Comprehensive Genetic Analysis Reveals Complexity of Monogenic Urinary Stone Disease

Introduction

Because of phenotypic overlap between monogenic urinary stone diseases (USD), gene-specific analyses can result in missed diagnoses. We used targeted next generation sequencing (tNGS), including known and candidate monogenic USD genes, to analyze suspected primary hyperoxaluria (PH) or Dent disease (DD) patients genetically unresolved (negative; N) after Sanger analysis of the known genes. Cohorts consisted of 285 PH (PHN) and 59 DD (DDN) families.

Methods

Variants were assessed using disease-specific and population databases plus variant assessment tools and categorized using the American College of Medical Genetics (ACMG) guidelines. Prior Sanger analysis identified 47 novel PH or DD gene pathogenic variants.

Results

Screening by tNGS revealed pathogenic variants in 14 known monogenic USD genes, accounting for 45 families (13.1%), 27 biallelic and 18 monoallelic, including 1 family with a copy number variant (CNV). Recurrent genes included the following: SLC34A3 (n = 13), CLDN16 (n = 8), CYP24A1 (n = 4), SLC34A1 (n = 3), SLC4A1 (n = 3), APRT (n = 2), CLDN19 (n = 2), HNF4A1 (n = 2), and KCNJ1 (n = 2), whereas ATP6V1B1, CASR, and SLC12A1 and missed CNVs in the PH genes AGXT and GRHPR accounted for 1 pedigree each. Of the 48 defined pathogenic variants, 27.1% were truncating and 39.6% were novel. Most patients were diagnosed before 18 years of age (76.1%), and 70.3% of biallelic patients were homozygous, mainly from consanguineous families.

Conclusion

Overall, in patients suspected of DD or PH, 23.9% and 7.3% of cases, respectively, were caused by pathogenic variants in other genes. This study shows the value of a tNGS screening approach to increase the diagnosis of monogenic USD, which can optimize therapies and facilitate enrollment in clinical trials.

Genome-wide Association Study of 24-Hour Urinary Excretion of Calcium, Magnesium, and Uric Acid

Objectives

The urinary excretion of organic and inorganic substances and their concentrations have attracted extensive attention for their role in the pathogenesis of urinary stone disease. The urinary excretion of specific factors associates with sex and age and seems to have a hereditary component, but the precise genomic determinants remain ill-defined.

Methods

Genome-wide association studies previously conducted in 3 cohorts (Genetic Epidemiology Network of Arteriopathy study, January 1, 2006, through December 31, 2012; the combined Nurses’ Health Study (NHS), NHS II, and Health Professionals Follow-up Study, January 1, 1994, through December 31, 2003; and the Prevention of Renal and Vascular End-stage Disease study, January 1, 1997, through December 31, 1998) were combined into meta-analyses to evaluate genetic associations with available urinary phenotypes relevant to stone pathogenesis (calcium, magnesium, and uric acid excretion; total urine volume).

Results

One region on chromosome 9q21.13 showed strong evidence of an association with urinary magnesium excretion. The strongest signal in this region was near TRPM6, whose protein product mediates magnesium transport in the colon and kidney, and C9orf40, C9orf41, NMRK1, and OSTF1 (rs1176815; P=1.70×10^–14, with each copy of the A allele corresponding to a daily 5.29-mg decrease in magnesium excretion). The single nucleotide polymorphism (SNP) that achieved genome-wide significance for calcium excretion (rs17216707 on chromosome 20; P=1.12×10^–8) was previously associated with fibroblast growth factor 23 levels, which regulate phosphorus and vitamin D metabolism. Urine volume and uric acid excretion did not have any genome-wide significant SNPs.

Conclusion

Common variants near genes important for magnesium metabolism and bone health associate with urinary magnesium and calcium excretion.

P593Oxygen sensitive cardiac magnetic resonance in demonstrating myocardial ischaemia of the right ventricle in patients with pulmonary artery hypertension

Background

Progressive right ventricular (RV) dysfunction is a natural progression of pulmonary arterial hypertension (PAH) which is associated with adverse clinical outcomes. The main contributor to progressive RV dysfunction is RV ischemia. Oxygen-sensitive (OS) cardiovascular magnetic resonance (CMR) has been used to determine the in-vivo myocardial oxygenation of the left ventricle (LV).

Purpose

The aim of the present study was to (1) Determine the feasibility of RV targeted rest/stress OS-CMR imaging in PAH patients and normal volunteers; (2) To define the presence and extent of RV myocardial ischaemia in patients with known PAH.

Methods

We prospectively recruited 20 patients with right heart catheter proven PAH and 9 normal (NC), age matched controls with no heart disease. The CMR examination involved standard functional imaging and OS-CMR imaging. OS-CMR images were acquired using a T2* sequence at rest and adenosine-induced stress vasodilatation. The RV was divided into 3 segments - RV anterior, RV free-wall and RV inferior. An OS-CMR signal intensity (SI) index (stress/rest signal intensity) was acquired at RV anterior, RV free-wall and RV inferior segments.

