AIMTo investigate the effects of 1 alpha hydroxylase and serum calcium on the expression of 24-hydroxylase gene in mice kidney.

METHODSMice with targeted deletion of the 25-hydroxyvitamin D 1 alpha hydroxylase gene(1alpha (OH)ase-/-), and the vitamin D receptor gene (VDR-/-) were used. The study of each mutant had two groups which were (1) mutant with high calcium diet, which maintained fertility but left mice hypocalcaemia; (2) mutant with high lactose diet, which normalized calcium in two mutant. Mice in same litter were as control. There were six groups in total and each group had five mice. All mice were killed at 10-week-old. Serum calcium was determined by an autoanalyzer. RNA was isolated from mouse kidney and the express of 1 alpha hydroxylase gene and 24-Hydroxylase gene were studied by RT-PCR.

RESULTSOn the high calcium intake, all mutant animals were hypocalcaemia (1alpha (OH)ase-/- (78 +/- 10.4) mg/L, P < 0.05; VDR-/- (68 +/- 9.8) mg/L, P < 0.05. WT (111 +/- 16.5 mg/L), but when the high lactose diet was administered, serum calcium levels in two mutant mice rose to wild-type levels. The 1 alpha hydroxylase gene was expressed at very higher levels in the vitamin D receptor mutant mice than in wild-type mice when animals received a high calcium intake; This was reduced by eliminating hypocalcaemia with the high lactose diet. Expression of the 24(OH)ase gene was extremely down-regulated in two mutant mice on the high calcium diet but was restored to wild-type levels on the high lactose diet.

CONCLUSIONThe express of 24-hydroxylase gene was directly regulated by serum calcium rather than 1 alpha-hydroxylase. These studies indicate that both the serum calcium and 1 alpha-hydroxylase exert effects on the expression of 24-hydroxylase gene, but 1 alpha-hydroxylase take the effects by elevated the concentration of serum calcium. There are no direct interaction between 1 alpha-hydroxylase gene and 24-hydroxylase gene.

25-Hydroxyvitamin D3 1-alpha-Hydroxylase ; genetics ; Animals ; Calcium ; blood ; Gene Expression ; Mice ; Mice, Knockout ; Serum ; chemistry ; Steroid Hydroxylases ; genetics ; metabolism ; Vitamin D3 24-Hydroxylase

Vitamin D hydroxylation-deficient rickets type 1A (VDDR1A, OMIM 264700) is a rare autosomal recessive inherited disorder. Pathogenic variants in the CYP27B1 gene lead to loss of 1α-hydroxylase activity. We report the case of a 22-month-old toddler who presented with growth retardation and delayed development. The patient exhibited the typical laboratory findings of VDDR1A, including hypocalcemia (calcium: 5.2 mg/dL), elevated serum level of alkaline phosphatase (2,600 U/L), elevated serum level of intact-parathyroid hormone (238 pg/mL), low 1,25(OH)₂D₃ level (11.2 pg/mL), and normal 25(OH)D₃ level (40.7 ng/mL). His height and weight were 76.5 cm and 9.5 kg, respectively (both <3rd percentile). The Bayley Scales of Infant and Toddler Development II indicated significantly delayed development (mental development index <50, psychomotor development index <50). The patient was a compound heterozygous for two novel pathogenic variants in the CYP27B1 gene: c.57_69del (p.Glu20Profs*2) and c.171dupG (p.Leu58Alafs*275), inherited from his mother and father, respectively. The patient showed remarkable improvement after treatment with calcitriol and calcium carbonate.
25-Hydroxyvitamin D3 1-alpha-Hydroxylase ; Alkaline Phosphatase ; Calcitriol ; Calcium Carbonate ; Databases, Genetic ; Fathers ; Humans ; Hypocalcemia ; Infant ; Mothers ; Rickets ; Vitamin D ; Vitamins ; Weights and Measures

