Genetic background of pediatric PAH in Spain and its clinical implications: data from the REHIPED Spanish Registry

Background

The genetic background of pulmonary arterial hypertension (PAH) in the Spanish pediatric population could be different from the genetic background described in other countries. Besides, clinical implications of a positive genetic result in the PAH pediatric population are not fully understood yet, and could result in the “reclassification” of patients from one PAH group to another type among the current pediatric classification.

Material and methods

Patients under 19 years at diagnosis included in the REHIPED registry from January 2011 to December 2021 were included. Clinical variables and genetical results were recorded. Succesive NGS panels involving up to 35 genes were used. After the results of the genetic testing, we analyzed differences in survival, and if patients “moved” to another category in the current Nice classification.

Results

In the selected cohort of 98 patients (56.1% female), median age at diagnosis was 7.1 years (IQr 1.5–14.7), and ethnicity as follows: Caucasian (81.6%), Romani (8.2%), others (10.2%) (Table 1). Before the genetic testing, patients had been classified as Idiopathic (53.1%), Congenital Heart Disease-PAH (30.6%), Heritable (5.1%), Pulmonary veno-oclusive disease (PVOD) 6.1%, and Multisystemic disorder associated with PAH (5.1%). Pathogenic or likely pathogenic variants were found in 44 of the screened patients (44.9%): BMPR2 (12 cases), EIF2AK4 (9), TBX4 (n=4), MECP2 (n=3), KCNK3 (n=2), FOXF1 (n=2), NFU1 (N=4), ACVRL1 (n=1), BMPR1B (n=1), CLBCI (n=1), GBE1 (n=1), GDF2 (n=1), SOX17 (n=1), VHL (n=1), and digenic pathogenic variant in ABCC8/SMAD1 (n=1). After genetic analysis, 28 patients (28.6%) were “reclassified” (Fig. 1, panel A), with HPAH, PVOD and multisystemic disorders increasing up to 18.4%, 8.2%, and 12.2%, respectively. Worse Survival from death or lung transplantation was observed in heritable PVOD and multisystemic disorders (Fig. 1, panel B).

Conclusions

The Spanish pediatric PAH population showed higher prevalence of EIF2AK4 than other pediatric registries. Genetic testing resulted in the “reclassification” of a significant number of patients.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Rio Hortega grant from the Spanish Ministry of Science and Innovation (Instituto de Salud Carlos III).

Novel genetic and molecular pathways in pulmonary arterial hypertension associated with connective tissue disease

Introduction

PAH is a severe complication of CTD, with remarkable morbidity and mortality. SSc is most commonly associated with PAH, but it can be present in other CTD. Despite major advances in PAH therapy, survival in CTD-PAH remains poor. Furthermore, the molecular and genetic basis of PAH in CTD are not well established.

Purpose

This study aimed to screen for genetic defects in a cohort of patients with CTD-PAH.

Methods

Since November 2011, genetic testing is offered to all patients with idiopathic, hereditable and associated forms of PAH, and PVOD included in a national registry of PAH. A PAH-specific panel of 35 genes was designed.

Results

During enrolling, 79 patients were recruited: 59 SSc, 11 SLE and 9 other. 69 female, mean age 55,6±1,9 years, mean PVR 8,6±0,5 WU and mean DLCO 47,5±2%. Disease-associated variants were observed in 9 patients: 4 pathogenic/likely pathogenic in 4 different genes (TBX4, ABCC8, KCNA5 and GDF2/BMP9) and 5 VUS in 4 genes (ABCC8, NOTCH3, TOPBP1 and CTCFL). Clinical characteristics of patients with pathogenic/likely pathogenic variants and variant analyses are shown in Tables 1 and 2.

Patient 1 is a Caucasian female with mixed CTD, diagnosed with PAH at 58 years of age. She has a frameshift pathogenic variant in TBX4. Pulmonary function test (PFT) ruled out interstitial lung disease (ILD), but a reduction in DLCO was observed (61% of predicted).

