Whole exome sequencing identified ATP6V1C2 as a novel candidate gene for recessive distal renal tubular acidosis.

Distal renal tubular acidosis is a rare renal tubular disorder characterized by hyperchloremic metabolic acidosis and impaired urinary acidification. Mutations in three genes (ATP6V0A4, ATP6V1B1 and SLC4A1) constitute a monogenic causation in 58-70% of familial cases of distal renal tubular acidosis. Recently, mutations in FOXI1 have been identified as an additional cause. Therefore, we hypothesized that further monogenic causes of distal renal tubular acidosis remain to be discovered. Panel sequencing and/or whole exome sequencing was performed in a cohort of 17 families with 19 affected individuals with pediatric onset distal renal tubular acidosis. A causative mutation was detected in one of the three "classical" known distal renal tubular acidosis genes in 10 of 17 families. The seven unsolved families were then subjected to candidate whole exome sequencing analysis. Potential disease causing mutations in three genes were detected: ATP6V1C2, which encodes another kidney specific subunit of the V-type proton ATPase (1 family); WDR72 (2 families), previously implicated in V-ATPase trafficking in cells; and SLC4A2 (1 family), a paralog of the known distal renal tubular acidosis gene SLC4A1. Two of these mutations were assessed for deleteriousness through functional studies. Yeast growth assays for ATP6V1C2 revealed loss-of-function for the patient mutation, strongly supporting ATP6V1C2 as a novel distal renal tubular acidosis gene. Thus, we provided a molecular diagnosis in a known distal renal tubular acidosis gene in 10 of 17 families (59%) with this disease, identified mutations in ATP6V1C2 as a novel human candidate gene, and provided further evidence for phenotypic expansion in WDR72 mutations from amelogenesis imperfecta to distal renal tubular acidosis.

Childhood Idiopathic Steroid Resistant Nephrotic Syndrome, Different Drugs And Outcome.

BACKGROUND: The management of steroid resistant nephrotic syndrome (SRNS) is quite difficult in paediatric patients. Not only the remission is difficult but also these patients are at risk of progression to end stage renal disease (ESRD). The goal of treatment is either to achieve complete remission or even partial remission as it is the most important predictor of disease outcome. METHODS: This study was conducted at The Children's Hospital, Lahore from February 2014 to May 2015. The SRNS patients of either sex between ages of 1-12 years were included with histology showing mesangioproliferative glomerulonephritis (MesangioPGN), focal segmental glomerulosclerosis (FSGS) or minimal change disease (MCD). Patients were given different immunosuppressant drugs and steroid 30 mg/m2 alternate day therapy on case to case basis and kept on regular follow up to check for response and adverse effects. RESULTS: Total of 105 patients included, 63 (60%) male and 42 (40%) female patients. The age ranges from 1.08 to 12 years, mean age of 6.53 years and SD of ±3.17. Tacrolimus was the most common drug used 43 (41%) patients followed by cyclosporine in 38 (36.2%) patients, while Mycophenolate mofetil (MMF) was prescribed in 21 (20%) patients. Complete response was in 96 (91.4%) initially while partial response was seen in 8 (7.6%) patients. On follow up, 92 (87.6%) patients showed complete response and partial response was in 5 (4.7%) patients. Cushingoid features and hypertrichosis were the most common adverse effect seen. CONCLUSIONS: Steroid resistant nephrotic syndrome can be managed well with various immunosuppressant drugs and steroids but treatment should be individualized according to clinical presentation, disease histology and cost/social factors.

TACROLIMUS DRUG LEVEL AND RESPONSE TO TREATMENT IN IDIOPATHIC CHILDHOOD STEROID RESISTANT NEPHROTIC SYNDROME.

