controls) to investigate nephrocalcinosis, primary hyperoxaluria, cystinuria, renal the causal mutations, and postulated that NL may be hypouricemia, and hypocalciurichypercalcemia [6], but only a monogenic disease. Following functional validation about 15% of 272 genetically unrelated individuals were was conducted using RT-PCR and western blot. shown to have single-gene disease which have mentioned above [7]. With the development of microarray technology, Methods genome-wide association studies have also been employed to Sample collection investigate the susceptibility genes of NL. One such study Proband and nephrolithiasis family description conducted by Gudmar et al. [8] identified common, syn- A elder man presented with post-polio syndrome of onymous variants in the CLDN14 gene that were associated right foot claudication,20 years history of renal calculi, with kidney stones, and homozygous carriers of the single repeated bilateral back pain, urgent micturition, nucleotide polymorphism (SNP) rs219780[C] in CLDN14 hematuria and dysuria. The patient suffered from hyper- were estimated to have a 1.64-times greater risk of develop- tension almost 10 years, admitted oral antihypertensive ing the disease compared to non-carriers. Another study drugs, and also complained with intermittent voiding conducted in Japan found three novel loci for NL and stones in urine 3 times, but was not treated. He had revealed the association of SNP rs11746443 (upstream of the noticed with aggravation of back pain and voiding stones SLC34A1 gene) with the reduction of estimated glomerular in urine again 1 month ago, which make them admitted filtration rate [9]. Although dozens of susceptibility genes to our Urology Department. Physical examination have been reported, in-depth analysis of the monogenic revealed a temperature of 36.3 °C, pulse of 102, blood causes of NL is still necessary. pressure (BP) of 109/88 mmHg, left flank tenderness With the advent of next-generation sequencing, the and a palpable left kidney but was otherwise normal. mutation analysis of Mendelian genes has not only Laboratory testing indicated that creatinine concentra- become technically available but is also cost-effective. In tion was 89.9 umol/L, the serum calcium was clinical practice, our group encountered a family affected 2.26 mmol/L, uric acid was357 umol/L, serum by NL (Fig. 1), with four family members affected. phosphorus was 1.06 mmol/L, and serum magnesium Proband DNA samples were collected and sequenced was 0.78 mmol/L. The serum electrolytes were within initially, but no known association mutation of NL was normal limits. Urinalysis showed specific gravity of 1.02, detected. PH 6.5, no protein, and 6 to 10 white blood cells and red In addition, renal cysts are extremely common and blood cells (RBCs) per high-power field without casts or are present in more than one third of NL patients crystals. Abdominal ultrasound showed multiple cystic older than 50 years. More importantly, NL shows a dark areas with the maximum diameter of 2.2 cm, clear common complication of kidney cyst development. boundaries and regular morphology. Ultrasonography and Fig. 1 A pedigree of nephrolithiasis family with affected patients (blackened symbols) and PDE1A gene mutation which located in chr2:183,106,640. Symbols with question mark denote family members who are probably affected. Circles represent female family members, squares represent male family members,and crosses represent dead family members. Wilde-type and mutant-type are marked by a plus sign (+) and a minus sign (−). Arrows indicate probands Yang et al. BMC Genomics (2017) 18:982 Page 3 of 8 computed tomography (CT) of left kidney demon- product. The size selectedproduct was PCR amplified, strated hydronephrosis, no marked parenchymal and the final product was validated using the Agilent atrophy, and multiple stones in therenal pelvis. There Bioanalyzer. Two steps of hybridization and wash were was a cystic dark area, diameter of 1.1 cm, in right needed for construction. PCR was used in order to amp- kidney with regular morphology and clear boundary lify the enriched DNA library for sequencing. PCR was (Additional file 1: Figure S1).The patient has endured performed with the same PCR primer cocktail used in family history of nephrolithiasis (Fig. 1). TruSeq DNA Sample Preparation. Axeq Technologies performs procedures for quality control analysis on the Cohort samples sample library and quantification of the DNA library Nine hundred ninety three cases of nephrolithiasis templates. Illumina utilizes a unique “bridged” amplifica- (NL) and 1314