Clinical and molecular characterization of a large primary hyperoxaluria cohort from Saudi Arabia: a retrospective study.

BACKGROUND: Primary hyperoxalurias (PHs) constitute rare disorders resulting in abnormal glyoxalate metabolism. PH-associated phenotypes range from progressive nephrocalcinosis and/or recurrent urolithiasis to early kidney failure. METHODS: A retrospective study was conducted for patients with confirmed PH diagnoses from three tertiary centers in Saudi Arabia. Detailed clinical molecular diagnosis was performed for 25 affected individuals. Whole exome sequencing (WES)-based molecular diagnosis was performed for all affected individuals. RESULTS: The male:female ratio was 52% male (n = 13) and 48% female (n = 12), and consanguinity was present in 88%. Nephrolithiasis and/or nephrocalcinosis were present in all patients. Kidney stones were present in 72%, nephrocalcinosis in 60%, hematuria in 32%, proteinuria in 16%, abdominal pain in 36%, developmental delay in 8%, and chronic kidney disease stage 5 (CKD stage 5) was observed in 28% of the patients. The most common PH disorder was type I caused by variants in the AGXT gene, accounting for 56%. The GRHPR gene variants were identified in 4 patients, 16% of the total cases. Seven patients did not reveal any associated variants. Missense variants were the most commonly observed variants (48%), followed by frame-shift duplication variants (28%). CONCLUSIONS: Characterization of the genetic and clinical aspects of PH in this unique population provides direction for improved patient management and further research. A higher resolution version of the Graphical abstract is available as Supplementary information.

Renal lymphangiomatosis, a rare differential diagnosis for autosomal recessive polycystic kidney disease in pediatric patients.

Renal lymphangiomatosis is a rare, benign malformation, characterized by developmental malformation of the perirenal, peripelvic, and intrarenal lymphatics. Radiologist knowledge of the unique radiological features of this entity helps patient's safety in terms of management. We study the case of a 27-month-old boy presented to the emergency department with upper respiratory tract infection. He had a high blood pressure and had been diagnosed earlier with autosomal recessive polycystic kidney disease based on renal ultrasound findings. Because the clinical presentation and laboratory work of the patient did not support the diagnosis of autosomal recessive polycystic kidney disease, further, extensive work-up was performed, which confirmed the diagnosis of renal lymphangiomatosis. This case report emphasizes the imaging features of this rare entity to promote early diagnosis and better patient care.

Delineation of cystinuria in Saudi Arabia: A case series.

BACKGROUND: Cystinuria is an inherited metabolic disease that is caused by defects in two genes, SLC3A1 and SLC7A9, which result in a renal reabsorptive defect of cystine and other dibasic amino acids, including ornithine, arginine, and lysine. Patients usually present with recurrent renal calculi and may develop renal impairment. Medical management includes high fluid intake and chelating agents. To the best of our knowledge, this is the first study describing cystinuria in Saudi Arabia. METHODS: A retrospective chart review for cystinuria patients from the genetic and nephrology divisions between 2010 to 2015. All patients were investigated, diagnosed and treated at King Abdulaziz Medical City in Saudi Arabia. RESULTS: Eight patients were identified from five unrelated families. The age of onset ranged from birth to 14 years. The female to male ratio was 1.7:1. Two new variants in the SLC3A1 and SLC9A7 genes were discovered. All of the detected mutations were missense variants in three different exons, such as c.1711 T > A (p.Cys571Ser) (exon 10), c.1166C > T p.Thr389Met (exon 11) and c.1400 T > A p.Met467Lys (exon 8). Additionally, 37.5% of our patients developed arterial hypertension and 25% had urinary tract infection, but none had renal impairment. No significant clinical differences were detected in this study between type A (SLC3A1 variants) and type B cystinuria (SLC7A9 variant). Two cases were diagnosed based on clinical information, biochemical testing and a positive family history as all of the molecular testing for cystinuria was negative. CONCLUSION: Cystinuria has wide genetic heterogeneity with a poor genotype/phenotype correlation. Negative molecular investigations should not rule out the disease if clinical and biochemical investigations support the diagnosis. A larger data registry is essential to better describe the cystinuria genotype/phenotype in Saudi Arabia.

