Outcomes of patient self-referral for the diagnosis of several rare inherited kidney diseases

Autosomal dominant ApoA4 mutations present as tubulointerstitial kidney disease with medullary amyloidosis

Sporadic cases of apolipoprotein A-IV medullary amyloidosis have been reported. Here we describe five families found to have autosomal dominant medullary amyloidosis due to two different pathogenic APOA4 variants. A large family with autosomal dominant chronic kidney disease (CKD) and bland urinary sediment underwent whole genome sequencing with identification of a chr11:116692578 G>C (hg19) variant encoding the missense mutation p.L66V of the ApoA4 protein. We identified two other distantly related families from our registry with the same variant and two other distantly related families with a chr11:116693454 C>T (hg19) variant encoding the missense mutation p.D33N. Both mutations are unique to affected families, evolutionarily conserved and predicted to expand the amyloidogenic hotspot in the ApoA4 structure. Clinically affected individuals suffered from CKD with a bland urinary sediment and a mean age for kidney failure of 64.5 years. Genotyping identified 48 genetically affected individuals; 44 individuals had an estimated glomerular filtration rate (eGFR) under 60 ml/min/1.73 m2, including all 25 individuals with kidney failure. Significantly, 11 of 14 genetically unaffected individuals had an eGFR over 60 ml/min/1.73 m2. Fifteen genetically affected individuals presented with higher plasma ApoA4 concentrations. Kidney pathologic specimens from four individuals revealed amyloid deposits limited to the medulla, with the mutated ApoA4 identified by mass-spectrometry as the predominant amyloid constituent in all three available biopsies. Thus, ApoA4 mutations can cause autosomal dominant medullary amyloidosis, with marked amyloid deposition limited to the kidney medulla and presenting with autosomal dominant CKD with a bland urinary sediment. Diagnosis relies on a careful family history, APOA4 sequencing and pathologic studies.

Maternal health and pregnancy outcomes in autosomal dominant tubulointerstitial kidney disease

Introduction

Autosomal dominant tubulointerstitial kidney disease (ADTKD) is an increasingly recognized cause of chronic kidney disease. ADTKD pregnancy outcomes have not previously been described.

Methods

A cross-sectional survey was sent to women from ADTKD families.

Results

Information was obtained from 85 afffected women (164 term pregnancies) and 23 controls (50 pregnancies). Only 16.5% of genetically affected women knew they had ADTKD during pregnancy. Eighteen percent of ADTKD mothers had hypertension during pregnancy versus 12% in controls (p  =  0.54) and >40% in comparative studies of chronic kidney disease in pregnancy. Eleven percent of births of ADTKD mothers were <37 weeks versus 0 in controls (p < 0.0001). Cesarean section occurred in 19% of pregnancies in affected women versus 38% of unaffected individuals (p  =  0.06). Only 12% of babies required a neonatal intensive care unit stay.

Conclusions

ADTKD pregnancies had lower rates of hypertension during pregnancy versus other forms of chronic kidney disease, which may have contributed to good maternal and fetal outcomes.

Getting Your Foot in the Door: Access to Surgical Care for Thyroid Disease

INTRODUCTION

Access to specialty care can be challenging for patients, often involving multiple evaluations, laboratory tests, and referrals. To better understand the different pathways to specialty care, we examined the outcomes of patients evaluated for surgical thyroid disease at a single tertiary referral clinic.

METHODS

We reviewed 691 patients seen in the endocrine surgery clinic for thyroid disease (2018-2021). Patient demographics, referral source, referral reason, and reason for not receiving an operation were collected. The number of days from referral to initial clinic visit and from initial clinic visit to an operation were also collected. The Chi-square test, the independent t-test, the Kruskal-Wallis test, the Dunn-Bonferroni post hoc test, and multiple logistic regression tests were performed using SPSS.

