Lumasiran treatment in pediatric patients with PH1: real-world data within a compassionate use program in Italy.

Background: Primary hyperoxaluria (PH) is a rare, severe genetic disorder, characterized by increased urinary excretion of calcium oxalate, which is responsible for kidney damage and systemic clinical manifestations. Since the year 2020, a new molecule, lumasiran, based on RNA interference (RNAi) technology, has been added to the traditional therapeutic approach. The aim of this analysis was to define the baseline characteristics of a PH1 pediatric population treated with lumasiran in a compassionate-use program setting, and to evaluate the medium-term efficacy of this drug in the routine clinical setting. Methods: A retrospective observational analysis was conducted in nine pediatric patients (male:female 5:4; median age at lumasiran start 1.9 years, range 0-14.1). Data concerning oxalate concentration in plasma and urine, kidney stones events, ultrasound and kidney function were collected during the study period (follow-up, mean ± standard deviation: 15.3 ± 5 months). Results: In this analysis, a reduction in the urinary oxalate to creatinine ratio (reduction range within the sixth month of treatment from 25.8% to 69.6%, median 51.2%) as well as plasma oxalate concentration under the limit of supersaturation of oxalate in all the patients. Only one patient presented new stone events; kidney ultrasonographic findings related to nephrocalcinosis remained stable in eight out of nine patients. Glomerular filtration rate remained stable during treatment. No adverse events related to lumasiran were noted. Conclusion: Data from this analysis support the efficacy and safety of lumasiran in a pediatric clinical setting, especially if administrated in early life.

Uromodulin and Vesico-Ureteral Reflux: A Genetic Study.

Vesicoureteral reflux (VUR) is associated with urinary tract infections (UTI) and renal scars. The kidney damage is correlated with the grade of reflux and the number of UTI, but other factors may also play a role. Uromodulin (UMOD) is a protein produced by kidney tubular cells, forming a matrix in the lumen. We evaluated whether the common variant rs4293393 in the UMOD gene was associated with febrile UTI (FUTI) and/or scars in a group of children with VUR. A total of 31 patients with primary VUR were enrolled. Renal scars were detected in 16 children; no scar was detected in 15 children. Genotype rs4293393 TC (TC) was present in 8 patients, 7 (88%) had scars; genotype rs4293393 TT (TT) was found in 23 patients, and 9 (39%) had scars. Among children with scars, those with TC compared with those with TT were younger (mean age 77 vs. 101 months), their reflux grade was comparable (3.7 vs. 3.9), and the number of FUTI was lower (2.9 vs. 3.7 per patient). Children with VUR carrying UMOD genotype rs4293393 TC seem more prone to developing renal scars, independent of FUTI.

A novel NF1 mutation in a pediatric patient with renal artery aneurysm.

BACKGROUND: Neurofibromatosis type 1 (NF1) is a neurocutaneous syndrome, due to heterozygous pathogenic variants in NF1 gene. The main clinical manifestations are multiple café au lait spots, axillary and inguinal freckling, cutaneous and plexiform neurofibromas, optic glioma, Lisch nodules and osseous lesions, such as sphenoid and tibial dysplasia. Vasculopathy is another feature of NF1; it consists of stenosis, aneurysms, and arteriovenous malformations, frequently involving renal arteries. CASE PRESENTATION: We report on a 9-year-old girl with a novel mutation in NF1 gene and renal artery aneurysm, treated by coil embolization and complicated with hypertension. CONCLUSION: Vasculopathy is a complication of NF1, affecting from 0.4 to 6.4% of patients with NF1. Among the vascular abnormalities, renal artery aneurysm is a rare manifestation, with only a few cases regarding adult patients and no pediatric reports described in current literature. The finding of a vascular abnormality in a specific site requires the evaluation of the entire vascular system because multiple vessels could be involved at the same time.

Hypertrophic pyloric stenosis masked by kidney failure in a male infant with a contiguous gene deletion syndrome at Xp22.31 involving the steroid sulfatase gene: case report.

