1/2. An unusual patient with hypercalciuria, recurrent nephrolithiasis, hypomagnesemia and G227R mutation of Paracellin-1. An unusual patient with hypercalciuria and hypomagnesemia unresponsive to thiazide diuretics.A 19-year-old female patient with hypercalciuria and recurrent nephrolithiasis/urinary tract infection unresponsive to thiazide type diuretics is presented. The patient first experienced nephrolithiasis at the age of 4 years. Afterwards, recurrent passages of stones and urinary tract infection occurred. On diagnostic evaluation at the age of 19 years, she also had hypocitraturia and hypomagnesemia. Her serum calcium concentrations were near the lower limit of normal (8.5-8.8 mg/dl; normal range: 8.5-10.5), her serum magnesium concentrations were 1.15-1.24 mg/dl (normal range: 1.4-2.5) and urinary calcium excretion was 900 mg/24 h. PTH concentrations were increased (110-156 pg/ml; normal range: 10-65). We tried to treat the patient with hydrochlorothiazide at a dose of 50 mg/day. During treatment with thiazide diuretics, PTH concentration remained high and the patient had recurrent urinary tract infections and passages of stones. serum magnesium concentration did not normalize even under the parenteral magnesium infusion. Her mother had a history of nephrolithiasis 20 years ago. Severe hypomagnesemia in association with hypercalciuria/urinary stones is reported as a rare autosomal recessive disorder caused by impaired reabsorption of magnesium and calcium in the thick assending limp of Henle's loop. Recent studies showed that mutations in the CLDN16 gene encoding paracellin-1 cause the disorder. In exon 4, a homozygous nucleotide exchange (G679C) was identified for the patient. This results in a point mutation at position Glycine227, which is replaced by an arginine residue (G227R). The mother was heterozygous for this mutation. G227 is located in the fourth transmembrane domain and is highly conserved in the claudin gene family. This case indicates the pathogenetic role of paracellin-1 mutation in familial hypomagnesemia with hypercalciuria and nephrocalcinosis and further underlines the risk of stone formation in heterozygous mutation carriers.- - - - - - - - - - ranking = 1keywords = dent (Clic here for more details about this article) |
2/2. Two cases of familial hypomagnesemia with hypercalciuria and nephrocalcinosis: dental findings.BACKGROUND: The authors describe dental and periodontal conditions of two Chinese sisters affected by familial hypomagnesemia with hypercalciuria and nefrocalcinosis (FHHNC). FHHNC is a rare syndrome, genetically investigated since 1999, transmitted as an autosomal recessive disease. It is related to a mutation of PCN-1 gene which encodes for a tight junction protein named paracellin. CASE REPORT: Oral examination of two Chinese patients showed marked enamel hypoplasia, acute gingivitis and periodontal bone loss and severe malocclusion. The literature does not report previous investigations about the dental conditions of FHHNC patients. The syndrome is not definitely described from the clinical point of view. CONCLUSION: Further researches are necessary to understand the linkage between bone loss and enamel structure anomalies in FHHNC and to discover the relationships between nefrocalcinosis, hypomagnesemia, hypercalciuria and amelogenesis imperfecta.- - - - - - - - - - ranking = 6keywords = dent (Clic here for more details about this article) |