Acute diffuse proliferative post-infectious glomerulonephritis in renal allograft--a case report and literature review.

PVN is a well-known cause of renal allograft dysfunction and failure. The diagnosis is established by examination of tissue from the renal graft, and confirmed by immunohistochemical or in situ hybridization techniques. Electron microscopy can be utilized as an ancillary modality to identify the viral particles ultrastructurally. The tubular epithelial cells are the primary target of PV cytopathic effect; however, PV-associated glomerular changes have also been described. Immune-type electron-dense deposits in the TBMs have been described in the setting of PVN, and rarely, likewise have glomerular subepithelial hump-like deposits. Diffuse immune-mediated proliferative glomerulonephritis in the setting of PVN has not been reported before. In this report, we describe an 11-yr-old kidney transplant recipient boy who developed immune-mediated glomerulonephritis with light microscopic, immunofluorescence, and ultrastructural features compatible with acute PIGN superimposing chronic PVN, discuss this unusual association and the possible mechanisms of antigen clearance in PVN and present a literature review.

Extreme intrafamilial variability of Saudi brothers with primary hyperoxaluria type 1.

BACKGROUND: Primary hyperoxaluria type 1 (PH1) is characterized by progressive renal insufficiency culminating in end-stage renal disease, and a wide range of clinical features related to systemic oxalosis in different organs. It is caused by autosomal recessive deficiency of alanine:glyoxylate aminotransferase due to a defect in AGXT gene. CASE REPORT: Two brothers (one 6 months old; the other 2 years old) presented with acute renal failure and urinary tract infection respectively. PH1 was confirmed by high urinary oxalate level, demonstration of oxalate crystals in bone biopsy, and pathogenic homozygous known AGXT gene mutation. Despite the same genetic background, same sex, and shared environment, the outcome of the two siblings differs widely. While one of them died earlier with end-stage renal disease and multiorgan failure caused by systemic oxalosis, the older brother is pyridoxine responsive with normal development and renal function. CONCLUSION: Clinicians should be aware of extreme intrafamilial variability of PH1 and international registries are needed to characterize the genotype-phenotype correlation in such disorder.

The value of renal ultrasound in children with a first episode of urinary tract infection.

BACKGROUND: Urinary tract infection (UTI) is a common pediatric problem. Guidelines recommend obtaining a renal ultrasonogram (RUS) for young children after a first UTI. Our aim was to assess the value of routine RUS in the management of children hospitalized with a first episode of UTI. METHODS: We conducted a retrospective review of the medical records of 130 children 12 years of age or younger admitted with a first UTI. Children were excluded if they had a urinary tract abnormality before admission and/or had been treated with an antibacterial agent within 7 days before admission. The yield of RUS was measured by ability to detect renal abnormalities, by the sensitivity and specificity for detecting vesicoureteral reflux (VUR) using voiding cystourethrogram (VCUG) as a gold standard, and by its influence on UTI management. RESULTS: RUS was conducted in 130 children, but only 118 returned for a VCUG and were included in the study. The findings were positive for VUR in 20 of 40 patients (50%) with a confirmed VUR on VCUG and positive in 18 of 78 patients (23.1%) without VUR on VCUG. Of the 20 patients with a normal RUS who showed VUR, 2 had grade I reflux, 8 had grade II reflux, 7 had grade III reflux and 3 had grade IV reflux. The sensitivity, specificity, positive and negative predictive value of ultrasound in suggesting VUR was 50% and 76.9%, 52.6% and 75%, respectively. Except for one, the result of an abnormal RUS did not alter the management of our patients. CONCLUSION: The results of our study show that the RUS has a little value in the management of children with a first UTI.