Phenotype-Driven Next-Generation Sequencing and Structure-Based In Silico Analysis Reveal Disease-Specific Diagnostic Yield and Genotype-Phenotype Correlations in Inherited Kidney Diseases.

To review cases of couples presented to our PGT-unit with copy number variants (CNVs) classified as variants of uncertain significance (VUS) in order to better understand their needs. Retrospective cohort study conducted in a tertiary medical-center, 2014-2019. We reviewed files of all couples applying for genetic counseling with CNVs classified as VUS. The main outcomes measured: number of VUS findings and their description, PGT-M procedures planned and performed, IVF cycles, clinical pregnancy, and live birth rates (LBR). VUS were classified according to the American-College of Medical-Genetics and Genomics classification at time of first consultation, and updated-December 2018. Twenty-four couples presented with a total of 30 VUS. Twelve couples (50%) had isolated VUS and 12 (50%) had VUS diagnosed in addition to a pathogenic mutation. Initially, nine findings (30%) were defined as VUS; eight (27%) as likely benign (b-VUS); and 13 (43%) as likely pathogenic (p-VUS). PGT-M was recommended for 17/30 CNVs (56.6%), 12 (70%) of which, isolated VUS. No couple had other indications for IVF. To date, nine couples performed PGT-M for isolated VUS; LBR per-couple-55.5%. Five couples performed PGT-M for both pathogenic findings and VUS, LBR-80%. After reviewing VUS classifications, 30% remained unchanged, 20% were more severely defined, and 50% less severely defined. The genomic era enables detection of VUS whose definition is subject to change as additional information becomes available. The uncertainty of variants' clinical significance and changes in VUS definition over time complicates genetic counseling. Revised guidelines for VUS interpretation and reevaluation of patient counseling before each pregnancy must be practiced when counseling them regarding the justification of PGT-M for their diagnosed VUS.

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BackgroundCongenital nephrotic syndrome of the Finnish type (CNF) is an autosomal recessive disorder resulting from mutations in the NPHS1 gene, which encodes nephrin, an essential protein in the podocyte slit diaphragm. Pathogenic mutations of NPHS1 cause substantial proteinuria detectable at birth. Variants of uncertain significance (VUS) are recognized mutations, but their effects on health are not yet understood. This uncertainty makes it challenging to identify specific types of VUS that may contribute to disease development. The association of CNF with NPHS1 VUS remains unclear.Case DescriptionWe describe the salient features of a newborn with CNF and multiple fetal anomalies based on clinical risk factors discovered by ultrasound (US) and X-rays, which include cardiomegaly, polycystic kidney disease, and renal dysplasia. Biochemical tests showed substantial proteinuria and excess protein in the urine detected at birth; this condition caused albuminuria, hypoalbuminemia, edema, and additional symptoms. The patient underwent treatment to reduce the risks of proteinuria, hypertension, infection, and other symptoms. The next generation sequencing (NGS) analysis revealed that the infant had five previously unreported heterozygous missense variants classified as VUS in NPHS1, NUP160, ALG1, and CRB2. The NPHS1 c.2150A>G and CRB2 c.1654G>T may lead to defects in the CTCF (CCCTC binding factor) and exonic splicing enhancer (ESE) motifs, respectively, which could account for the observed clinical features in the newborn.ConclusionsThe infant’s illness may be related to changes in exonic splicing caused by NPHS1-VUS and CRB2-VUS. NPHS1 encodes the nephrin protein, which is crucial for the slit diaphragm of podocytes, while CRB2 is essential for slit diaphragm formation and is linked to cystic kidney disease.