Two patients carry variants in ABCC8. Patient 2 is a Caucasian female with SSc, diagnosed with PAH at 27 years of age. She carries a splicing variant in ABCC8, classified as likely pathogenic. Her mother was diagnosed with PAH associated with a repaired ASD at 61 years of age. In the genetic testing, no variants were observed in PAH genes. DLCO was 71% of predicted, without signs of ILD. Patient 3 is a Caucasian male, with clinical suspicion of PVOD associated with SSc and HIV infection. PAH was diagnosed at 57 years of age. He presented a missense variant in ABCC8, located in a gating regulatory region, and classified as VUS. Her sister was also diagnosed with PVOD associated with SSc at 48 years of age. No blood or tissue samples are available. In patient 3, DLCO was 22% of predicted value. CT scan showed the typical triad of PVOD.

Patient 4 is a Latin American female with SLE, diagnosed with PAH at 25 years of age. She presented a pathogenic nonsense variant in GDF2/BMP9.

Patient 5 is a Caucasian female with SSc, diagnosed with PAH at 70 years of age. She presented a pathogenic variant in KCNA5.

Patients 6–9 have SSc-PAH and carry VUS in NOTCH1, CTCFL, CTCFL and TOPBP1, respectively.

Conclusions

We demonstrate the practical diagnostic utility of genetic testing with a panel in CTD-PAH. The discovery of rare variants in these patients forces us to take a comprehensive approach and accurate genetic counseling. Further research is still necessary to confirm these findings and help to provide a personalized medicine approach to these patients.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): This project was founded by project “Bases Genético Moleculares de la Medicina de Precisiόn en la Hipertensiόn Arterial Pulmonar”. Funder: Instituto Carlos III. Ministerio de Economía y Competitividad.

BMPR2 variants in pulmonary arterial hypertension. Are they really worrisome?

Background

Pulmonary arterial hypertension (PAH) is a rare and severe disease. The discovery of the gene encoding Bone Morphogenetic Protein Receptor Type 2 (BMPR2) in 2000 was the first evidence of an association between genetics and PAH. BMPR2 mutation carriers are younger and have higher haemodynamic severity, determining higher risk than sporadic cases. In the last few years, novel genetic variants have been identified. The risk of mortality of the currently known mutations is scarce.

Purpose

To describe the role of gene variants regarding long-term survival in a cohort of PAH patients.

Methods

We included patients diagnosed with PAH between January 2011-December 2020, following the ESC/ERC Guidelines recommendations. At least one genetic study was available in included individuals. Pulmonary venooclusive disease, PAH associated with congenital heart disease, or connective tissue disorders were excluded. Three groups were compared: no mutation, BMPR2 carriers and other genetic variants. Comparison of qualitative and quantitative variables was done by Chi-square test and ANOVA test, respectively. Crude and adjusted Log-rank test was performed for the evaluation of mortality.

Results

361 were finally included. The most frequent gene variant was BMPR2. Among the eight other gene variants, there were 2 cases of KCKN3, 2 of ACVRL1, and 1 case of KCNA5, TBX4, CPS1, and GDF2.

BMPR2 and the rest of mutation carriers were younger at diagnosis and had worse haemodynamic parameters than non-carriers. Nevertheless, these patients tended to perform higher distances in the 6-minute walk test. Interestingly, BMPR2 patients had higher DLCO values at diagnosis (table).

After 104.1±77.2 months of follow-up, there was a tendency for BMPR2 carriers toward lower crude free survival of mortality or lung transplantation. Nevertheless, this survival benefit disappears when adjusted by age (Table, figure).

Conclusions

The diagnostic yields of genetic analysis for pathogenic or likely pathogenic variants in idiopathic PAH are approximately 11%. BMPR2 is the most frequent causal gene. These patients are associated with marked haemodynamic impairment. Nevertheless, its younger age probably determines the better long-term results regarding mortality or lung transplantation observed when comparing these results with sporadic patients or those carrying other mutations.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Rio Hortega grant. Instituto de Salud Carlos III (ISCIII), Ministry of Science and Innovation, Spanish Government.