RESULTS

The top reasons for referral were thyroid nodules (54.4%), hyperthyroidism (26.5%), and multinodular goiter (10.3%). Specialty clinic referrals came from endocrinologists (56.0%), self-referrals (15.5%), and primary care physicians (PCP; 14.4%). Self-referred patients had a shorter waiting time for an appointment than those referred by endocrinologists and PCPs. [median (IQR) (days) 12 (6-17) versus 16 (9-24) versus 16 (9-25), P < 0.001]. Overall, 450 (72.7%) patients underwent thyroid surgery. For those who underwent thyroidectomy, self-referred patients had a shorter time between initial clinic visit and the operation compared to those referred by endocrinologists and PCPs [median (IQR) (days) 2 (1-19) versus 19 (8-33) versus 16 (1-48), P < 0.001]. Patients referred for hyperthyroidism (odds ratio [OR] = 2.2, 95% confidence interval [CI] 1.3-10.5, P = 0.012 were more likely to undergo an operation than those referred for other reasons.

CONCLUSIONS

Access to specialty care for thyroid disease is facilitated and optimized when self-referrals are permitted. Reducing or eliminating the requirement for a provider referral may improve patients' access.

Autosomal dominant tubulointerstitial kidney disease: A review

The clinical characteristics of autosomal dominant tubulointerstitial kidney disease (ADTKD) include bland urinary sediment, slowly progressive chronic kidney disease (CKD) with many patients reaching end stage renal disease (ESRD) between age 20 and 70 years, and autosomal dominant inheritance. Due to advances in genetic diagnosis, ADTKD is becoming increasingly recognized as a cause of CKD. Pathogenic variants in UMOD, MUC1, and REN are the most common causes of ADTKD. ADTKD-UMOD is also associated with hyperuricemia and gout. ADTKD-REN often presents in childhood with mild hypotension, CKD, hyperkalemia, acidosis, and anemia. ADTKD-MUC1 patients present only with CKD. This review describes the pathophysiology, genetics, clinical manifestation, and diagnosis for ADTKD, with an emphasis on genetic testing and genetic counseling suggestions for patients.

Review of genetic testing in kidney disease patients: Diagnostic yield of single nucleotide variants and copy number variations evaluated across and within kidney phenotype groups

Genetic kidney disease comprises a diverse group of disorders. These can roughly be divided in the phenotype groups congenital anomalies of the kidney and urinary tract, ciliopathies, glomerulopathies, stone disorders, tubulointerstitial kidney disease, and tubulopathies. Many etiologies can lead to chronic kidney disease that can progress to end-stage kidney disease. Despite each individual disease being rare, together these genetic disorders account for a large proportion of kidney disease cases. With the introduction of massively parallel sequencing, genetic testing has become more accessible, but a comprehensive analysis of the diagnostic yield is lacking. This review gives an overview of the diagnostic yield of genetic testing across and within the full range of kidney disease phenotypes through a systematic literature search that resulted in 115 included articles. Patient, test, and cohort characteristics that can influence the diagnostic yield are highlighted. Detection of copy number variations and their contribution to the diagnostic yield is described for all phenotype groups. Also, the impact of a genetic diagnosis for a patient and family members, which can be diagnostic, therapeutic, and prognostic, is shown through the included articles. This review will allow clinicians to estimate an a priori probability of finding a genetic cause for the kidney disease in their patients.

Autosomal dominant tubulointerstitial kidney disease: more than just HNF1β

Autosomal dominant tubulointerstitial kidney disease (ADTKD) refers to a group of disorders with a bland urinary sediment, slowly progressive chronic kidney disease (CKD), and autosomal dominant inheritance. Due to advances in genetic diagnosis, ADTKD is becoming increasingly recognized as a cause of CKD in both children and adults. ADTKD-REN presents in childhood with mild hypotension, CKD, hyperkalemia, acidosis, and anemia. ADTKD-UMOD is associated with gout and CKD that may present in adolescence and slowly progresses to kidney failure. HNF1β mutations often present in childhood with anatomic abnormalities such as multicystic or dysplastic kidneys, as well as CKD and a number of other extra-kidney manifestations. ADTKD-MUC1 is less common in childhood, and progressive CKD is its sole clinical manifestation, usually beginning in the late teenage years. This review describes the pathophysiology, genetics, clinical characteristics, diagnosis, and treatment of the different forms of ADTKD, with an emphasis on diagnosis. We also present data on kidney function in children with ADTKD from the Wake Forest Rare Inherited Kidney Disease Registry.

Factors that lead to dialysis as the preferred treatment modality for patients with chronic kidney disease

PURPOSE OF REVIEW

To describe forces that lead to dialysis as the preferred treatment modality for patients with chronic kidney disease.

RECENT FINDINGS

Although chronic dialysis is life-saving and the only option available for many individuals, treatment of the underlying causes of kidney disease and transplantation may be preferable options for many patients. Factors that favor dialysis instead of treatment of underlying kidney disease or transplantation include lack of proper diagnosis, lack of proper treatment of underlying kidney disease, poor compliance, lack of consideration for transplantation, early initiation of dialysis therapy, and financial incentives. New developments that may reverse this trend include genetic panels that improve diagnosis of kidney disease, new methods of transplantation, and legislation that will encourage kidney transplantation.

SUMMARY

By recognizing factors that favor dialysis over other therapies, nephrologists may be better able to provide care to their patients and prevent dialysis, researchers may be able to focus on research that will prevent the need for dialysis, and professional societies may work to prevent unneeded dialysis.

Plasma Mucin-1 (CA15-3) Levels in Autosomal Dominant Tubulointerstitial Kidney Disease due to MUC1 Mutations

INTRODUCTION

Patients with ADTKD-MUC1 have one allele producing normal mucin-1 (MUC1) and one allele producing mutant MUC1, which remains intracellular. We hypothesized that ADTKD-MUC1 patients, who have only 1 secretory-competent wild-type MUC1 allele, should exhibit decreased plasma mucin-1 (MUC1) levels. To test this hypothesis, we repurposed the serum CA15-3 assay used to measure MUC1 in breast cancer to measure plasma MUC1 levels in ADTKD-MUC1.

METHODS

This cross-sectional study analyzed CA15-3 levels in a reference population of 6,850 individuals, in 85 individuals with ADTKD-MUC1, and in a control population including 135 individuals with ADTKD-UMOD and 114 healthy individuals.

RESULTS

Plasma CA15-3 levels (mean ± standard deviation) were 8.6 ± 4.3 U/mL in individuals with ADTKD-MUC1 and 14.6 ± 5.6 U/mL in controls (p < 0.001). While there was a significant difference in mean CA15-3 levels, there was substantial overlap between the 2 groups. Plasma CA15-3 levels were <5 U/mL in 22% of ADTKD-MUC1 patients, in 0/249 controls, and in 1% of the reference population. Plasma CA15-3 levels were >20 U/mL in 1/85 ADTKD-MUC1 patients, in 18% of control individuals, and in 25% of the reference population. Segregation of plasma CA15-3 levels by the rs4072037 genotype did not significantly improve differentiation between affected and unaffected individuals. CA15-3 levels were minimally affected by gender and estimated glomerular filtration rate.

DISCUSSION/CONCLUSIONS

Plasma CA15-3 levels in ADTKD-MUC1 patients are approximately 40% lower than levels in healthy individuals, though there is significant overlap between groups. Further investigations need to be performed to see if plasma CA15-3 levels would be useful in diagnosis, prognosis, or assessing response to new therapies in this disorder.

Needs assessment study of rare diseases education for nurses and nursing students in Poland

Background

The treatment of rare diseases in contemporary health systems appears to be steadily gaining in importance, especially as the number of their occurrence is increasing. However, the education of medical staff in their correct diagnosis and therapy seems inadequate. Our study aims to analyze the knowledge and opinions concerning rare diseases among Polish nurses and nursing students.

