Female with Fabry Disease Unknowingly Donates Affected Kidney to Sister: A Call for Pre-transplant Genetic Testing

Genetic Assessment of Living Kidney Transplant Donors: A Survey of Canadian Practices

Background

Kidney failure is a prevalent condition with tendency for familial clustering in up to 27% of the affected individuals. Living kidney donor (LKD) transplantation is the optimal treatment option; however, in Canada, more than 45% of LKDs are biologically related to their recipients which subjects recipients to worse graft survival and donors to higher future risk of kidney failure. Although not fully understood, this observation could be partially explained by genetic predisposition to kidney diseases. Genetic testing of potential LKDs may improve risk assessment and inform the safety of donation. The strategies to evaluate these donors are still evolving. In Canada, little is known about the practice of assessing for genetic conditions among LKDs.

Aim

The aim was to examine the Canadian practices regarding LKDs genetic assessment.

Methods

Questionnaires were sent to 23 Canadian adult transplant centers to examine their protocols for LKDs genetic assessment.

Design

The questionnaire comprised of 10 sections and 21 questions including case scenarios of different LKD encounters. Major domains of the survey addressed general demographics, information sharing practices, effect of mode of inheritance on candidacy decision, having a policy for LKD genetic evaluation, and case scenarios covering the following conditions: autosomal dominant polycystic kidney disease (ADPKD), Alport syndrome, Fabry disease, familial focal and segmental glomerulosclerosis (FSGS), atypical hemolytic uremic syndrome (aHUS), autosomal dominant tubulointerstitial kidney disease (ADTKD), sickle cell, and apolipoprotein L1 mutation (APOL1).

Participants

The questionnaire was sent to the living-donor assessment committee representative (nephrologist) in adult and pediatric kidney transplant centers across Canada.

Results

In total, 16 of 23 Canadian centers responded to the survey. Of the 8 surveyed genetic conditions, ADPKD, Alport syndrome, and aHUS were the most frequently encountered. More centers have specific policies for donor evaluation for ADPKD (25%) and aHUS (21.4%) vs none to very few for other genetic conditions. The most cited guidelines are Kidney Disease Improving Global Outcomes (KDIGO), Canadian Society of Nephrology/Canadian Society of Transplantation (CSN/CST), and the Canadian Blood Services' Kidney Paired Donation Protocol.

Conclusions

Canadian transplant centers follow a case-by-case approach rather than a standard protocol for genetic assessment of LKDs given that current guideline recommendations are based on expert opinion due to a lack of a reliable body of evidence. With the expected rise in utilization of the increasingly available genetic testing, early multidisciplinary assessment including medical geneticists has the potential to improve personalized management. Studies examining long-term donor and graft outcomes are needed to construct the basis for evidence-based recommendations and inform the safety of donations.

Outcomes and management of kidney transplant recipients with Fabry disease: a review

Fabry disease is an X-linked inheritable lysosomal storage disease caused by various mutations of the galactosidase α gene resulting in α-galactosidase deficiency. Chronic kidney disease (CKD) is one of the most significant consequences of Fabry disease, with risk of end-stage kidney disease (ESKD) in this population. Like for other patients with ESKD, kidney transplant is the optimal treatment for Fabry disease patients with ESKD. However, enzyme replacement therapy and newer Fabry disease treatments remain important to mitigate other end organ damage such as cardiomyopathy post transplantation. This review is a primer on Fabry disease, which examines the outcomes of disease in the context of kidney transplant prior to, and during, the enzyme replacement treatment era, medical treatment of kidney transplant recipients with Fabry disease, and progress in screening studies.

The evolving role of diagnostic genomics in kidney transplantation

Monogenic forms of heritable kidney disease account for a significant proportion of chronic kidney disease (CKD) across both pediatric and adult patient populations and up to 11% of patients under 40 years reaching end-stage kidney failure (KF) and awaiting kidney transplant. Diagnostic genomics in the field of nephrology is ever evolving and now plays an important role in assessment and management of kidney transplant recipients and their related donor pairs. Genomic testing can help identify the cause of KF in kidney transplant recipients and assist in prognostication around graft survival and rate of recurrence of primary kidney disease. If a gene variant has been identified in the recipient, at-risk related donors can be assessed for the same and excluded if affected. This paper aims to address the indications for genomic testing in the context for kidney transplantation, the technologies available for testing, the conditions and groups in which testing should be most often considered, and the role for the renal genetics multidisciplinary team in this process.