BACKGROUND: Contiguous gene deletion syndrome at Xp22.3 resulting in nullisomy in males or Turner syndrome patients typically encompasses the steroid sulfatase gene (STS) and contiguously located other genes expanding the phenotype. In large deletions, that encompass also the Kallmann syndrome 1 gene (KAL1), occasionally infantile hypertrophic pyloric stenosis (IHPS) and congenital anomalies of the kidney and urinary tract (CAKUT) have been reported. PATIENT PRESENTATION: We report on a male newborn with family history in maternal uncle of renal abnormalities and short stature still without ichthyosiform dermatosis. The baby presented CAKUT with kidney failure and progressive vomiting. Renal bicarbonate loss masked hypochloremic and hypokalemic metabolic alkalosis classically present in IHPS and delayed its diagnosis. Antropyloric ultrasound examination and cystourethrography were diagnostic. After Fredet-Ramstedt extramucosal pyloromyotomy feeding and growing was regular and he was discharged home. Comparative whole-genome hybridization detected a maternal inherited interstitial deletion of 1.56 Mb on Xp22.31(6,552,712_8,115,153) × 0 involving the STS gene, but not the KAL1 gene. CONCLUSIONS: Aberrant cholesterol sulfate storage due to STS deletion as the underlying pathomechanism is not limited to oculocutaneous phenotypes but could also lead to co-occurrence of both IHPS and kidney abnormalities, as we report. Thus, although these two latter pathologies have a high incidence in the neonatal age, their simultaneous association in our patient is resembling not a chance but a real correlation expanding the clinical spectrum associated with Xp22.31 deletions.

Primary hyperoxaluria in Italy: the past 30 years and the near future of a (not so) rare disease.

BACKGROUND: Primary hyperoxalurias (PHs) are rare autosomal recessive diseases of the glyoxylate metabolism; PH1 is caused by mutations in the AGXT gene, PH2 in GRHPR and PH3 in HOGA1. METHODS: Here we report the first large multi-center cohort of Italian PH patients collected over 30 years (1992-2020 median follow-up time 8.5 years). Complete genotype was available for 94/95 PH1 patients and for all PH2 (n = 3) and PH3 (n = 5) patients. Symptoms at onset were mainly nephrolithiasis (46.3%) and nephrocalcinosis (33.7%). Median age at onset of symptoms and diagnosis were 4.0 years and 9.9 years, respectively. RESULTS: Fifty-four patients (56.8%) were diagnosed after chronic kidney disease. Sixty-three patients (66.3%) developed end stage kidney disease (median age 14.0 years). Twenty-one patients had a kidney-only transplant and, among them, seven had a second kidney transplant combined with liver transplant. A combined kidney-liver transplant was carried out in 29 patients and a sequential kidney-liver transplant was performed in two. In five cases a preemptive liver transplant was performed. Those receiving a liver-only transplant tended to have lower kidney function at last follow-up. CONCLUSION: Our study of PHs in Italy underlines a considerable diagnostic delay, which has only slightly decreased in recent years. Therefore, we suggest a more extensive use of both metabolic screening among patients with recurrent kidney stones and genotyping, including unambiguous assignment of minor/major allele status in order to promptly begin appropriate treatment. This will be fundamental in order to have access to the new therapies, which are mainly focused on substrate reduction for the oxalate-producing enzymes using RNA-interference.

Novel SCNN1A gene splicing-site mutation causing autosomal recessive pseudohypoaldosteronism type 1 (PHA1) in two Italian patients belonging to the same small town.