Genetic background in pediatric pulmonary arterial hypertension. Should we change the current recommendations for genetic testing?

Background

Pulmonary arterial hypertension (PAH) is a rare and severe disease, genetically predisposed in a high proportion of patients. PAH is subclassified in different subtypes depending on the underlying condition. Gene variants are more frequent among heritable or idiopathic forms. Nevertheless, pathogenic variants have been described across the entire spectrum of this disease. Evidence regarding genetics in pediatric PAH is scarce [1].

Purpose

Our aim is to describe the prevalence of significant gene mutations among a pediatric PAH cohort and to define specific data in the different subtypes.

Methods

Samples for genetic studies were obtained from blood tests of patients included in the Spanish National Registry of Pediatric Pulmonary Hypertension (REHIPED). Guardians signed informed consent before the inclusion in the study. Qualitative variables were compared by Chi-square test. Quantitative variables were assessed by Kruskal-Wallis, considering the asymmetric distribution of variables. STATA 14.0 was used for analyses.

Results

Sixty four patients were included between 2011 and 2021. Median age of the entire sample was 7.1 years (2.0–12.6) and 42.2% of them were male. There were significant differences in the age at diagnosis and race between the different included groups (table). Pathogenic or likely pathogenic variants were more frequent in familial pulmonary venooclusive disease (PVOD) and familial PAH cases. A similar percentage of mutations were found in idiopathic cases and in PAH associated with congenital heart disease (Figure). Gene variants in the gene encoding the bone morphogenetic protein receptor type 2 (BMPR2) were the most frequent mutations in the PAH familial cohort and there was also the most frequent finding in congenital heart disease and sporadic PAH, in conjunction with the TBX4 gene. Homozygous or compound heterozygous EIF2AK4 (eukaryotic translation initiation factor 2 a kinase 4) mutations were found in all the patients diagnosed with PVOD. Heritable PAH and PVOD cases were diagnosed more frequently after family screening.

Conclusions

This study shows a comparable proportion of pathogenic-likely pathogenic gene mutations in patients diagnosed of pulmonary arterial hypertension associated with congenital heart disease and idiopathic cases, with similar distribution of specific genes. BMPR2 and TBX 4 were the most frequent gene variants in this pediatric PAH population. BMPR2 and EIF2AK4 are the most common mutations in familial PAH and PVOD subtypes, respectively.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): ACU holds a Rio Hortega Grant from the Instituto de Salud Carlos III, Spanish Ministry of Science and Innovation.JAT and NG hold grants from FEDER (Federaciόn Española de Enfermedades Raras) and from the FCHP. Table 1. Characteristics of PAH subtypesFigure 1. PAH and ACMG classification.

Strong association of socioeconomic status with genetic ancestry in Latinos: implications for admixture studies of type 2 diabetes

AIMS/HYPOTHESIS

Type 2 diabetes is more prevalent in US American minority populations of African or Native American descent than it is in European Americans. However, the proportion of this epidemiological difference that can be ascribed to genetic or environmental factors is unknown. To determine whether genetic ancestry is correlated with diabetes risk in Latinos, we estimated the proportion of European ancestry in case-control samples from Mexico and Colombia in whom socioeconomic status had been carefully ascertained.

METHODS

We genotyped 67 ancestry-informative markers in 499 participants with type 2 diabetes and 197 controls from Medellín (Colombia), as well as in 163 participants with type 2 diabetes and 72 controls from central Mexico. Each participant was assigned a socioeconomic status scale via various measures.

