Stroke in primary hyperoxaluria type I

The real world experience of pediatric primary hyperoxaluria patients in the PEDSnet clinical research network

The rarity of primary hyperoxaluria (PH) challenges our understanding of the disease. The purpose of our study was to describe the course of clinical care in a United States cohort of PH pediatric patients, highlighting health service utilization. We performed a retrospective cohort study of PH patients < 18 years old in the PEDSnet clinical research network from 2009 to 2021. Outcomes queried included diagnostic imaging and testing related to known organ involvement of PH, surgical and medical interventions specific to PH-related renal disease, and select PH-related hospital service utilization. Outcomes were evaluated relative to cohort entrance date (CED), defined as date of first PH-related diagnostic code. Thirty-three patients were identified: 23 with PH type 1; 4 with PH type 2; 6 with PH type 3. Median age at CED was 5.0 years (IQR 1.4, 9.3 years) with the majority being non-Hispanic white (73%) males (70%). Median follow-up between CED and most recent encounter was 5.1 years (IQR 1.2, 6.8). Nephrology and Urology were the most common specialties involved in care, with low utilization of other sub-specialties (12%-36%). Most patients (82%) had diagnostic imaging used to evaluate kidney stones; 11 (33%) had studies of extra-renal involvement. Stone surgery was performed in 15 (46%) patients. Four patients (12%) required dialysis, begun in all prior to CED; four patients required renal or renal/liver transplant.    Conclusion: In this large cohort of U.S. PH children, patients required heavy health care utilization with room for improvement in involving multi-disciplinary specialists. What is Known: • Primary hyperoxaluria (PH) is rare with significant implications on patient health. Typical involvement includes the kidneys; however, extra-renal manifestations occur. • Most large population studies describe clinical manifestations and involve registries. What is New: • We report the clinical journey, particularly related to diagnostic studies, interventions, multispecialty involvement, and hospital utilization, of a large cohort of PH pediatric patients in the PEDSnet clinical research network. • There are missed opportunities, particularly in that of specialty care, that could help in the diagnosis, treatment, and even prevention of known clinical manifestations.

Antiphospholipid-negative Sneddon's syndrome: A comprehensive overview of a rare entity

The term Sneddon's syndrome (SS) has been used since 1965 to describe a vasculopathy characterized by a combination of cerebrovascular disease with livedo racemosa. SS may be classified as antiphospholipid+ (aPL+) or antiphospholipid- (aPL-). Little is known about aPL- SS; in this review we describe the epidemiology and pathogenesis of aPL- SS, as well as the clinical and histologic features. We discuss recent findings in terms of neurologic and cardiac involvement. Moreover, differential diagnoses of conditions that may present with both livedo racemosa and stroke are discussed. Finally, we discuss real-life practical issues such as the initial investigations to be performed, long-term follow-up, and therapeutic management of aPL- SS patients.

Long-term complications of systemic oxalosis in children-a retrospective single-center cohort study

BACKGROUND

Systemic oxalosis is a severe complication seen in primary hyperoxaluria type I patients with kidney failure. Deposition of insoluble calcium oxalate crystals in multiple organs leads to significant morbidity and mortality.

METHODS

We describe a retrospective cohort of 11 patients with systemic oxalosis treated at our dialysis unit from 1982 to 1998 (group 1) and 2007-2019 (group 2). Clinical and demographic data were collected from medical records. Imaging studies were only available for patients in group 2 (n = 5).

RESULTS

Median age at dialysis initiation was 6.1 months (IQR 4-21.6), 64% were male. Dialysis modality was mostly peritoneal dialysis in group 1 and daily hemodialysis in group 2. Bone disease was the first manifestation of systemic oxalosis, starting with the appearance of sclerotic bands (mean 166 days, range 1-235), followed by pathological fractures in long bones (mean 200.4 days, range 173-235 days). Advanced disease was characterized by vertebral fractures with resulting kyphosis, worsening splenomegaly, and adynamic bone disease. Two patients developed pulmonary hypertension, 4 and 8 months prior to their death. Four of 11 patients developed hypothyroidism 0-60 months after dialysis initiation. Only one patient survived after a successful liver-kidney transplantation. Four patients died after liver or liver-kidney transplantation.

CONCLUSIONS

This is the first comprehensive description of the natural history of pediatric systemic oxalosis. We hope that our findings will provide basis for a quantitative severity score in future, larger studies.

Oxalates, urinary stones and risk of cardiovascular diseases

Increased level of oxalates in urine and plasma can be attributed to endogenous overproduction, increased ingestion or excessive intestinal absorption. When a supersaturation status is reached, oxalates combine with calcium and crystallize to form 80% of the urinary stones. Several cardiovascular diseases such as coronary heart disease and stroke are thought to be associated with the formation of urinary stones via sharing the same pathogenesis and/or risk factors. This review investigated the evidence linking oxalates/urinary stones to cardiovascular diseases. Eventually, two theories can explain the possible association between urinary stones and cardiovascular diseases: the theory of common origin and the theory of common risk factors. While the first theory is based on the common vascular pathophysiology of urinary stones and cardiac events, the later suggests that metabolic syndrome traits increase the risk of urinary stones and cardiovascular diseases independently. A few cohort studies showed a higher risk of coronary heart disease and stroke among people with history of urinary stones than people without it while other cohort studies did not. These studies had different definitions for cardiovascular diseases, used various methods to assess urinary stones, and some of them did not control for potential confounders. When they were pooled together in meta-analyses, a significant heterogeneity across studies was observed. In conclusion, although there is some evidence indicating that urinary stones could increase the risk of cardiovascular diseases, a substantial causal relationship cannot be settled.