BACKGROUND: The management of Steroid Resistant Nephrotic Syndrome (SRNS) is an uphill task for paediatric nephrologists as immunosuppressive agents are the mainstay of treatment in these patients. Tacrolimus is used along with steroids. This study is conducted to see the relationship between the tacrolimus dose, drug level and response in the management of SRNS. METHODS: This quasi experimental study was conducted at The Children's Hospital Lahore over a period of one year. Patients with SRNS of either sex and 1-10 years of age were included and those with secondary nephrotic syndrome were excluded. Tacrolimus was given at a dose of 0.05-0.1 mg/kg/day in 2 divided doses along with steroids. The follow-up was done for six months with proteinuria monitoring and tacrolimus drug levels done two weeks after initiation of treatment. RESULTS: Out of 42 patients, 27 (64.3%) were males and 15 (35.7%) were females. The most common histological diagnosis observed was mesangio-proliferative glomerulonephritis in 30 (71.4%) patients. The tacrolimus trough level range was 0.5-15.20 ng/ml with a mean value of 4.68 ng/ml ± 2.85. Forty-one (97.6%) children showed complete response to treatment while one patient showed partial response. CONCLUSION: This study suggests that tacrolimus is an effective drug for treatment of SRNS in paediatric patients and there is no linear relationship between the drug dose, response and drug level.

A rare case of Gitelman's syndrome with hypophosphatemia.

Gitelman's syndrome is a hereditary disorder occurring due to loss of functional mutations of the gene encoding the distal convoluted tubule sodium chloride cotransporter (NCCT) and is characterized by hypokalemic metabolic alkalosis, hypomagnesemia and hypocalciuria. This case reports an adolescent girl presenting with episodes of carpopedal spasms and difficulty in walking with laboratory tests suggestive of Gitelman's syndrome along with hypophosphatemia.

Galloway-Mowat syndrome.

Galloway-Mowat syndrome is a rare multisystem genetic disorder with constellation of neurological, skeletal, growth, facial, gastrointestinal and renal abnormalities. This case report describes Galloway-Mowat syndrome in a young boy suffering from congenital microcephaly, developmental delay, seizures and various dysmorphic features in whom nephrotic syndrome became apparent at 5 years of age.

Lupus nephritis in children.

OBJECTIVE: To determine the clinicopathological pattern of lupus nephritis in paediatric nephrology patients. DESIGN: Case series study. PLACE AND DURATION OF STUDY: The department of paediatric nephrology at the Children's Hospital and Institute of Child Health, Lahore, Pakistan, over a period of five years from January 2001 to December 2005. PATIENTS AND METHODS: Twenty six patients upto the age 16 years of either gender, with a mean age of 12.4 +/- 1.90 years having primary SLE with renal involvement in the form of oedema, hypertension, haematuria and proteinuria were included. Twenty one were females. Percutaneous renal biopsy was performed. Histological lesion was classified according to WHO classification. Patients were treated with immunosuppressive therapy and their clinical course was followed for at least one year. The mean duration of follow up was 1.77 years. RESULTS: Renal involvement was seen in 92.30% within 2 years of the onset of primary disease. Diffuse proliferative glomerulonephritis was the commonest histological lesion (n=14) followed by membranous nephropathy (n=6). The commonest clinical manifestation was oedema (80.76%) followed by hypertension (46.15%). Proteinuria was present in 100% of cases, haematuria in 38.46% and azotemia in 19.33% of patients. Nephrotic range proteinuria was more common in class III and IV, while azotemia was observed only in class IV. The disease was well controlled in 73.07% , relapse was seen in 3.8% of patients, 15.38% died of infections and uremic encephalopathy while 7.69% were lost to follow-up. CONCLUSION: Diffuse proliferative glomerulonephritis is the commonest histological lesion in our set-up. Renal involvement is mostly seen within first two years of the primary disease which can be controlled satisfactorily with immunosuppressive therapy.

Levamisole in steroid dependent and frequently relapsing nephrotic syndrome.

OBJECTIVE: To determine the efficacy of levamisole in steroid dependent (S.D) and frequently relapsing (F.R) nephrotic, from syndrome (N.S). DESIGN: Quasi-experimental study. PLACE AND DURATION OF STUDY: Department of Nephrology at The Children s Hospital, Lahore, over a period of 5 years from January 2000 to December 2004. MATERIAL AND METHODS: S.D.N.S and F.R.N.S patients between the ages of 1-15 years, were given levamisole on alternate day in a dose of 2.5 mg/kg, if either the dosage of steroids to maintain remission was >1 mg/kg/every other day (EOD), or 0.5 mg/kg/EOD with signs of steroid toxicity. The agent was continued for a period of one year and the steroids were gradually tapered off by 2.5-5 mg every four weeks to less than 0.5 mg/kg/EOD. The patients were monitored for maintenance of remission and side effects of drug. RESULTS: Seventy patients with a mean age of 5.50+/-2.97 years , with male to female ratio of 4:1 were studied. Nineteen (27.14%) patients did not relapse on therapy, while it was ineffective in 11(15.7%). Rest of 40 (57.14%) patients, though, relapsed during therapy, their duration of remission was prolonged from six months to one year, and dose of corticosteroids could be significantly reduced (0.1-0.3 mg/kg/EOD). It was also observed that levamisole is more effective in older children (>5 years versus <5 years) [P-value 0.03]. The only side effects were transient rash and occasional vomiting. CONCLUSION: Levamisole is a safe and effective steroid sparing drug, in steroid dependent and frequently relapsing nephrotic syndrome, for the prolongation of remission, especially in older children.