Epilepsy is one of the most common and disabling neurological disorders. It is highly prevalent in children with neurodevelopmental delay and syndromic diseases. However, epilepsy can also be the only disease-determining symptom. The exact molecular diagnosis is essential to determine prognosis, comorbidity, and probability of recurrence, and to inform therapeutic decisions. Here, we describe a prospective cohort study of patients with epilepsy evaluated in seven diagnostic outpatient centers in Germany. Over a period of 2 months, 07/2022 through 08/2022, 304 patients (317 returned result) with seizure-related human phenotype ontology (HPO) were analyzed. Evaluated data included molecular results, phenotype (syndromic and non-syndromic), and sequencing methods. Single exome sequencing (SE) was applied in half of all patients, followed by panel (P) testing (36%) and trio exome sequencing (TE) (14%). Overall, a pathogenic variant (PV) (ACMG cl. 4/5) was identified in 22%; furthermore, a significant number of patients (12%) carried a reported clinically meaningful variant of unknown significance (VUS). The average diagnostic yield in patients ≤ 12 y was higher compared to patients >12 y cf. Figure 2B vs. Figure 3B. This effect was more pronounced in cases, where TE was applied in patients ≤ 12 vs. >12 y [PV (PV + VUS): patients ≤ 12 y: 35% (47%), patients > 12 y: 20% (40%)]. The highest diagnostic yield was achieved by TE in syndromic patients within the age group ≤ 12 y (ACMG classes 4/5 40%). In addition, TE vs. SE had a tendency to result in less VUS in patients ≤ 12 y [SE: 19% (22/117) VUS; TE: 17% (6/36) VUS] but not in patients >12 y [SE: 19% (8/42) VUS; TE: 20% (2/10) VUS]. Finally, diagnostic findings in patients with syndromic vs. non-syndromic symptoms revealed a significant overlap of frequent causes of monogenic epilepsies, including SCN1A, CACNA1A, and SETD1B, confirming the heterogeneity of the associated conditions. In patients with seizures-regardless of the detailed phenotype-a monogenic cause can be frequently identified, often implying a possible change in therapeutic action (36.7% (37/109) of PV/VUS variants); this justifies early and broad application of genetic testing. Our data suggest that the diagnostic yield is highest in exome or trio-exome-based testing, resulting in a molecular diagnosis within 3 weeks, with profound implications for therapeutic strategies and for counseling families and patients regarding prognosis and recurrence risk.

To categorise the variants of uncertain significance found with prenatal chromosomal microarray and determine the proportion of such variants that are associated with a well-known phenotype in order to establish how often they remain truly of uncertain significance. Retrospective cohort study. The University of California, San Francisco. All patients with a variant of uncertain significance on prenatal microarray between 2014 and 2018. Each variant was classified as a copy number variant that (a) contains Online Mendelian Inheritance in Man (OMIM)-annotated disease-causing genes ('OMIM morbid genes'); (b) confers autosomal recessive carrier status; (c) is associated with incomplete penetrance; (d) is >1Mb in size without OMIM morbid genes; (e) demonstrates mosaicism; or (f) contains significant regions of homozygosity. For each variant of uncertain significance, we examined the existing literature to determine whether the predicted phenotype(s) was known. Prevalence and classification of variants and how much information is available regarding the likelihood of an affected phenotype. Of 970 prenatal microarrays, 55 (5.8%) had at least one variant of uncertain significance. The most common were copy number variants containing OMIM morbid genes (36.8%). In all, 48 (84.2%) were associated with a known phenotype; 55 (96.5%) had data available regarding the likelihood of an affected phenotype. The prevalence of variants of uncertain significance with prenatal microarray was 5.8%. In the large majority of cases, data were available regarding the predicted phenotype. Variants of uncertain significance occur in 5.8% of prenatal microarrays. In the overwhelming majority of cases, outcome information is available.

Anemia is less prominent in patients with polycystic kidney disease (PKD). Such iron indices as ferritin and transferrin saturation (TSAT) values are used to guide management of anemia in individuals on maintenance hemodialysis (MHD). Optimal levels of correction of anemia and optimal levels of TSAT and ferritin are unclear in chronic kidney disease patients and have not been studied specifically in PKD. We studied 2969 MHD patients with and 128 054 patients without PKD from 580 outpatient hemodialysis facilities between July 2001 and June 2006. Using baseline, time-dependent and time-averaged values with unadjusted and multivariable adjusted analysis models, the survival predictabilities of TSAT and ferritin were studied. PKD patients were 58 ± 13 years old and included 46% women, whereas non-PKD patients were 62 ± 15 years old and 45% women. In both PKD and non-PKD patients, a time-averaged TSAT between 30 and 40% was associated with the lowest mortality. Time-averaged ferritin between 100 and <800 ng/mL was associated with the lowest mortality in PKD patients, although this range was 500 to <800 ng/mL in non-PKD patients. In MHD patients with and without PKD, there was a U-shaped relationship between the average TSAT and mortality, and a TSAT of 30-40% was associated with the best survival. However, an average ferritin of 100-800 ng/mL was associated with the best survival in PKD patients, whereas that of non-PKD patients was 500-800 ng/mL. Further studies in PKD and non-PKD patients are necessary to determine whether or not therapeutic attempts to keep TSAT and ferritin levels in these ranges will improve survival.