RESULTS

Although European ancestry was associated with lower diabetes risk in Mexicans (OR [95% CI] 0.06 [0.02-0.21], p = 2.0 x 10(-5)) and Colombians (OR 0.26 [0.08-0.78], p = 0.02), adjustment for socioeconomic status eliminated the association in the Colombian sample (OR 0.64 [0.19-2.12], p = 0.46) and significantly attenuated it in the Mexican sample (OR 0.17 [0.04-0.71], p = 0.02). Adjustment for BMI did not change the results.

CONCLUSIONS/INTERPRETATION

The proportion of non-European ancestry is associated with both type 2 diabetes and lower socioeconomic status in admixed Latino populations from North and South America. We conclude that ancestry-directed search for genetic markers associated with type 2 diabetes in Latinos may benefit from information involving social factors, as these factors have a quantitatively important effect on type 2 diabetes risk relative to ancestry effects.

[Chronic renal failure secondary to hyperoxaluria following small bowel syndrome]

A 70-year-old woman was admitted in the Department of Nephrology because of renal insufficiency. Six years previously, as consequence of a venous mesenteric thrombosis, she underwent an extense intestinal resection with subsequent short intestine syndrome. Five years after the surgery an increase in the creatinine concentration was observed (1.4 mg/dl). One year later, it increased up to 3.1 mg/dl and the patient was remitted to our Department. The radiological study revealed calcifications on both kidney silhouettes. In the next year, renal function worsened and the calcifications increased. Coinciding with the beginning of the chronic hemodialysis treatment she suffered a renal colic with passage of a calcium oxalate stone.

Influence of cyclosporin A (CyA) on renal handling of urate

Hyperuricaemia is a frequent side-effect of cyclosporin A (CyA) therapy in renal transplant patients, and gout arthritis is the cause of considerable morbidity among these patients. However, neither the potential predisposing factors nor the mechanisms of hyperuricaemia have been clearly elucidated. It has been reported that hyperuricaemia in patients on CyA is associated with a lowered glomerular filtration rate, or with a reduced urate clearance, due to an increase in the net tubular urate reabsorption or to a decrease in secretion. These conclusions are mostly supported by measurements of the basal clearance rate and fractional excretion of urate, but more precise studies of renal handling of urate by the renal tubule have seldom been performed. The purpose of our study was to investigate the prevalence of hyperuricaemia in our population of renal transplant patients, as well as the risk factors involved. Furthermore, we have evaluated the mechanism of hyperuricaemia by a combined pyrazinamide and probenecid test allowing a better evaluation of urate transport processes than pyrazinamide alone.

Renovascular hypertension in children

OBJECTIVE

To study the etiology, clinical spectrum. image findings, management and outcome of children with renovascular hypertension (RVH).

MATERIAL AND METHODS

Twenty children (aged 5 days to 15 years) were studied and treated for RVH during 1977-1998. In 14 cases hypertension was found during a routine examination. Six cases had heart failure and/or hypertensive encephalopathy. Diagnosis was made with aortography. Post-captopril renography and Doppler ultrasonography were obtained in 8 patients and spiral computed tomography angiography in 2. Treatment consisted of surgery (8 patients), percutaneous transluminal angioplasty (PTA) (5) or antihypertensive drugs only (8).

RESULTS

Initial blood pressure was 62 +/- 31 mmHg > 95th percentile for systolic and 44 +/- 22 mmHg for diastolic blood pressure. Twelve children had unilateral and 8 had bilateral arterial stenosis. In 3 cases lesions were intrarenal. RVH was due to fibromuscular dysplasia (7 patients) and associated to middle aortic syndrome (5). neurofibromatosis (3), William's syndrome (2). Takayasu's arteritis (1) and pheochromocytoma (1). Treatment of choice was decided depending on the size of the child and location and severity of the stenosis. At the end of the follow-up (78 +/- 49 months), 9 patients are normotensive without medication and 7 are normotensive with drugs. Three patients have died, 2 for unrelated causes and I for cardiac failure; 1 child was lost to the follow-up.

CONCLUSIONS

Although symptoms are relatively uncommon. renovascular disease is a frequent cause of severe hypertension in childhood. Non-invasive diagnostic techniques appear useful as screening methods. Treatment by surgery or PTA is successful if patients are carefully selected.

[Long-term prognosis of childhood IgA nephropathy in adult life]

BACKGROUND

To evaluate long-term prognosis in a group of children with IgA nephropathy and to analyse which clinical factors were associated with progression to chronic renal failure in adulthood.

PATIENTS AND METHOD

Retrospective study. 58 young adults with IgA nephropathy diagnosed at 10.6(SD 2.9) years old and studied after a follow-up of 11.8 (SD 2.9) years.

RESULTS

Relapses of macroscopic hematuria and proteinuria were the most frequent symptoms at onset (75.9%). In 25.9% of patients high plasmatic IgA levels were also detected. Most cases had grade I (44.8%)or grade II (44.8%) histological lesions at diagnosis. At the last control, clinical remision was observed in 21 patients (36.2%) and 50% of the whole group remained with abnormal urine. 8 patients(13.8%) reached terminal renal failure. Mean renal survival (defined as glomerular filtration rate above 50 ml/min/1.73 m2)was 100, 93.3 and 81.1% at 5, 10 and 15 years of evolution, respectively.

CONCLUSIONS

About 14% of children with IgA nephropathy had long-term renal bad prognosis. Hypertension at onset, plasma creatinine elevation and proteinuria during adolescence were significant risk factors associated with chronic renal failure during adulthood. Minimal lesions at IgA nephropathy diagnosis in children did not exclude long-term poor prognosis.

Prognosis of patients with acute renal failure without cardiopathy

BACKGROUND

The outcome for children with acute renal failure (ARF) may be poor. However, relatively few published studies have considered prognosis of these patients.

METHODS

We prospectively studied, from 1978 to 1998, 92 such children without heart disease to try to identify risk factors for mortality.

RESULTS

Forty five per cent of children with tumours, shock, and other causes died compared with none of those with a primary urinary tract related problem. ARF did not seem to be the cause of death in any case. Univariate analysis showed that in the non-primary urinary problem group (55 cases), patients with hypotension, high values of BUN or creatinine, or who needed mechanical ventilation or dialysis, had a poor outcome. Multivariate analysis showed that probability of death can be estimated using the following score: -0.02 + 0.28 (hypotension) + 0.19 (ventilation) + 0.27 (dialysis) + 0.01 (BUN).

CONCLUSIONS

Mortality of patients with ARF was related to aetiology, the need for dialysis and/or ventilator use, hypotension, and BUN values.

Tubulointerstitial nephritis and asymptomatic uveitis

We describe a case of a 10 year-old boy who had fever, weakness, anorexia, weight loss and general malaise. No other remarkable symptoms were present. He had been treated with Aspirin and Ibuprofen. Deterioration of renal function, glucosuria, proteinuria, anemia and increased erythrocyte sedimentation rate were detected. After 7 days observation with no treatment, renal function worsened, glucosuria increased and fever persisted. A renal biopsy was performed and acute tubulointerstitial nephritis was diagnosed. The most common aetiologies of this entity were excluded. An ophthalmologic study revealed bilateral anterior uveitis, therefore the patient was diagnosed as having tubulointerstitial nephritis with uveitis. The child improved on corticosteroid therapy, but uveitis relapsed when treatment was stopped.

Nephrogenic diabetes insipidus and renal tubular acidosis secondary to foscarnet therapy

Foscarnet is used as therapy of cytomegalovirus (CMV) infection in immunosuppressed subjects. We present a patient with human immunodeficiency virus infection under treatment with foscarnet for CMV retinitis who complained of thirst and polyuria. Laboratory data showed hypernatremia with increased plasma osmolality and metabolic hyperchloremic acidosis. A water deprivation test demonstrated a nephrogenic diabetes insipidus. Other laboratory studies, including urine pH, anion gap, titratable acidity, and bicarbonate, showed a distal tubular acidification defect. All abnormalities were transient, with recovery a few days after foscarnet withdrawal. No cases of renal acidosis, and only one case of nephrogenic diabetes insipidus, has been previously reported as a complication of foscarnet treatment. Our patient developed both nephrogenic diabetes insipidus and renal tubular acidosis with a temporal pattern that demonstrated a link between foscarnet therapy and these abnormalities.

