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What is Vitamin D Dependent Rickets type 1A (1 alpha hydroxylase deficiency) (VDDR1A)
Vitamin D Dependent Rickets type 1A is due to a defect in certain enzymes which are responsible for the synthesis of the active form of vitamin D.
This condition is caused by a mutation in the CYP27B1 gene.
Synonyms
- 1 alpha hydroxylase deficiency
- Vitamin D Dependent Rickets, Type 1A
- 1 alpha , 25-Hydroxyvitamin D3 Deficiency Selective
- 25 Hydroxycholecalciferol 1 Hydroxylase Deficiency
- Vitamin D Dependency, Type 1 VDD1
- Pseudovitamin D Deficiency Rickets, Type IA PDDR1A
- PDDR IA
Prevalence at birth
1/2,000
Very frequent in the French Canadian population in the Saguenay region of Quebec
Age of onset
Infancy, Neonatal
Symptoms of Vitamin D Dependent Rickets type 1A
Mandatory symptoms
- Hypocalcemia
- Low serum calcitriol
- Rickets
Very common symptoms
- Bone pain
- Deformed rib cage
- Delayed epiphyseal ossification
- Elevated alkaline phosphatase of bone origin
- Elevated circulating parathyroid hormone level
- Enlargement of the ankles
- Enlargement of the costochondral junction
- Enlargement of the wrists
- Failure to thrive
- Femoral bowing
- Flat occiput
- Generalized aminoaciduria
- Genu varum
- Hypophosphatemia
- Increased susceptibility to fractures
- Irregular, rachitic-like metaphyses
- Motor delay
- Muscle weakness
- Osteomalacia
- Postnatal growth retardation
- