ESPE Abstracts

Background: VDDR-II, is an autosomal recessive disorder characterized by the early onset of rickets with hypocalcemia, secondary hyperparathyroidism and hypophosphatemia and is caused by mutations in the vitamin D receptor (VDR) gene.

Objective and hypotheses: 2 years old Turkish girl first offspring of consanguineous parents admitted to the hospital for the evaluation of total alopecia and bilaterally genu varum deformity. She was born with normal pilosity, hair loss was observed at 3 months, and alopecia was completed by 6 months. Her motor and mental development was normal and she had used daily oral 400 IU vitamin D regularly until 1 year old.

Method: In her physical examination; weight was 9.2 kg (SDS: −2.1), height was: 78.5 cm (SDS: −1.31). She had frontal bossing, prominence of costochondral junctions, widening of wrists, and bilaterally genu varum deformity.

Results: She had serum calcium of 9.4 mg/dl (8.5–10), phosphorus of 2.2 mg/dl (3–5.5), ALP of 988 U/l (100–350), PTH of 778 pg/ml (12–60), 25(OH) D3 of 32 pg/ml (20–100). Blood gas analyses, renal and tubular functions tests were normal. X-ray of the left hand wrist and lower extremities were compatible with severe rickets. Molecular analysis of VDR gene revealed the presence of a novel homozygous missense mutation (S360P). Her parents were heterozygote for the same mutation. Functional analysis is continuing for this mutation.

Conclusion: The clinical spectrum of VDRR-II varies widely, probably reflecting the type of mutation within the vitamin D receptor and the amount of residual vitamin D receptor activity. S360P mutation in the vitamin D receptor may be associated with normocalcemic VDRR-II.