Impairment of tubular secretion of urate in renal transplant patients on cyclosporine

The prevalence of hyperuricemia was investigated in 214 kidney allograft recipients, 81 were on azathioprine and steroids and 133 on cyclosprine (CyA) and low-dose steroids or on triple therapy. All had stable renal function, serum creatinine < 2.5 mg/dl, and a follow-up between 12 and 120 months. At the time of the study, blood and urine samples were obtained to perform tests of renal function. The renal handling of urate was evaluated by a combined pyrazinamide and probenecid test in 35 selected patients (12 normouricemic on azathioprine, 9 normouricemic on CyA and 14 hyperuricemic on CyA). The prevalence of hyperuricemia was higher in the group of patients on CyA (19.7 vs. 66.9%, p < 0.001), as well as the concentration of serum urate (6.1 +/- 1.9 vs. 7.6 +/- 1.7, p < 0.001), and serum creatinine (1.2 +/- 0.3 vs. 1.4 +/- 0.4, p < 0.001). In patients on CyA, multivariate analysis showed that the most important predictive variables of hyperuricemia were: serum creatinine, FEurate, diuretic use and CyA blood levels (r = 0.73, p < 0.0001). Thirteen patients on CyA (9.9%) had at least one episode of gouty arthritis. Those patients were older than the hyperuricemic patients without gout (45.7 +/- 6.7 vs. 37.1 +/- 13.5 years, p < 0.01), had worse renal function (serum creatinine 1.9 +/- 0.4 vs. 1.5 +/- 0.4 mg/dl, p < 0.01), and higher prevalence of hypertension (100 vs. 63.1%, p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Progression of renal failure in chronic primary glomerular diseases

The rate of progression of renal failure was analyzed in 19 patients with biopsy-proven chronic primary glomerular diseases, by the slope (regression coefficient) of the linear regression of reciprocal serum creatinine on time. The relative importance of proteinuria, sex, underlying disease and components of arterial pressure (systolic, diastolic and mean) was tested using stepwise multiple linear regression, the dependent variable being the slope of progression. We found that the only variable significantly related with slopes of progression was arterial pressure. Hypertension was found in 14 of the 19 patients. There was a significant linear relationship (p < 0.05) between mean arterial pressure and slopes of progression. Notwithstanding, the best fit to the data follows a quadratic function (p < 0.001 for mean arterial pressure), which corresponds to a negative parabolic curve. Therefore, either low or high values of mean arterial pressure were associated with faster mean progression rates. Thus, an accurate approach of this relationship fits a nonlinear regression model.

Prognosis of children with acute renal failure: a study of 138 cases

Acute renal failure (ARF) in children has a poor prognosis in spite of modern therapeutic techniques. For this reason, it would be useful to have prognostic indicators early in the course of the disease, in order to identify those patients that could benefit most from aggressive treatment. In an attempt to establish valid prognostic factors, we prospectively studied 138 cases of ARF in children. We examined age, sex, etiology of ARF, previous surgery, prerenal origin, clinical situation of the patient when first seen by the nephrologist and complications. All these variables were statistically analyzed individually by univariate tests and, except for sex and complications, also by multiple regression analysis. Median age of the patients was 26 months. The etiology of ARF was nephropathy in 16, tumor in 14, cardiopathy in 85 and other causes in 23 cases. For analysis, patients were divided into patients with and without prerenal ARF. In the prerenal group, mortality-related factors were hypotension, need for ventilatory support, age less than 1 month and serum values of creatinine. In the nonprerenal ARF group, the need for assisted ventilation and the need for dialysis correlate positively with the mortality, while an exclusive nephrological etiology was associated with less probability of death.