Background and Aims Recent advances in genetic molecular techniques have allowed the expansion of knowledge in glomerular diseases of genetic cause, including the identification of genes involved in focal and segmental glomerular sclerosis (FSGS). The prevalence of adult-onset genetic FSGS varies widely depending on the population studied. In central Europe, NPHS2 and COL4A3, COL4A4 e COL4A5 genes are postulated to be the most frequent genes implicated in genetic causes of adult FSGS. This study aims to characterize patients submitted to genetic study of glomerular diseases in the Nephrogenetics Clinic of our centre. Method We conducted a single-centre retrospective analysis of the patients submitted to genetic study of glomerular diseases in the Nephrogenetics Clinic of our centre from 2016 to 2022. Adult patients with a glomerular disease phenotype suggestive of a genetic cause were studied, using a predetermined phenotype-targeted panel of genes, through massive parallel sequencing. The number of genes included in this panel has increased (from 21 genes in 2016 to 49 genes since 2018); given this change, patients with a negative result on the first approach repeated screening with the broader panel. Additionally, patients presenting with advanced chronic kidney disease (CKD) without an identifiable phenotype, studied with a larger panel for CKD causing genes, are reported. In patients with a negative result but highly suggestive presentation, whole exome sequencing (WES) was considered, after multidisciplinary discussion with a Geneticist's evaluation. Patients with variants of unknown significance (VUS) were referred to a Genetics’ consultation for genetic counselling and segregation studies. Results Of the 80 patients studied (comprising 74 families), 52.5% were female (n=42) and 79% (n=63) of Caucasian ascent. Mean age was 45.4 ± 16.0 years. Nine patients were studied with the larger gene panel for CKD. 85% (n=68) had CKD (all stages) at presentation, with proteinuria (ranging from sub-nephrotic to nephrotic range) and 15% had asymptomatic urinary changes. 50% (n=40) of patients had positive family history, and 31% (n=25) had a syndromic presentation and/or extra renal manifestations. 27.5% (n=22) had a renal biopsy, and the most prevalent result was FSGS (11%; n=9). Genetic variants were identified in 70% (n=56) of the patients; but pathogenicity is not fully established in all: genotype-phenotype correlations, including inheritance pattern and histological correlation, and segregation studies (when indicated and possible) are ongoing. In 5 patients results are pending. Pathogenic / likely pathogenic variants were identified in at least 47.5% (n=38) patients. The most frequently implicated genes were: COL4A3, COL4A4 e COL4A5 (n=21), high risk APOL1 (n=8); NPSH2 (n=5), IFN2 (n=6, 3 pathogenic, 1 variant of unknown significance (VUS), 2 under segregation studies) and MYH9 (n=3). COL4A3, COL4A4 e COL4A5 mutations occur with Alport syndrome, but also with histologically documented FSGS, sub-nephrotic and nephrotic proteinuria, nephrotic syndrome and asymptomatic urinary changes. In our cohort, NPHS2 p.R229Q was identified in 5 patients (6%), but only with pathogenic significance in 3 patients, and APOL1 high risk haplotype was co-identified with COL4 variants in 3 patients. Conclusion The genetic study of a cohort of patients suspected of genetic FSGS allowed the identification of genetic variants in the genes of interest in a high percentage of cases. The most frequently implicated genes were COL4A3, COL4A4 e COL4A5, NPHS2, INF2 and APOL1 high risk haplotype. The high percentage of gene variants identified in our cohort is probably due to the selection of a population with a high likelihood of genetic FSGS. Further studies will clarify the causal and/or modifier effect of some genes, namely COL4A3, COL4A4 e COL4A5. The future use of WES in cases of high likelihood of genetic cause will probably allow the identification on novel candidate genes and increase the clinical benefits of a genetic diagnosis of FSGS.