A familial hypomagnesemia--hypercalciuria (Manz syndrome).

We report a case of a rare inherited tubular disorder of linked transport of magnesium and calcium at the level of ascending limb of loop of Henle, characterized by hypomagnesemia, hypercalciuria and nephrocalcinosis, known as "Manz syndrome," who presented with polyuria, nystagmus and recurrent episodes of tetany with radiological evidence of rickets and nephrocalcinosis.

Comparison of Efficacy of Tacrolimus Versus Cyclosporine in Childhood Steroid-Resistant Nephrotic Syndrome.

OBJECTIVE: To compare the efficacy of tacrolimus versus cyclosporine (Calcineurin Inhibitors) in the management of childhood steroid-resistant nephritic syndrome (SRNS). STUDY DESIGN: Quasi-experimental study. PLACE AND DURATION OF STUDY: Department of Paediatric Nephrology at The Children's Hospital and Institute of Child Health, Lahore, from August 2014 to September 2015. METHODOLOGY: Patients of either gender aged 1 - 12 years, with the diagnosis of mesangioproliferative glomerulonephritis (MesangioPGN), focal segmental glomerulosclerosis (FSGS) or minimal-change disease (MCD) were included. Patients were assigned into two groups, one given tacrolimus in dose of 0.1 - 0.2 mg/kg/day in two divided doses, and other given cyclosporine in dose of 150 - 200 mg/m2/day in two divided doses along with oral steroids 30 mg/m2/day in divided doses, followed by alternate day with tapering dosage. Trough drug levels were done with dose adjustment accordingly. Patients were monitored and followed for the response to treatment and adverse effects of these two calcineurin inhibitors. RESULTS: Atotal of 84 patients, 58% males and 42% females, were included in the study. The age ranged from 1.25 to 12 years. The most common histopathological diagnosis was MesangioPGN (69.04%), FSGS (21.4%), and MCD (9.52%). Complete response was seen in 80.95% and 97.6% patients treated with cyclosporine and tacrolimus, respectively. Partial response was in 19.05% patients treated with cyclosporine and 2.4% in patients with tacrolimus. The most common adverse effect with cyclosporine and tacrolimus was hypertrichosis in 80.95% and 2.38%, hypertension 16.66% and 11.9% respectively while gum hypertrophy with cyclosporine was seen in 26.19% patients. CONCLUSION: Tacrolimus was more efficacious than cyclosporine in achieving remission in childhood SRNS with insignificant adverse effects.

Acute complications of haemodialysis in paediatric age group.

OBJECTIVE: To assess acute complications of haemodialysis in patients with end-stage renal disease (ESRD). DESIGN: Observational study. PLACE AND DURATION OF STUDY: The Nephrology Department of The Children's Hospital and Institute of Child Health, Lahore over a period of 2 years (January 2001-December 2002). PATIENTS AND METHODS: The children in age group of 6-14 years, suffering from end-stage renal disease (ESRD), were provided renal replacement therapy in the form of haemodialysis mostly twice a week and were observed for the complications of the procedure. RESULTS: A total 519 haemodialysis were performed on 25 patients. The mean age was 11.06 years and weight was 26.8 kg. The clinical problems observed were hypertension in 40.46%, hypotension 3.4%, chest pain 4.04%, headache 13.87%, vomiting 1.73%, gastrointestinal bleeding 1.92%, muscle cramps 8.6% and convulsions 0.57% of sessions. Hypokalemia was main electrolyte disturbance seen during 8%, while fever with rigors and chills in 4.02% of sessions. Minor bleeding from subclavian catheter was seen during 2.89% of sessions while thrombosis, infection and accidental dislodgment in 0.77%, 12.50% and 0.57% of sessions respectively. Technical problems like clotting in dialyzer during 0.95% and failure of ultra-violet control module was seen in 3.42% of sessions. CONCLUSION: Haemodialysis, a life saving treatment modality, is not without risk of complications. Hypertension, headache, muscle cramps and catheter infections were the most commonly encountered complications in this series.