Prognosis of acute tubular necrosis: an extended prospectively contrasted study

The ability to predict the outcome in acute tubular necrosis (ATN) remains elusive despite considerable efforts. Accurate prediction is a crucial priority and has large economical and ethical implications, mainly to judge when treatment is futile and further efforts only prolong miserable agony. To analyze the influence of risk factors in the prognosis of ATN, we applied, in an initial phase, a prospective protocol of demographic data, cause of renal failure, diuresis, need of dialysis and clinical conditions in 228 patients using multiple linear and logistic regression models. In a control phase with 100 consecutive patients, we checked the accuracy of the results previously obtained, evaluating further the overall population of 328 patients in a synthetic phase. Finally, the validation of the equations obtained was verified in 25 patients from another hospital. As a complement of this 4-phase study, detailed statistical comparisons between both linear and logistic multiple regression models were undertaken. Correlation between probability of death obtained with equations from the initial phase applied to control patients and real evolution of these patients, survival or death, was excellent. The study of the synthetic phase revealed coma, assisted respiration, hypotension, oliguria and jaundice as having an independent positive influence on mortality and nephrotoxic etiology and normal consciousness on good prognosis. For the linear model, the same cut-off point of discriminant score (0.9) above which there were no chances for survival could be established in the 4 phases. With the logistic model, it only was found at later phases. The multiple linear was better than the logistic regression model in terms of better correlation with real mortality, better sensitivity and specificity intervals, easier use of discriminant cut-off point and better adjustment of distribution of standardized residuals to expected normal function. Early prognosis of ATN is possible and can be given using simple clinical features. A discriminant score allows to distinguish patients without chances for survival. The multiple linear is better than the logistic regression model in the prediction of the outcome in ATN.

Urinary acidification response to furosemide administration in patients on low-dose cyclosporine therapy

The response of urinary acidification parameters and electrolytes to furosemide administration was prospectively studied in 9 psoriatic patients treated with a low-dose cyclosporine A schedule (initial dose: 5 mg/kg body weight) before beginning cyclosporine A, after 3 months on cyclosporine A and 1 month after cyclosporine A withdrawal. The test was also performed in 29 psoriatic patients after 3 months on 5 mg/kg body weight cyclosporine A treatment. There were no significant differences between before and after cyclosporine A treatment regarding furosemide-induced changes in urinary volume, sodium or potassium excretion. Contrarily, the post-furosemide urinary pH decrease and ammonium and titrable acid increase were significantly lower in cyclosporine-A-treated patients. Five of the 29 studied patients showed abnormal furosemide tests (17%). These patients had lower total serum CO2, urea and creatinine but similar serum potassium and fractional potassium excretion. We conclude that some patients treated with low-dose cyclosporine A therapy develop an abnormal tubular distal response to furosemide administration, suggesting an alteration in the H(+)-ATPase pump or a voltage-dependent mechanism.

Subclinical impairment of distal renal acidification induced by low-dose cyclosporin A therapy

Twenty-nine psoriasis patients on 5 mg/kg cyclosporin A (CyA) therapy were studied for 3 months using the furosemide test. Five of them (17%) showed an abnormal renal acidification capacity after furosemide administration: The urinary pH did not sink under 5.3 after furosemide, while the ammonium and titrable acid levels were significantly low. There were no significant differences from controls regarding the serum potassium or fractional potassium excretion. Nevertheless, the transtubular potassium gradient was lower in patients with an abnormal furosemide test result. We conclude that some patients treated with a low dose CyA therapy developed an abnormality in the distal tubular acidification.