Methods

We analyzed a group of 142 nurses and 113 nursing students, using a questionnaire comprising 28 questions about the number, examples, etiology and estimated frequency of rare diseases. Self-assessment of one’s own theoretical and practical competence in the topic, as well as the opinion of the respondents on the need for a more prominent place of rare diseases in the curricula of medical universities, were also tested. We also asked about our informants’ sources of information on rare diseases. The study was conducted between January and June 2019.

Results

Although only approximately $$ \raisebox{1ex}{$1$}\!\left/ \!\raisebox{-1ex}{$3$}\right. $$ 1 3 rd of respondents declared having participated in university classes in rare diseases, a markedly higher number (~ 85% of nurses and ~ 75% of students) sees the need for such courses. Neither group feels well-prepared to deal with patients with rare diseases, with 75% of nurses and as many as 85% of nursing students expressing their concern in this respect. Both groups name the Internet as their major source of information.

Conclusion

Both nurses and nursing students show insufficient knowledge of rare diseases, though the level of competence of the former is in many respects higher in a statistically significant way. Most respondents perceive serious deficiencies in their preparation to care for such patients. A change in university curricula seems much called for.

Genetic and Clinical Predictors of Age of ESKD in Individuals With Autosomal Dominant Tubulointerstitial Kidney Disease Due to UMOD Mutations

INTRODUCTION

Autosomal dominant tubulo-interstitial kidney disease due to UMOD mutations (ADTKD-UMOD) is a rare condition associated with high variability in the age of end-stage kidney disease (ESKD). The minor allele of rs4293393, located in the promoter of the UMOD gene, is present in 19% of the population and downregulates uromodulin production by approximately 50% and might affect the age of ESKD. The goal of this study was to better understand the genetic and clinical characteristics of ADTKD-UMOD and to perform a Mendelian randomization study to determine if the minor allele of rs4293393 was associated with better kidney survival.

METHODS

An international group of collaborators collected clinical and genetic data on 722 affected individuals from 249 families with 125 mutations, including 28 new mutations. The median age of ESKD was 47 years. Men were at a much higher risk of progression to ESKD (hazard ratio 1.78, P < 0.001).

RESULTS

The allele frequency of the minor rs4293393 allele was only 11.6% versus the 19% expected (P < 0.01), resulting in Hardy-Weinberg disequilibrium and precluding a Mendelian randomization experiment. An in vitro score reflecting the severity of the trafficking defect of uromodulin mutants was found to be a promising predictor of the age of ESKD.

CONCLUSION

We report the clinical characteristics associated with 125 UMOD mutations. Male gender and a new in vitro score predict age of ESKD.

Needs assessment study of rare diseases education for nurses and nursing students in Poland

BACKGROUND

The treatment of rare diseases in contemporary health systems appears to be steadily gaining in importance, especially as the number of their occurrence is increasing. However, the education of medical staff in their correct diagnosis and therapy seems inadequate. Our study aims to analyze the knowledge and opinions concerning rare diseases among Polish nurses and nursing students.

METHODS

We analyzed a group of 142 nurses and 113 nursing students, using a questionnaire comprising 28 questions about the number, examples, etiology and estimated frequency of rare diseases. Self-assessment of one's own theoretical and practical competence in the topic, as well as the opinion of the respondents on the need for a more prominent place of rare diseases in the curricula of medical universities, were also tested. We also asked about our informants' sources of information on rare diseases. The study was conducted between January and June 2019.

RESULTS

Although only approximately [Formula: see text]rd of respondents declared having participated in university classes in rare diseases, a markedly higher number (~ 85% of nurses and ~ 75% of students) sees the need for such courses. Neither group feels well-prepared to deal with patients with rare diseases, with 75% of nurses and as many as 85% of nursing students expressing their concern in this respect. Both groups name the Internet as their major source of information.

CONCLUSION

Both nurses and nursing students show insufficient knowledge of rare diseases, though the level of competence of the former is in many respects higher in a statistically significant way. Most respondents perceive serious deficiencies in their preparation to care for such patients. A change in university curricula seems much called for.