Results

All the PAH patients tolerated and completed the adenosine induced stress OS-CMR without any complications or adverse effects. In NC, reliable OS signal intensity changes was only obtained from the RV inferior segment. As RV dysfunction in PAH is a global process, hence this segment was used in both patients and NC for further comparison. RV OS-CMR signal intensity change between rest and stress in the normal volunteers was 17±4% (mean ± SD). 9 out of twenty (45%) of the PAH patients had a mean BOLD signal intensity change of less than 9% (or 2SD different from the mean values in normal volunteers). Overall, RV OS SI index between the PAH patients and controls was 11±9% vs 17±5% (p-value = 0.045) in RV inferior segment.

Conclusion

Pharmacological induced OS-CMR is a feasible and safe technique to identify and study myocardial oxygenation in the RV of PAH patients.

Effect of Lung Transplantation on Health-Related Quality of Life in the Era of the Lung Allocation Score: A U.S. Prospective Cohort Study

Under the U.S. Lung Allocation Score (LAS) system, older and sicker patients are prioritized for lung transplantation (LT). The impact of these changes on health-related quality of life (HRQL) after transplant has not been determined. In a single-center prospective cohort study from 2010 to 2016, we assessed HRQL before and repeatedly after LT for up to 3 years using the SF12-Physical and Mental Health, the respiratory-specific Airway Questionnaire 20-Revised, and the Euroqol 5D/Visual Analog Scale utility measures by multivariate linear mixed models jointly modeled with death. We also tested changes in LT-Valued Life Activities disability, BMI, allograft function, and 6-min walk test exercise capacity as predictors of HRQL change. Among 211 initial participants (92% of those eligible), LT improved HRQL by all 5 measures (p < 0.05) and all but SF12-Mental Health improved by threefold or greater than the minimally clinically important difference. Compared to younger participants, those aged ≥65 improved less in SF12-Physical and Mental Health (p < 0.01). Improvements in disability accounted for much of the HRQL improvement. In the LAS era, LT affords meaningful and durable HRQL improvements, mediated by amelioration of disability. Identifying factors limiting HRQL improvement in selected subgroups, especially those aged ≥65, are needed to maximize the net benefits of LT.

Early plasma soluble receptor for advanced glycation end-product levels are associated with bronchiolitis obliterans syndrome

Early epithelial injury after lung transplantation may contribute to development of bronchiolitis obliterans syndrome (BOS). We evaluated the relationship between early postoperative soluble receptor for advanced glycation end-product (sRAGE) levels, a marker of type I alveolar cell injury and BOS. We performed a cohort study of 106 lung transplant recipients between 2002 and 2006 at the University of Pennsylvania with follow-up through 2010. Plasma sRAGE was measured 6 and 24 h after transplantation. Cox proportional hazards models were used to evaluate the association between sRAGE and time to BOS, defined according to ISHLT guidelines. Sixty (57%) subjects developed BOS. The average time to BOS was 3.4 years. sRAGE levels measured at 6 h (HR per SD of sRAGE: 1.69, 95% CI: 1.11, 2.57, p = 0.02) and 24 h (HR per SD of sRAGE: 1.74, 95% CI: 1.14, 2.65, p = 0.01) were associated with an increased hazard of BOS. Multivariable Cox regression indicated this relationship was independent of potential confounders. Elevated plasma sRAGE levels measured in the immediate postoperative period are associated with the development of BOS. Early epithelial injury after transplantation may contribute to the development of fibrosis in BOS.

Classification of probe-based confocal laser endomicroscopy findings in pancreaticobiliary strictures

BACKGROUND AND STUDY AIMS

The accurate diagnosis of indeterminate pancreaticobiliary strictures presents a clinical dilemma. Probe-based confocal laser endomicroscopy (pCLE) offers real-time in vivo microscopic tissue examination that may increase sensitivity for the detection of malignancy. the objective of this study was to develop and validate a standard descriptive classification of pcle in the pancreaticobiliary system.

PATIENTS AND METHODS

A total of 102 patients undergoing endoscopic retrograde cholangiopancreatography (ERCP) with pCLE to assess indeterminate pancreaticobiliary strictures were enrolled in a multicenter registry; 89 of these patients were evaluable. Information and data on the following were collected prospectively: clinical, ERCP, tissue sampling, pCLE, and follow-up. A uniform classification of pCLE findings ("Miami Classification") was developed, consisting of a set of image interpretation criteria. Thereafter, these criteria were tested through blinded consensus review of 112 randomized pCLE videos from 47 patients, and inter-observer variability was assessed in 42 patients .

RESULTS

A consensus definition of the specific criteria of biliary and pancreatic pCLE findings for indeterminate strictures was developed. Single-image interpretation criteria did not have a high enough sensitivity for predicting malignancy. However, combining two or more criteria significantly increased the sensitivity and predictive values. The characteristics most suggestive of malignancy included the following: thick white bands (>20 µm), or thick dark bands (>40 µm), or dark clumps or epithelial structures. These provided sensitivity, specificity, positive predictive value, and negative predictive value of 97%, 33%, 80%, and 80% compared with 48%, 100%, 100%, and 41% for standard tissue sampling methods. Inter-observer variability was moderate for most criteria.