1525 Background: Genetic testing is a powerful tool for stratifying cancer risk. Multiplex gene panel (MGP) testing allows simultaneous analysis of multiple high- and moderate- penetrance genes. However, the diagnostic yield and clinical utility of panels remain to be further delineated. Methods: A report of a fully accrued trial (N = 2000) of patients undergoing cancer-risk assessment. Patients were enrolled in a multicenter prospective cohort study where diagnostic yield and off-target mutation detection was evaluated of a 25 gene MGP comprised of APC, ATM, BARD1, BMPR1A, BRCA1, BRCA2, BRIP1, CDH1, CDK4, CDKN2A, CHEK2, EPCAM, MLH1, MSH2, MSH6, MUTYH, NBN, PALB2, PMS2, PTEN, RAD51C, RAD51D, SMAD4, STK11, TP53. Patients were enrolled if they met standard testing guidelines or were predicted to have a ≥2.5% mutation probability by validated models. Differential diagnoses (DDx) were generated after expert clinical genetics assessment, formulating up to 8 inherited cancer syndromes ranked by estimated likelihood. Results: 1998/2000 patients had reported MGP test results. Women constituted 81% of the sample, and 40% were Hispanic; 241 tested positive for at least 1 pathogenic mutation (12.1%) and 689 (34.5%) patients carried at least 1 variant of uncertain significance. The most frequently identified mutations were in BRCA1 (17%, n = 41), BRCA2 (15%, n = 36), APC (8%, n = 19), CHEK2 (7%, n = 17), ATM (7%, n = 16). 39 patients (16%) had at least 1 pathogenic mutation in a mismatch repair (MMR) gene ( MLH1, n = 10; MSH2, n = 10; MSH6, n = 8; PMS2, n = 11). 43 individuals (18%) had MUTYH mutations – 41 were monoallelic. Among 19 patients who had mutations in APC – 16 were APC I1307K. Only 65% (n = 159) of PV results were included in the DDx, with 35% (n = 86) of mutations not clinically suspected. Conclusions: In a diverse cohort, multiplex panel use increased genetic testing yield substantially: 35% carried pathogenic mutations in unsuspected genes, suggesting a significant contribution of expanded multiplex testing to clinical cancer risk assessment. The identification of off-target mutations broadens our understanding of cancer risk and genotype-phenotype correlations. Follow-up is ongoing to assess the clinical utility of multiplex gene panel testing. Clinical trial information: NCT02324062.

ColoSeq Provides Comprehensive Lynch and Polyposis Syndrome Mutational Analysis Using Massively Parallel Sequencing

Background: The recent introduction of clinical Next Generation Sequencing (NGS) technologies has transformed the ability of health care providers to provide personalized hereditary breast cancer risk assessments to patients and their family members. However, along with the plethora of data derived from NGS technologies come challenges regarding how to interpret this data in a clinically meaning way to guide medical management decisions. Methods: A retrospective analysis was performed on a population of 242 patients with a personal or family history of breast and/or ovarian cancer and completed NGS genetic testing between March 2012 and May 2014 at Ambry Genetics. Data points included age, gender, primary diagnosis, type of NGS genetic test and result. Patients with prior genetic testing were not excluded from the analysis. Results: Of the 242 patients who completed NGS genetic testing 199 (82%) had a personal history of cancer and 43 (18%) had a family history of cancer. Ten (5%) clinically significant deleterious mutations were found in the affected population; 3 MUTYH mutations were consider not clinically significant and excluded from the analysis. Four (40%) were CHEK2 mutations, 2(20%) BRCA1 mutations, 1(10%) NBN mutation, 1(10%) ATM mutation, 1(10%) MSH6 mutation and 1(10%) PTEN mutation. One patient with a history of ovarian cancer had two deleterious mutations in the BRCA1 and NBN genes, and three affected patients had a deleterious mutation in addition to a variant of uncertain significance (VUS); a patient with synchronous breast and ovarian cancers had a MSH6 mutation and a BRCA2 VUS, a patient with breast cancer had a CHEK2 mutation and a CHEK2 VUS, and a patient with breast cancer had a CHEK2 mutation and a MSH6 VUS. A total of 37 (19%) VUS were found in the affected population, including one patient with a history of breast cancer and a VUS in both ATM and MRE11A. A single (2%) clinically significant BRCA1 deleterious mutation and 6(14%) VUS were detected in the unaffected population. Conclusions: NGS technologies allow for health care providers to complete more comprehensive hereditary breast cancer risk assessments for patients and their families. However, the high VUS rate (14-19%) and the possibility for multiple mutations and/or variants in a single patient create unique challenges when interpreting NGS genetic test results. Furthermore, the paucity of prospective studies and consensus guidelines limits the ability of the health care provider to interpret NGS genetic test results in a clinically meaningful way to guide patient management. This is highlighted by the case example above regarding the patient with synchronous breast and ovarian cancers who was found to have a MSH6 mutation and a BRCA2 VUS. Given that the patient does not meet Amsterdam criteria, the MSH6 mutations would have been missed had it not been for the NGS technology utilized for this patient. However, challenges still exist about how to interpret this data for both the patient and her family in a clinically meaningful way given that the family does not look like a classic Lynch Syndrome family. Citation Format: Barbara Hamlington, Scot Sedlacek, Lucy Langer, Brittney Goetsch, Katie Lemas, Sami Diab. Utilizing next generation sequencing technologies for hereditary breast cancer risk assessments in a private oncology practice [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P4-12-08.