[Treatment of homozygotic familial hypercholesterolemia with continuous apheresis of low density lipoproteins]

A boy of 8 years 4 months of age was diagnosed as having homozygotic familial hypercholesterolemia and commenced treatment with an apheresis technique of low density lipoproteins. This procedure consists in the extracorporeal elimination of low density lipoproteins by fixing the same in a cellulose column with dextran-sulphate. Each session lasts between 90-150 minutes and is carried out weekly. Prior to initiation of the treatment, the total plasmatic concentration of cholesterol was 24 mml/l (930 mg/dl), low density lipoprotein ligated cholesterol 22.6 mmol/l (876 mg/dl) and high density lipoprotein ligated cholesterol 0.98 mmol/l (38 mg/dl). Following 8 weeks of treatment total cholesterol and low density lipoprotein ligated cholesterol were 10 mmol/l (394 mg/dl) and 8.6 mmol/l (335 mg/dl) respectively upon commencing the treatment and 4.7 mmol/l (184 mg/dl) and 3 mmol/l (118 mg/dl) upon completion of the same. This is the first time in Spain that treatment with this technique has been used in homozygotic familial hypercholesterolemia.

Acute interstitial nephritis superimposed on glomerulonephritis: report of a case

A 7-year-old boy with a history of recurrent acute renal failure and macroscopic haematuria is reported. A renal biopsy performed during the first episode of renal function deterioration showed mesangial glomerulonephritis with C3 mesangial deposits. Macroscopic haematuria associated with respiratory infections recurred four times over the next 14 months, each time in association with acute derangement of renal function. A second biopsy showed acute interstitial nephritis and similar glomerular abnormalities. Retrospectively, a causal relationship between the ingestion of paracetamol and the appearance of the symptoms was observed. No derangement of renal function was present in subsequent episodes of macroscopic haematuria following removal of the offending drug. This is a case of drug-induced acute interstitial nephritis superimposed on a glomerular disease, and suggests the importance of recognizing this association.

Clinical significance of IgM mesangial deposits in the nephrotic syndrome

We have studied 32 patients with idiopathic nephrotic syndrome aged from 3 to 59 years. The clinical course of 20 patients with IgM mesangial deposits was compared with that of 12 patients without glomerular immune deposits. The presence of IgM deposits seems to be unrelated to any particular clinical onset, histological pattern on light microscopy, therapy response, or clinical course in our relatively short follow-up. The conclusion from this study is that IgM mesangial deposition is not a marker for response to therapy in patients with idiopathic nephrotic syndrome.

Mesangial deposits of IgM in patients with the nephrotic syndrome

Kidney biopsies from fourteen patients with the nephrotic syndrome were studied by light, immunofluorescence and electron microscopy. Morphologically, all cases showed moderate diffuse mesangial cell proliferation. In all cases, immunofluorescent microscopy demonstrated diffuse and generalized deposits of IgM as the sole or predominant immunoglobulin. Electron microscopic examination showed electron dense deposits localized in the mesangium in seven cases. One nephrotic patient experienced spontaneous remission and eight others were steroid responsive. Only one of the five steroid resistant patients treated with chlorambucil showed clinical remission. Five steroid responsive patients relapsed. At present, four patients are healthy, having not relapsed for the past two years. Although deposits of IgM may be related to the renal pathology in cases of the nephrotic syndrome, immunofluorescence findings do not seem to be sufficiently consistent or characteristic to justify a possible subclassification of the idiopathic nephrotic syndrome.

Familial C1q deficiency in 3 siblings with glomerulonephritis and Rothmund-Thomson syndrome

Complete absence of C1q was demonstrated in the sera of 3 siblings in association with renal and cutaneous lesions. The serologic findings were consistent with an autoimmune disorder. Hematuria was the renal symptom present in all 3 patients; proteinuria was also present in 1. Renal biopsies showed mesangial proliferative glomerulonephritis with diffuse glomerular deposits of IgM and C3 in all cases. Clinical cutaneous manifestations and the histological picture were those of the Rothmund-Thompson syndrome. Three combined diseases, characterized by renal and cutaneous affection and serologic abnormalities, are presented in this paper.