Combined liver-kidney transplantation for primary hyperoxaluria type I in children: Single Center Experience

Primary hyperoxalurias are rare inborn errors of metabolism with deficiency of hepatic enzymes that lead to excessive urinary oxalate excretion and overproduction of oxalate which is deposited in various organs. Hyperoxaluria results in serious morbid-ity, end stage kidney disease (ESKD), and mortality if left untreated. Combined liver kidney transplantation (CLKT) is recognized as a management of ESKD for children with hyperoxaluria type 1 (PH1). This study aimed to report outcome of CLKT in a pediatric cohort of PH1 patients, through retrospective analysis of data of 8 children (2 girls and 6 boys) who presented by PH1 to Wadi El Nil Pediatric Living Related Liver Transplant Unit during 2001-2017. Mean age at transplant was 8.2 ± 4 years. Only three of the children underwent confirmatory genotyping. Three patients died prior to surgery on waiting list. The first attempt at CLKT was consecutive, and despite initial successful liver transplant, the girl died of biliary peritonitis prior to scheduled renal transplant. Of the four who underwent simultaneous CLKT, only two survived and are well, one with insignificant complications, and other suffered from abdominal Burkitt lymphoma managed by excision and resection anastomosis, four cycles of rituximab, cyclophosphamide, vincristine, and prednisone. The other two died, one due to uncontrollable bleeding within 36 hours of procedure, while the other died awaiting renal transplant after loss of renal graft to recurrent renal oxalosis 6 months post-transplant. PH1 with ESKD is a rare disease; simultaneous CLKT offers good quality of life for afflicted children. Graft shortage and renal graft loss to oxalosis challenge the outcome.

Primary hyperoxaluria: spectrum of clinical and imaging findings

Primary hyperoxaluria is a rare autosomal recessive inborn error of metabolism with three known subtypes. In primary hyperoxaluria type 1, the most common of the subtypes, a deficiency in the hepatic enzymes responsible for the metabolism of glycoxylate to glycine, leads to excessive levels of glyoxylate, which is converted to oxalate. The resultant elevation in serum and urinary oxalate that characterizes primary hyperoxaluria leads to calcium oxalate crystal deposition in multiple organ systems (oxalosis). We review the genetics, pathogenesis, variable clinical presentation and course of this disease as well as its treatment. Emphasis is placed on the characteristic imaging findings before and after definitive treatment with combined liver and renal transplantation.

Genome-Wide Association Study with Targeted and Non-targeted NMR Metabolomics Identifies 15 Novel Loci of Urinary Human Metabolic Individuality

Genome-wide association studies with metabolic traits (mGWAS) uncovered many genetic variants that influence human metabolism. These genetically influenced metabotypes (GIMs) contribute to our metabolic individuality, our capacity to respond to environmental challenges, and our susceptibility to specific diseases. While metabolic homeostasis in blood is a well investigated topic in large mGWAS with over 150 known loci, metabolic detoxification through urinary excretion has only been addressed by few small mGWAS with only 11 associated loci so far. Here we report the largest mGWAS to date, combining targeted and non-targeted ¹H NMR analysis of urine samples from 3,861 participants of the SHIP-0 cohort and 1,691 subjects of the KORA F4 cohort. We identified and replicated 22 loci with significant associations with urinary traits, 15 of which are new (HIBCH, CPS1, AGXT, XYLB, TKT, ETNPPL, SLC6A19, DMGDH, SLC36A2, GLDC, SLC6A13, ACSM3, SLC5A11, PNMT, SLC13A3). Two-thirds of the urinary loci also have a metabolite association in blood. For all but one of the 6 loci where significant associations target the same metabolite in blood and urine, the genetic effects have the same direction in both fluids. In contrast, for the SLC5A11 locus, we found increased levels of myo-inositol in urine whereas mGWAS in blood reported decreased levels for the same genetic variant. This might indicate less effective re-absorption of myo-inositol in the kidneys of carriers. In summary, our study more than doubles the number of known loci that influence urinary phenotypes. It thus allows novel insights into the relationship between blood homeostasis and its regulation through excretion. The newly discovered loci also include variants previously linked to chronic kidney disease (CPS1, SLC6A13), pulmonary hypertension (CPS1), and ischemic stroke (XYLB). By establishing connections from gene to disease via metabolic traits our results provide novel hypotheses about molecular mechanisms involved in the etiology of diseases.

Human metabolism is influenced by genetic and environmental factors defining a person’s metabolic individuality. This individuality is linked to personal differences in the ability to react on metabolic challenges and in the susceptibility to specific diseases. By investigating how common variants in genetic regions (loci) affect individual blood metabolite levels, the substantial contribution of genetic inheritance to metabolic individuality has been demonstrated previously. Meanwhile, more than 150 loci influencing metabolic homeostasis in blood are known. Here we shift the focus to genetic variants that modulate urinary metabolite excretion, for which only 11 loci were reported so far. In the largest genetic study on urinary metabolites to date, we identified 15 additional loci. Most of the 26 loci also affect blood metabolite levels. This shows that the metabolic individuality seen in blood is also reflected in urine, which is expected when urine is regarded as “diluted blood”. Nonetheless, we also found loci that appear to primarily influence metabolite excretion. For instance, we identified genetic variants near a gene of a transporter that change the capability for renal re-absorption of the transporter’s substrate. Thus, our findings could help to elucidate molecular mechanisms influencing kidney function and the body’s detoxification capabilities.