title: Combined pulmonary hypertension and renal thrombotic microangiopathy in cobalamin C deficiency.
abstract: Pulmonary arterial hypertension (PAH) and renal thrombotic microangiopathy (rTMA) are rare diseases in childhood, frequently leading to death and end-stage renal disease, respectively. Their combined occurrence has been reported anecdotally. We investigated the clinical, biochemical, and genetic aspects of 5 children with the rare combination of PAH and rTMA. Onset of disease ranged from 1.5 to 14 years of age. The 2 youngest patients presented with concomitant pulmonary and renal disease; in the older patients, PAH was preceded by rTMA from age 2.5 to 7 years. Three patients presenting at ≤ 3 years of age died of right ventricular failure secondary to progressive PAH. In 2 patients, cobalamin C (cblC) deficiency was diagnosed postmortem. Three patients were treated with hydroxocobalamin; 1 died 2 weeks after diagnosis, 1 patient exhibited progressive pulmonary vasculopathy, and 1 patient is currently in stable condition. cblC deficiency was diagnosed biochemically 2 days to 18 years after initial presentation. Genetic analysis confirmed mutations in MMACHC in all patients; 4 patients were compound heterozygous, with all having base-pair substitutions (G>A or G>T) at nucleotide 276 in addition to frame-shift mutations. One patient had homozygous nonsense mutations of MMACHC. We established cblC deficiency as the denominator in the rare combination of PAH and rTMA in these children. Early recognition of cblC deficiency and vigorous treatment with hydroxocobalamin may beneficially affect the course of this devastating disease.
authors.affiliation: Department of Pediatric Nephrology, Beatrix Children's Hospital, University Medical Centre Groningen, University of Groningen, Hanzeplein 1, 9700 RB Groningen, Netherlands. m.komhoff@umcg.nl.
authors.forename: Martin
authors.initials: M
authors.lastname: Kömhoff
authors.forename: Marcus T
authors.initials: MT
authors.lastname: Roofthooft
authors.forename: Dineke
authors.initials: D
authors.lastname: Westra
authors.forename: Thea K
authors.initials: TK
authors.lastname: Teertstra
authors.forename: Attilio
authors.initials: A
authors.lastname: Losito
authors.forename: Nicole C A J
authors.initials: NC
authors.lastname: van de Kar
authors.forename: Rolf M F
authors.initials: RM
authors.lastname: Berger
mesh_terms: D000293:Adolescent; D002352:Carrier Proteins / Q000235:genetics; D002675:Child, Preschool; D004252:DNA Mutational Analysis; D003937:Diagnosis, Differential; D018450:Disease Progression; D042241:Early Diagnosis; D017809:Fatal Outcome; D005260:Female; D005500:Follow-Up Studies; D006463:Hemolytic-Uremic Syndrome / Q000150:complications / Q000175:diagnosis / Q000188:drug therapy / Q000235:genetics; D006801:Humans; D006879:Hydroxocobalamin / Q000627:therapeutic use; D006976:Hypertension, Pulmonary / Q000150:complications* / Q000175:diagnosis / Q000188:drug therapy / Q000235:genetics; D007223:Infant; D007668:Kidney / Q000098:blood supply*; D008297:Male; D010088:Oxidoreductases; D050721:Proto-Oncogene Proteins c-cbl / Q000172:deficiency* / Q000235:genetics; D057049:Thrombotic Microangiopathies / Q000150:complications* / Q000175:diagnosis / Q000188:drug therapy / Q000235:genetics; D014806:Vitamin B 12 Deficiency / Q000150:complications* / Q000175:diagnosis / Q000188:drug therapy / Q000235:genetics
chemical_list: D002352:Carrier Proteins; C508359:MMACHC protein, human; D010088:Oxidoreductases; D050721:Proto-Oncogene Proteins c-cbl; C119570:CBLC protein, human; D006879:Hydroxocobalamin
keywords: atypical hemolytic uremic syndrome; cobalamin C deficiency; pulmonary arterial hypertension; renal thrombotic microangiopathy