We report the case of an 8-year-old girl diagnosed with atypical hemolytic uremic syndrome (aHUS) with a complement factor B (CFB) gene mutation. aHUS is a disease of complement dysregulation. In approximately 50% of patients, mutations are identified in genes encoding regulators of complement-complement factor H (CFH), membrane cofactor protein or complement factor I (CFI)-or activators of complement-complement factor B (CFB) or C3. The mutation in this patient was identified in exon 12 of CFB and changes a lysine at amino acid position 533 to an arginine (c.1598A>G p.Lys533Arg). The two other mutations previously reported in CFB associated with aHUS are c.858C>G, p.F286L in exon 6 and c.967A>Gp.K323E in exon 7.

We have elucidated a functional deficiency of 11β-hydroxysteroid dehydrogenase type 2 in children with CKD and a subset of essential hypertension. Urinary 5α-THF, 5β-THF, and THE analysis by gas chromatography/mass spectrometry should be a part of routine work-up of CKD and hypertensive patients.

CVD is a major cause of morbidity and mortality in pediatric patients with CKD. It is unclear whether vascular abnormalities in these patients are reversible, and if transplantation portends salutary effects on arterial function. We compared FMD, PWV, AI75, and CIMT in 15 dialysis (D), 14 transplant patients (T), and 15 controls (C), and their associations with cardiovascular risk factors. There was stepwise lower FMD (p < 0.001), higher AI75 (p < 0.001), higher PWV (p = 0.01), and higher CIMT SDS for age (p = 0.03) and height (p = 0.006) in the D group than T and C groups. FMD, PWV, and CIMT were unrelated to dialysis duration or time from transplantation. On multivariate analysis, group status was independently associated with FMD (β = 3.15, p = 0.002), AI75 (β = -5.95, p = 0.01), PWV (β = -0.57, p = 0.07) and CIMT (β = -0.02, p = 0.04) and CIMT SDS for height (β = -0.541, p = 0.009). FMD is lower and AI75, PWV and CIMT are higher in pediatric patients maintained on D than T/C. T patients have similar AI75, PWV and CIMT to C although FMD remains reduced. These findings suggest that transplantation stabilizes or improves CKD associated arteriopathy.

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Case summaryAn 11-year-old African American boy with sickle cell trait (hemoglobin AS) was admitted for evaluation of intermittent painless gross hematuria for 3 months. Initially, the hematuria occurred once every 2 weeks, but it had increased in frequency to two to three times per week. He denied colicky abdominal pain, urinary frequency, or urgency. There was no history of recent trauma. He had never had a urinary tract infection. He was taking no medications and had no recent history of exposure to high altitude. The family history and his review of systems were otherwise unremarkable.Physical examination revealed: weight, 60 kg (>97%); height, 155 cm (95%); temperature, 98°F; heart rate, 87/min; respirations, 18/min; blood pressure, 116/68 mmHg.In general, the patient appeared healthy and not in acute distress. He had no pallor. The abdomen was soft, with mild tenderness in the right upper quadrant. The remainder of the examination was normal.Admission laboratory testing revealed: white blood cell count, 6760/mm 3 ; hemoglobin, 12.3 g/dL; hematocrit, 37.7%; mean corpuscular volume, 73.9 fL; platelet count, 390,000/ mm 3 ; sodium, 135 mmol/L; potassium, 4.2 mmol/L; chloride, 105 mmol/L; bicarbonate, 21 mmol/L; blood urinary nitrogen, 10 mg/dL; creatinine, 0.54 mg/dL; glucose 107 mg/dL; calcium, 9.5 mg/dL; total protein, 7.1 g/dL; albumin, 4.4 g/dL; uric acid, 4 mg/dL; C-reactive protein, 1.4 mg/dL (normal); C3 complement, 78 mg/dL (normal); ratio of urinary calcium to creatinine, 0.05 (normal <0.2). The results from the urine analysis were: yellow, clear, pH 6.5; specific gravity, 1.030; protein, 30 mg/dL; red blood cells (RBC), 20-30 RBC per high power field; nitrites, negative; leukocyte esterase, negative; no casts. Urine culture showed no growth. QuestionsWhat is your differential diagnosis in this patient with sickle cell trait and recurrent macroscopic hematuria? What is the most likely diagnosis in this patient? What test(s) would you order to confirm the diagnosis?The answer to this question can be found at http://dx.