• Clinical and Experimental Pediatrics
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• v.54 no.2
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• pp.51-54
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• 2011

Vitamin D is present in two forms, ergocalciferol (vitamin $D_2$) produced by plants and cholecalciferol (vitamin $D_3$) produced by animal tissues or by the action of ultraviolet light on 7-dehydrocholesterol in human skin. Both forms of vitamin D are biologically inactive pro-hormones that must undergo sequential hydroxylations in the liver and the kidney before they can bind to and activate the vitamin D receptor. The hormonally active form of vitamin D, 1,25-dihydroxyvitamin D3 $[1,25(OH)_2D]$, plays an essential role in calcium and phosphate metabolism, bone growth, and cellular differentiation. Renal synthesis of $1,25(OH)_2D$ from its endogenous precursor, 25-hydroxyvitamin D (25OHD), is the rate-limiting and is catalyzed by the $1{\alpha}$-hydroxylase. Vitamin D dependent rickets type I (VDDR-I), also referred to as vitamin D $1{\alpha}$-hydroxylase deficiency or pseudovitamin D deficiency rickets, is an autosomal recessive disorder characterized clinically by hypotonia, muscle weakness, growth failure, hypocalcemic seizures in early infancy, and radiographic findings of rickets. Characteristic laboratory features are hypocalcemia, increased serum concentrations of parathyroid hormone (PTH), and low or undetectable serum concentrations of $1,25(OH)_2D$ despite normal or increased concentrations of 25OHD. Recent advances have showed in the cloning of the human $1{\alpha}$-hydroxylase and revealed mutations in its gene that cause VDDR-I. This review presents the biology of vitamin D, and $1{\alpha}$-hydroxylase mutations with clinical findings.

• Clinical and Experimental Pediatrics
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• v.48 no.6
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• pp.665-668
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• 2005

"Rickets" is the term applied to impaired mineralization at epiphyseal growth plate, resulting in deformity and impaired linear growth of long bones. Rickets may arise as a result of vitamin D deficiency or abnormality in metabolism. Vitamin D-dependent rickets(VDDR) is rare autosomal recessive disorder in which affected individuals have clinical features of vitamin D deficiency. In 1961, Prader first described this disorder including severe clinical features of rickets, such as hypophosphatemia, hypocalcemia, muscle weakness and seizure. Two distinctive hereditary defects, type I VDDR and type II VDDR have been recognized in vitamin D metabolism. Type I VDDR may be due to congenital defects of renal 1 ${\alpha}$-hydroxylase, the enzyme responsible for conversion of $25(OH)D_3$. These patients have low to detectable $1,25(OH)_2D_3$ in presence of normal to raised $25(OH)D_3$. In type II VDDR, renal production of $1,25(OH)_2D_3$ is intact but $1,25(OH)_2D_3$ is not used effectively and target organ resistant to $1,25(OH)_2D_3$ is respectively derived from the abnormality in the vitamin D receptor. We report a case of a 25 month-old girl with typical clinical features of VDDR type I rickets, hypocalcemia, increased alkaline phosphatase and secondary hyperparathyroidism.

• Childhood Kidney Diseases
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• v.23 no.2
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• pp.111-115
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• 2019

Vitamin D dependent rickets type 1A (VDDR1A) is an autosomal recessive disorder caused by mutations in CYP27B1. Clinical findings are growth retardation, hypotonia, muscle weakness, hypocalcemic seizures, and radiological features of rickets. We aimed to present the VDDR1A case with a genetic study of CYP27B1. The 14-month-old boy was admitted to the hospital due to a seizure. Serum calcium, phosphorus, alkaline phosphatase, parathyroid hormone (PTH), 25(OH) vitamin D, and 1,25(OH)2 vitamin D values were 5.1 mg/dL, 3.7 mg/dL, 705 IU/L, 429 pg/mL, 24.9 ng/mL, and 8.8 pg/mL, respectively. Radiological study showed cupping and fraying of the distal ulna and radius. The molecular genetic study revealed that the patient had a compound heterozygous mutation, $Phe443Profs^*24$ and c.589+1G>A, in CYP27B1. Genetic analysis of the family members presented that the mother was heterozygous for the mutation c.589+1G>A, and that the father was heterozygous for $Phe443Profs^*24$. The patient was treated with calcium lactate and calcitriol. Until now, six Korean patients with VDDR1A have been studied. Including this case, Korean patients with VDDR1A were found to have only three different mutations in 14 alleles, indicating that the mutation in the CYP27B1 gene is homogeneous in the Korean population.

• Journal of the korean academy of Pediatric Dentistry
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• v.27 no.1
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• pp.108-112
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• 2000

Hypophosphatemic rickets is lack of reponse to physiologic doses of vitamin D, different from the vitamin D-dependent rickets. It is inherited in an X-linked dominant fashion. The prime features of this disorder are lowered serum phosphate levels, elevated serum alkaline phosphatase and normal serum calcium levels. The dental manifestation often include apical radiolucencies, abscess and fistulas of clinically sound teeth. Dental radiographs show ricketic bone trabeculations, abscent or abnormal lamina dura and abnormal cementum. This case which was diagnosed to hypophosphatemic rickets, showed multiple spontaneous periapical abscess and gingival fistula enlarged pulp chambers, extension of the pulp horns into the cusp tips and delayed eruption.

• Childhood Kidney Diseases
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• v.12 no.1
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• pp.111-115
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• 2008

Vitamin D-dependent rickets(VDDR) is a rare autosomal disorder, characterized by hypocalcemia, hypophosphatemia, increased alkaline phosphatase, secondary hyperparathyroidism and many other clinical features. Type I VDDR is due to congenital defects of renal 1${\alpha}$-hydroxylase, the enzyme responsible for the conversion of 25-(OH)D3 to 1,25-$(OH)_2D3$. Type II VDDR arise from target organ resistance to 1,25-$(OH)_2D3$. Unilateral renal aplasia is generally thought to result from a lack of induction of the metanephric blastema from the ureteral bud, which may be secondary to ureteral bud maldevelopment and/or to a problem with the formation of the mesonephric duct. The incidence of unilateral renal aplasia is approximately 1/500-3,200. Type 1 VDDR associated with unilateral renal aplasia has not been reported yet. Thus we report a case of a 3 month old female infant diagnosed as type 1 VDDR with unilateral aplasia of kidney.