Recent advances in next-generation sequencing (NGS) technology have enabled multigene testing and changed the diagnostic approach to hereditary gastrointestinal cancer/polyposis syndromes. The aim of this study was to analyze different cancer predisposition genes in hereditary/sporadic gastrointestinal cancer/polyposis. Cancer predisposition genes were analyzed with an Illumina MiSeq NGS system in 80 patients with gastrointestinal cancer/polyposis who were examined between the years 2016 and 2019. Deletion/duplication analysis of MLH1, MSH2, and EPCAM genes was performed by using the multiplex ligation-dependent probe amplification method. Germline testing of hereditary cancer-related genes was performed in 80 patients with gastrointestinal cancer/polyposis. A total of 30 variants in 30 cases (37.5%) were assessed as pathogenic/likely pathogenic. A total of 19 heterozygous variants were assessed as variants of uncertain clinical significance in 17 cases (21.25%) and 18 (22.5%) novel variations (9 pathogenic/likely pathogenic, 9 variants of uncertain significance) were determined. In 4 (5%) cases, multiplex ligation-dependent probe amplification detected deletions in MLH1, MSH2, and EPCAM genes. The accumulation of analyses with multigene testing will increase the available data for cancer predisposition genes in hereditary gastrointestinal cancer/polyposis. Educational campaigns for prevention, efficient screening programs, and more personalized care based on the profile of individual patients are necessary.

The content of the 13th Mutation Detection meeting (Leiden, April 2015) is summarized in this report. Topics discussed at the meeting included current challenges of clinical NGS, advances in bioinformatics, data quality control, single cell analysis and RNA sequencing, among others. Social, ethical and regulatory challenges of genomic data handling and data sharing were the focus of an expert panel debate. The 14th International Symposium on Variants in the Genome will take place in Santiago de Compostela, June 5-8, 2017. http://isv.variome.org.

Introduction: Previous studies have reported conflicting results on the outcomes of double-balloon enteroscopy (DBE) and single-balloon enteroscopy (SBE). We aimed to compare efficacy and safety of DBE to SBE via retrograde approach. Methods: We performed a retrospective analysis of all patients who underwent retrograde DBE or SBE at a large, tertiary referral center from 2008 to 2018. Data was collected on demographics, baseline comorbidities, antiplatelet and anti-coagulation use. Outcomes assessed included technical success, diagnostic yield, therapeutics, depth of insertion and procedural duration. The analysis was done using SPSS software. Results: A total of 523 (403 DBE, 120 SBE) patients underwent retrograde enteroscopy during the study period. The mean age was 59.4 ± 17.24 and 59.57 ± 16.94 in DBE and SBE group, respectively. There was no difference in gender, comorbidities, smoking history, clopidogrel, anti-coagulation use, platelet count, and laboratory parameters between both groups. Aspirin use was significantly higher in DBE group (40.8% vs. 29.9%, P = 0.03) (Table 1). The indication for enteroscopy was obscure gastrointestinal bleeding (OGIB) in 66.5% and 55.8% of DBE and SBE procedures, respectively. There was no difference in technical success (91.0% vs. 92.5%, P = 0.85), diagnostic yield (40.9% vs. 40.8%, P = 0.95) and therapeutics (17.1% vs. 19.1%, P = 0.61) between DBE and SBE. Compared to SBE, DBE had significantly shorter mean procedure time (26.5 ± 34.5 min vs. 34.8 ± 29.4 min, P = 0.01) but higher maximal depth of insertion from ileo-cecal valve (108.1 ± 84.1 cm vs. 73.3 ± 63.4 cm, P = 0.001). In addition, proximal ileum was reached in 22.6% of DBE procedure as compared to 6% in SBE (P < 0.001). On subgroup analysis based on OGIB indication, DBE again had significantly higher depth of insertion (113.1 ± 87.07 cm vs. 79.9 ± 66.5 cm, P = 0.02) and rates of proximal ileum reach (23.7% vs. 7.1%, P = 0.006) as compared to SBE but there was no statistically significant difference in diagnostic yield (34.5% vs. 26.9%, P = 0.23) and therapeutics (20.3% vs. 14.9%, P = 0.31). Safety events were rare and similar in both groups (Table 2). Conclusion: Retrograde DBE is associated with significantly higher depth of insertion and shorter procedural duration but similar diagnostic yield and technical success as compared to.Figure:: Baseline and Demographics factors for both groupsTable 2.: Outcomes comparing DBE and SBE