INTRODUCTION: Pseudohypoaldosteronism type 1 (PHA1) is a rare genetic disease due to the peripheral resistance to aldosterone. Its clinical spectrum includes neonatal salt loss syndrome with hyponatremia and hypochloraemia, hyperkalemia, metabolic acidosis and increased plasmatic levels of aldosterone. Two genetically distinct forms of disease, renal and systemic, have been described, showing a wide clinical expressivity. Mutations in the genes encoding for the subunits of the epithelial sodium channels (ENaC) are responsible for generalized PHA1. PATIENTS' PRESENTATION: We hereby report on two Italian patients with generalized PHA1, coming from the same small town in the center of Sicily. The first patient is a male child, born from the first pregnancy of healthy consanguineous Sicilian parents. A novel SCNN1A (sodium channel epithelial subunit alpha) gene mutation, inherited from both heterozygous parents, was identified by next generation sequencing (NGS) in the homozygous child (and later, also in the heterozygous maternal aunt). A more detailed family history disclosed a possible related twenty-year-old girl, belonging to the same Sicilian small town, with referred neonatal salt loss syndrome associated to hyperkalemia, and subsequent normal growth and neurodevelopment. This second patient had a PHA1 clinical diagnosis when she was about 1 year old. The genetic investigation was, then, extended to her and to her family, revealing the same mutation in the homozygous girl and in the heterozygous parents. CONCLUSIONS: The neonatologist should consider PHA1 diagnosis in newborns showing hyponatremia, hyperkalemia and metabolic acidosis, after the exclusion of a salting-loss form of adrenogenital syndrome. The increased plasmatic levels of aldosterone and aldosterone/renin ratio, associated to a poor response to steroid administration, confirmed the diagnosis in the first present patient. An accurate family history may be decisive to identify the clinical picture. A multidisciplinary approach and close follow-up evaluations are requested, in view of optimal management, adequate growth and development of patients. Next generation sequencing (NGS) techniques allowed the identification of the SCNN1A gene mutation either in both patients or in other heterozygous family members, enabling also primary prevention of disease. Our report may broaden the knowledge of the genetic and molecular bases of PHA1, improving its clinical characterization and providing useful indications for the treatment of patients. Clinical approach must be personalized, also in relation to long-term survival and potential multiorgan complications.

Autosomal recessive polycystic kidney disease: case report of a newborn with rare PKHD1 mutation, rapid renal enlargement and early fatal outcome.

INTRODUCTION: Autosomal recessive polycystic kidney disease (ARPKD; MIM#263200) is one of the most frequent pediatric renal cystic diseases, with an incidence of 1:20,000. It is caused by mutations of the PKHD1 gene, on chromosome 6p12. The clinical spectrum is highly variable, ranging from late-onset milder forms to severe perinatal manifestations. The management of newborns with severe pulmonary insufficiency is challenging, and causes of early death are sepsis or respiratory failure. In cases of massive renal enlargement, early bilateral nephrectomy and peritoneal dialysis may reduce infant mortality. However, there is no conclusive data on the role of surgery, and decision-making is driven by patient's clinical condition and expertise of the center. PATIENT PRESENTATION: We hereby describe a preterm female newborn with perinatal, rapid and bilateral, abnormal growth of both kidneys, respiratory failure and initial signs of liver disease. She was subsequently confirmed to be affected by a rare and severe homozygous mutation of the PKHD1 gene, inherited from both her consanguineous parents. Our patient died 78 days after birth, due to a fungal sepsis which worsened her respiratory insufficiency. CONCLUSIONS: This patient report shows some of the clinical and ethical issues of neonatal ARPKD, and the need of multidisciplinary approach and good communication with the family. Target next generation sequencing (NGS) techniques may guide and support clinicians, as well as guarantee to these patients the most appropriate clinical management, avoiding unnecessary and/or disproportionate treatments.

Renal angiomyolipomatosis and bleeding aneurysms in a tuberous sclerosis context: selective artery embolization in a girl with end-stage renal failure.