Vitamin D hydroxylation-deficient rickets type 1A (VDDR1A) is an autosomal recessively-inherited disorder caused by mutations in CYP27B1 encoding the 1α-hydroxylase enzyme. We report on a female patient with VDDR1A who presented with hypocalcemic seizure at the age of 13 months. The typical clinical and biochemical features of VDDR1A were found, such as hypocalcemia, increased alkaline phosphatase, secondary hyperparathyroidism and normal 25-hydroxyvitamin D3 (25(OH)D₃). Radiographic images of the wrist showed metaphyseal widening with cupping and fraying of the ulna and distal radius, suggesting rickets. A mutation analysis of the CYP27B1 gene identified a homozygous mutation of c.589+1G>A in the splice donor site in intron 3, which was known to be pathogenic. Since that time, the patient has been under calcitriol and calcium treatment, with normal growth and development. During the follow-up period, she did not develop genu valgum, scoliosis, or nephrocalcinosis.
25-Hydroxyvitamin D3 1-alpha-Hydroxylase* ; Alkaline Phosphatase ; Calcifediol ; Calcitriol ; Calcium ; Female ; Follow-Up Studies ; Genu Valgum ; Growth and Development ; Humans ; Hyperparathyroidism, Secondary ; Hypocalcemia ; Introns ; Nephrocalcinosis ; Radius ; Rickets* ; RNA Splice Sites ; Scoliosis ; Seizures ; Ulna ; Vitamin D* ; Vitamins* ; Wrist

OBJECTIVETo investigate the relationship between CYP27B1 gene promoter polymorphism and autoimmune thyroid diseases.

METHODSA case-control study including 158 patients with Graves' disease (GD), 174 patients with Hashimoto's thyroiditis (HT) and 172 matched controls was conducted. Three genotypes of CYP27 B1 gene -1260 site (CC, AA and AC) were determined by restriction fragment length polymorphism (PCR-RFLP) assay and confirmed by sequencing.

RESULTSThe genotypic distribution of CYP27 B1 gene-1260 site showed no deviation from Hardy-Weinberg equilibrium. The genotype and allele frequencies of -1260A/C were CC34.3%, AA19.2%, AC46.5%, C57.6%, and A42.4% in the control group, 48.1%, 13.3%, 38.6%, 67.4%, and 32.6% in GD group, and 47.1%, 10.3%, 42.5%, 68.4%, and 31.6% in HT group, respectively. Significant difference was found in the genotype and allele frequencies in -1260A/C polymorphism between GD and the control groups (Chi2=6.80, P<0.05 for genotype frequencies, and Chi2=6.79, P<0.05 for allele frequencies) and between HT and the control groups (Chi2=8.39, P<0.05 for genotype frequencies, and Chi2=8.71, P<0.05 for allele frequencies).

CONCLUSIONCYP27 B1 promoter -1260 polymorphism is associated with GD or HT in Chinese Han population.

25-Hydroxyvitamin D3 1-alpha-Hydroxylase ; genetics ; Adolescent ; Alleles ; Child ; Female ; Gene Frequency ; Genotype ; Graves Disease ; genetics ; Hashimoto Disease ; genetics ; Humans ; Linkage Disequilibrium ; Male ; Polymerase Chain Reaction ; Polymorphism, Genetic ; Polymorphism, Restriction Fragment Length ; Promoter Regions, Genetic ; genetics ; Thyroiditis, Autoimmune ; genetics

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.
25-Hydroxyvitamin D3 1-alpha-Hydroxylase ; Alkaline Phosphatase ; Alleles ; Calcitriol ; Calcium ; Fathers ; Humans ; Infant ; Lactic Acid ; Male ; Molecular Biology ; Mothers ; Muscle Hypotonia ; Parathyroid Hormone ; Phosphorus ; Radius ; Rickets ; Seizures ; Ulna ; Vitamin D ; Vitamins