CONCLUSION

The Miami Classification enables a structured, uniform, and reproducible description of pancreaticobiliary pCLE. Combining individual characteristics improves the sensitivity for the detection of malignancy.

Usefulness of colonoscopy with biopsy in the evaluation of patients with chronic diarrhea

OBJECTIVE

Patients referred for chronic diarrhea frequently undergo endoscopic evaluation. There are limited data on the role for colonoscopy with biopsy and ileoscopy for patients with chronic diarrhea.

METHODS

We reviewed the charts of 228 patients with chronic diarrhea evaluated by colonoscopy between November 1995 and March 1998. Chronic diarrhea was defined as loose, frequent bowel movements for a minimum of 4 wk. Patients were excluded if biopsies were not performed in normal colons, if they had undergone previous bowel surgery, a history of inflammatory bowel disease, HIV, or an inadequate colonoscopy.

RESULTS

One hundred sixty-eight patients were included in the analysis, of whom 142 (85%) had ileoscopy. Colonoscopy and biopsy yielded a specific histological diagnosis in 52 (31%) patients. These included Crohn's disease (9), ulcerative colitis (7), lymphocytic colitis (10), collagenous colitis (3), ischemic colitis (3), infectious colitis (6), and miscellaneous diseases (14). Ileoscopy yielded significant findings in 3% of patients (four with Crohn's disease and one with infection).

CONCLUSIONS

Colonoscopy and biopsy is useful in the investigation of patients with chronic diarrhea yielding a histological diagnosis in 31% of patients without a previous diagnosis. Ileoscopy complemented colonoscopy findings in a minority of patients with chronic diarrhea and was essential for a diagnosis in only two patients.

Members of the Sp transcription factor family regulate rat calmodulin gene expression

We have previously demonstrated that insulin positively regulates transcription of the rat calmodulin (CaM) I gene and that both basal and insulin stimulation of this gene are critically dependent on Sp1. Furthermore, a 392 bp CaM promoter was stimulated by insulin equal to the full promoter but lost activity with deletion of any of the three Sp1 sites (Solomon SS, Palazzolo MR, Takahashi T, Raghow R. Endocrinology 1997;138:5052-5054). Herein we document that Sp1 preferentially binds to the upstream sites Sp1(2) and Sp1(3) but not Sp1(1). Furthermore, gel-mobility super-shift assays demonstrate that both Sp1 and Sp3 protein are found in these complexes. When pPac-Spl, pPac-Sp3, pPac-USp3, and pPac-Sp4 were cotransfected with rCaM 1-392 promoter into Drosophila SL2 cells and challenged with 10,000 microU/mL insulin, we discovered that (1) Sp1 enhanced both basal and insulin-stimulated CaM I gene expression; (2) USp3, a "long" form of the Sp3 molecule, had a stimulatory effect on CaM I gene expression; (3) Sp1 or USp3 is involved in mediating insulin-stimulation of the CaM I gene in SL2 cells; and (4) Sp3, a "short" form of the Sp3 molecule, and Sp4 inhibited Spl-stimulated and insulin-stimulated Sp1-mediated CaM I gene expression. Together these data corroborate and extend our previous observations on Sp1 and elucidate that other members of the Sp family of transcription factors may also be involved in regulating the activity of the CaM promoter.

Endoscopic retrograde cholangiopancreatography in the diagnosis and management of pancreatic diseases

Endoscopic retrograde cholangiopancreatography (ERCP) has been used for diagnosis and treatment of pancreatic diseases for over 20 years. ERCP has been most intensely investigated for acute biliary pancreatitis. Randomized trials have proven that its use will decrease morbidity and have suggested a decrease in mortality for patients with severe gallstone pancreatitis. ERCP is also valuable in detecting and treating main pancreatic duct leaks with transpapillary stenting. Symptomatic pseudocysts, which may be seen in either acute or chronic pancreatitis, can be drained via the papilla or through creation of a cystogastrostomy or cystoduodenostomy with a needle-knife sphincterotome. Endoscopic treatment of patients with recurrent acute pancreatitis presumed due to pancreas divisum and sphincter of Oddi dysfunction remains controversial. Dominant pancreatic strictures or calculi in the setting of chronic pancreatitis may be treated with stenting and removal of calculi to improve abdominal pain. Finally, diagnosis of pancreatic cancer by brush cytology and palliative management of biliary obstruction with various plastic and expandable metal sents have simplified management of this difficult problem.

Thin layer chromatographic identification of some sympathomimetic amines

Thin layer chromatographic behavior of some sympathomimetic amines in the presence of acids in neutral and organic solvent systems is reported. The sympathomimetic amines were dissolved in 0.1N HCl or ethanol and treated with bromocresol green or p-nitrobenzoyl chloride reagents on fiber sheets or precoated glass plates. Two-, 3-, and 4-, component solvent systems were tested. Benzene-ethyl acetate gave 2 spots for each amine standard; the more polar spots were satisfactorily separated. Amines in pharmaccuticals were not separated by any solvent system tested.