A case of latent heterozygous Fabry disease in a female living kidney donor candidate

A 52-year-old woman had been found to have hematuria at her annual checkup 5 years in a row. She hoped to donate her kidney to her husband, so we performed a percutaneous kidney biopsy at our department. It was difficult for us to detect apparent abnormalities under a light microscopic examination, and she was determined to meet the eligibility criteria for living kidney transplantation. However, the sample for electron microscopy was not evaluated before kidney donation. She subsequently underwent living kidney transplantation as a donor. A 1-h biopsy revealed swelling and obvious vacuolation of the glomerular podocytes, which were characteristic of Fabry disease. Her medical history and examinations were reviewed. No findings or episodes were observed. Pre-donation electronmicroscopy revealed numerous zebra bodies in the podocytes. A definite diagnosis of heterozygous Fabry disease was made based on the GLA gene mutation despite the normal range of leukocyte α-Gal A activity. Based on the pathological deposition of GL-3, chaperone therapy was initiated to suppress the progression of organ damage. In this case, we could not confirm a diagnosis of Fabry disease despite performing a renal biopsy prior to kidney donation. Kidney donor candidates may sometimes have factors that cannot be assumed based on medical or family history. Thus, it is important to perform a renal biopsy before kidney donation when necessary, and to always conduct a detailed evaluation including electron microscopy.

Effectiveness of plasma lyso-Gb3 as a biomarker for selecting high-risk patients with Fabry disease from multispecialty clinics for genetic analysis

PURPOSE

Plasma globotriaosylsphingosine (lyso-Gb3) is a promising secondary screening biomarker for Fabry disease. Here, we examined its applicability as a primary screening biomarker for classic and late-onset Fabry disease in males and females.

METHODS

Between 1 July 2014 and 31 December 2015, we screened 2,359 patients (1,324 males) referred from 168 Japanese specialty clinics (cardiology, nephrology, neurology, and pediatrics), based on clinical symptoms suggestive of Fabry disease. We used the plasma lyso-Gb3 concentration, α-galactosidase A (α-Gal A) activity, and analysis of the α-Gal A gene (GLA) for primary and secondary screens, respectively.

RESULTS

Of 8 males with elevated lyso-Gb3 levels (≥2.0 ng ml-1) and low α-Gal A activity (≤4.0 nmol h-1 ml-1), 7 presented a GLA mutation (2 classic and 5 late-onset). Of 14 females with elevated lyso-Gb3, 7 displayed low α-Gal A activity (5 with GLA mutations; 4 classic and 1 late-onset) and 7 exhibited normal α-Gal A activity (1 with a classic GLA mutation and 3 with genetic variants of uncertain significance).

CONCLUSION

Plasma lyso-Gb3 is a potential primary screening biomarker for classic and late-onset Fabry disease probands.

Fabry's Disease: Case Series and Review of Literature

Fabry's disease is an X-linked lysosomal storage disorder caused by a deficiency of alpha-galactosidase A enzyme with the progressive accumulation of globotriaosylceramide in vascular endothelial cells leading to cardiovascular, renal, gastrointestinal, neuropathic, lenticular, and dermatological manifestations. It is a rare cause of end-stage renal disease. It classically affects males whereas 10-15% of female heterozygote carriers are affected depending on localization. Both the FD and its association with ESRD is rare. With this background, this case series of five patient's along with the review of literature is presented here.

Unexpectedly high prevalence of rare genetic disorders in kidney transplant recipients with an unknown causal nephropathy

BACKGROUND

Patients with a rare genetic disease may receive renal transplantation (KTx) without a correct diagnosis of causal nephropathy and therefore develop unexpected and even severe complications. The aim of the study was to describe the cases of rare genetic disorders diagnosed after KTx, in order to draw clinical lessons for the transplant physician.

METHODS

We retrospectively assessed all patients who had received a diagnosis of a rare genetic disorder after KTx.

RESULTS

In our center, more than 30% (278/911) of kidney transplant (KTx) recipients were diagnosed with a causal nephropathy: Prevalence of rare genetic disorders in this group was 4.32% (12/278), including 2,8-dihydroxyadeninuria (2,8-DHA) disease (n = 2), HNF-1B-associated nephropathy (n = 2), UMOD-related nephropathy (n = 5), Fabry disease (n = 1), INF2 focal segmental glomerulosclerosis (n = 1), and Senior-Løken syndrome (n = 1). 2,8-DHA nephropathy relapsed in both patients causing an acute renal failure and jeopardizing the graft.

CONCLUSIONS

Kidney transplant recipients without a diagnosis of causal nephropathy appear to be a selected population in which rare genetic diseases might be more common than expected. As even a belated diagnosis after KTx can have a significant impact on graft and patient survival and on other family members, this possibility should be evaluated in KTx recipients without a known causal nephropathy.