The aim of this study was to evaluate the corneal biomechanical features in polycystic kidney disease (PKD) patients and compare them with the healthy individuals. Totally 81 patients with a mean age of 48.46±14.51years and 60 control cases with a mean age of 44.68±12.69years were included in the study. All of the subjects underwent a complete ophthalmological examination, including visual acuity testing, biomicroscopic anterior and posterior segment examinations. Corneal hysteresis (CH), corneal resistance factor (CRF), Goldmann-correlated intraocular pressure (IOPg) and corneal-compensated intraocular pressure (IOPcc) were evaluated with the ocular response analyzer, and the central corneal thickness was evaluated with Sirius® corneal topography. PKD patients had significantly increased CH values, without any alterations in IOP or CCT values, compared with the control cases (p:0.001). Among PKD patients, 23 were having liver cysts accompanying renal cysts. There was not any statistically significant difference between PKD patients with or without liver cysts regarding biomechanical properties of the cornea. However, both patient groups had statistically significantly increased CH values compared with the control cases. Patients with PKD present with higher CH values than age-matched controls. Larger studies are warranted to elucidate the alterations in corneal biomechanical properties and their clinical relevance in PKD patients.

Introduction: Polycystic kidney disease (PKD) is a genetic disorder that leads to the development of renal cysts and progressive chronic kidney disease. The primary genetic variants leading to PKD are PKD1 and PKD2, which encode for the protein polycystin-1. This protein is a building block for the architecture and function of the renal tubule. Disruption in the code affects the integrity of the renal parenchyma, leading to cyst formation and a decline in renal function over time. Case Description: A 41-year-old female presented for elevated serum creatinine and a significant family history of PKD in her father and son. Her father underwent nephrectomy of his native polycystic kidneys, and her son was diagnosed with PKD after a workup of microscopic hematuria. During her workup, she underwent a renal ultrasound (Figures 1a and 1b), which revealed PKD Mayo Clinic classification 1b with additional hepatic cysts. Laboratory testing showed declining renal function with an estimated glomerular filtration rate of 48 mL/min/1.73 m2. Genetic testing was performed that was absent any known pathogenic mutation. However, a variant of unknown significance was detected with a single heterozygous non-truncating variant in PKD1 c.11214C>G (p.Asn3738Lys) predicted to result in a single amino acid substitution of Asn to Lys at codon 3738 in exon 39. 5. Discussion with genetic testing laboratory director found that it would still take time to reclassify this variant as more data becomes available with a recommendation the patient's father and/or son also undergo genetic testing to better understand the clinical significance of this variant. Discussion: PKD varies in disease severity and progression due to the complex relationship between genetic variability and epigenetic factors. With a size of over 4000 amino acids, it has been observed that small changes have profound effects on the polycystin-1 function. This case highlights the identification of novel genetic variants with potential pathological effects in PKD and the importance of enhancing our understanding of the disease at a molecular level. Further studies would be necessary to evaluate the significance of this variant to the phenotypic development of PKD.