Recent developments in endovascular radiological techniques and devices have rendered embolization a major therapeutic option prior to surgery in many renal vascular or neoplastic diseases. A 19-yearold female patient, with a diagnosis of tuberous sclerosis complex (TSC) in childhood, was admitted with severe anemia. Polycystic kidney disease in end-stage renal failure appeared four years before and the patient has been undergoing peritoneal dialysis. The patient's medical history also included bilateral renal angiomyolipomas (AMLs). One year earlier, a unilateral endovascular embolization was performed to repair a bleeding aneurysm at the right renal upper pole. A second bilateral ruptured renal aneurysm was diagnosed at admission. To continue with peritoneal dialysis and prevent intrarenal hemorrhage and intraperitonal bleeding, an urgent bilateral renal AE was performed. Two months later she underwent a bilateral retroperitoneal nephrectomy. The posterior surgical approach, preserved the peritoneal surface area and adequate conditions to continue dialysis. At histology, bilateral AMLs were confirmed and a renal cell carcinoma of the right kidney was concurrently discovered. She undergoes continuous peritoneal dialysis. Urgent selective renal AE represents a feasible treatment for bilateral AML bleeding. It is safe and feasible before performing nephrectomy in patients with end-stage renal failure.

Fourier Transform Infrared Analysis of Urinary Calculi and Metabolic Studies in a Group of Sicilian Children.

INTRODUCTION: Prevalence of urinary calculi in children has been increasing in the past years. We performed an analysis of the chemical composition of stones formers of the pediatric population in our geographical area over the years 2005 to 2013. MATERIALS AND METHODS: Fourier transform infrared spectroscopy was employed for the determination of the calculus composition of a group of Sicilian children, and metabolic studies were performed to formulate the correct diagnosis and establish therapy. RESULTS: The prevalence of stone formation was much higher for boys than for girls, with a sex ratio of 1.9:1. The single most frequent component was found to be calcium oxalate monohydrate, and calcium oxalates (pure or mixed calculi) were the overall most frequent components. Calcium phosphates ranked 2nd for frequency, most often in mixed calculi, while urates ranked 3rd. The metabolic disorder most often associated with pure calcium oxalate monohydrate calculi was hypocitraturia, while hyperoxaluria was predominantly associated with calcium oxalate dihydrate calculi. CONCLUSIONS: Mixed calculi had the highest prevalence in our pediatric population. Our data showed that Fourier transform infrared spectroscopy was a useful tool for the determination of the calculi composition.

Mutational Spectrum of CYP24A1 Gene in a Cohort of Italian Patients with Idiopathic Infantile Hypercalcemia.

BACKGROUND/AIMS: Loss-of-function mutations in the CYP24A1 gene, which encodes the vitamin D-24 hydroxylase, have been recognized as a cause of elevated 1,25-dihydroxyvitamin D concentrations, hypercalcemia, hypercalciuria, nephrocalcinosis and nephrolithiasis in infants and adults. As only a case report describing 2 adult patients has been reported in Italian population, we report here the mutation analysis of CYP24A1 gene in an Italian cohort of 12 pediatric and adult patients with idiopathic infantile hypercalcemia (IIH). METHODS: We performed mutational screening of CYP24A1 gene in a cohort of 12 Italian patients: 8 children with nephrocalcinosis, hypercalcemia and PTH levels <10 pg/ml and 4 adult patients with nephrolithiasis, mild hypercalcemia and PTH levels <10 pg/ml from 11 unrelated Italian families. Clinical and biochemical data were collected. Genomic DNA was extracted from peripheral blood leucocytes using standard methods, and whole coding sequence of CYP24A1 gene was analysed in all patients and family members by polymerase chain reaction and direct sequencing. The potential pathogenicity of the newly identified missense mutations was evaluated by 3 different in silico approaches (Sorting Intolerant from Tolerant, Polyphen and Mutation Taster) and by comparative analysis in 14 different species using ClustalW software. RESULTS: CYP24A1 bi-allelic mutations were found in 8 individuals from 7 Italian families (7/11; 64%). Overall, 6 different CYP24A1 mutations, including one small deletion (p.Glu143del), 4 missense mutations (p.Leu148Pro; p.Arg396Trp; p.Pro503Leu; p.Glu383Gln) and one nonsense mutation (p.Tyr220*) were identified. Two out of 6 mutations (p.Tyr220* and p.Pro503Leu) were not previously described. Moreover, a new CYP24A1 variant was identified by genetic screening of asymptomatic controls. CONCLUSION: To the best of our knowledge, this is the first report of a CYP24A1 molecular analysis performed in an Italian cohort of adult and pediatric Italian patients. This study (1) confirms that CYP24A1 plays a causal role in some but not all cases of IIH (64%); (2) expands the spectrum of known CYP24A1 pathogenic mutations; (3) describes 2 hotspots detected in 50% of all Italian cases; and (4) emphasizes the importance of recognition and genetic diagnosis of CYP24A1 defects in infantile as well as adult hypercalcemia.