Efficacy of steroids, cyclosporin and cyclophos-phamide in steroid resistant idiopathic nephrotic syndrome.

OBJECTIVE: To determine the efficacy of three different treatment protocols in steroid resistant idiopathic nephrotic syndrome, (SRINS). DESIGN: Interventional study. PLACE AND DURATION OF STUDY: Department of Nephrology at The Children's Hospital, Lahore, over a period of 3 years from January 2000 to December 2002. PATIENTS AND METHODS: Nephrotic children who did not respond to four weeks of steroid therapy (60mg/M2) followed by three pulses of methyl prednisolone (1Gm/1.73M2) over a period of one week were labeled as steroid resistant. Those with histopathological lesions of minimal change disease (MCD), focal segmental glomerulosclerosis (FSGS) and Mes.PGN were divided into 3 groups. Group-I was treated with cyclophosphamide (CPM) and oral steroids, group-II with cyclosporine and oral steroids and group-III with pulse methyl prednisolone (MPP) and oral steroid + CPM. The response to treatment and course of disease were observed in each group. RESULTS: Twenty patients with mean age of 4.4 years were enrolled. On the whole 10 (50%) had complete remission. In group-I, 5 (50%), in group-II, 3 (75%) and in group-III, 2 (33.3%) had complete remission. Depending upon histological lesion 100% (n=2) with MCD, 50% (n=6) with Mes.PGN and 25% (n=1) with FSGS achieved complete remission. Cyclosporine and CPM induced remission in 100% of patients with MCD, while in Mes.PGN response rate in group-I, II, and III was 100% (n=1), 50%(n=1), and 44.4%(n=4) respectively. In patients with FSGS, MPP was the only drug used with limited response of 25% (n=1). CONCLUSION: Cyclosporine proved to be a better option for MCD and Mes.PGN, while MPP showed limited response in patients with FSGS.

Nephronophthisis: a variant.

The case report describes a young boy with renal, retinal, hepatic and cerebellar involvement in a rare syndrome. He had polyuria, deranged renal functions and cystic lesions in kidneys, which led to the diagnosis of nephronophthisis (NPH). Extra-renal involvement with night blindness, truncal ataxia, mental retardation and hepatosplenomegaly. Thus, every patient with NPH should be carefully examined for extra-renal involvement.

A spectrum of novel NPHS1 and NPHS2 gene mutations in pediatric nephrotic syndrome patients from Pakistan.

BACKGROUND: Mutations in the NPHS1 and NPHS2 genes are among the main causes of early-onset and familial steroid resistant nephrotic syndrome respectively. This study was carried out to assess the frequencies of mutations in these two genes in a cohort of Pakistani pediatric NS patients. METHODS: Mutation analysis was carried out by direct sequencing of the NPHS1 and NPHS2 genes in 145 nephrotic syndrome (NS) patients. This cohort included 36 samples of congenital or infantile onset NS cases and 39 samples of familial cases obtained from 30 families. RESULTS: A total of 7 homozygous (6 novel) mutations were found in the NPHS1 gene and 4 homozygous mutations in the NPHS2 gene. All mutations in the NPHS1 gene were found in the early onset cases. Of these, one patient has a family history of NS. Homozygous p.R229Q mutation in the NPHS2 gene was found in two children with childhood-onset NS. CONCLUSIONS: Our results show a low prevalence of disease causing mutations in the NPHS1 (22% early onset, 5.5% overall) and NPHS2 (3.3% early onset and 3.4% overall) genes in the Pakistani NS children as compared to the European populations. In contrast to the high frequency of the NPHS2 gene mutations reported for familial SRNS in Europe, no mutation was found in the familial Pakistani cases. To our knowledge, this is the first comprehensive screening of the NPHS1 and NPHS2 gene mutations in sporadic and familial NS cases from South Asia.