[Nephrocalcinosis in children].

Nephrocalcinosis (NC) is a renal disease characterized by deposition of calcium salts into the renal medulla. There are several causes, organic, iatrogenic, hereditary and sometimes related to extrarenal diseases. We studied 34 children affected by NC, 21 M and 13 F (average age at diagnosis 7.8 months), with the aim of analyzing the associated diseases, clinical manifestations, metabolic abnormalities, growth and renal function at onset and after follow-up. At onset 70% of patients were asymptomatic and diagnosis was occasional. Renal function was normal in 33 patients. The most frequent clinical symptoms were failure to thrive (9%), abdominal pain (6%), proteinuria/hematuria (7%). The associated diseases were: tubulopathies (8 pcs - tubular acidosis, Dent, Bartter and Lowe Syndromes), medullary sponge kidney, policalicosis (3 pcs ), Short bowel Syndrome (3 pcs), hyperparathyroidism, hypothyroidism (2 pcs), thalassemia (1pc), tyrosinemia (1 pc.). We recognized two forms of hypervitaminosis D. In a pc NC would be correlated with prematurity, another one with lipid necrosis. Among the metabolic abnormalities, observed in 25% of pcs, hyperoxaluria is the most frequent (47%), hypercalciuria (20%), hypercalcemia (15%). In some cases we found endocrine non pathogenic alterations: hypovitaminosis D (2 pcs) and hypoparathyroidism (6 pcs). During follow-up the growth was normal in 87% of cases and glomerular function was stable in 90% of pcs; IRC developed in 3 cases. From our analysis, it appears that the treatment of the underlying condition of NC is associated with catch-up growth and stabilization of renal function in most patients, but not with the reduction of the degree of the NC.

[Atypical Hemolytic Uremic Syndrome: experience of a pediatric center].

In the last two years we admitted in our Hospital 38 children with acute renal failure (ARF). Six of them were affected by hemolytic uremic syndrome (HUS) atypical. The aHUS is diagnosed in the presence of thrombotic microangiopathy (MAT), renal insufficiency (GFR 5%). The clinical presentation of our children has been varied and so also its evolution. Patients observed were all male, aged 2 to 12 years, and no one had a family history of kidney disease. In four patients we documented alterations of complement factors (MCP deficiency and factor H and presence of anti factor H). Repeated blood transfusions were required in 4 patients and in 3 patients the platelet count was slightly reduced. In 5 patients we did plasmapheresis and in 3 patients dialysis (hemodialysis and peritoneal dialysis). In three patients in whom the diagnosis was not clear, renal biopsy was performed to confirm the diagnosis. Eculizumab was administered in 3 patients resistant to plasma exchange. We obtain a rapid response on MAT with normalization of platelet count. The effect on renal function was variable (complete remission in a patient, partial improvement in another, and unresponsiveness in the last). The last had on Kidney biopsy signs of severe impairment and we documented the presence of antibodies to eculizumab. HUS is a rare condition, but probably much more common than reported. In children with ARF and microangiopathic anemia is necessary evaluated complement factors as early to obtain an improved clinical response to treatment with eculizumab.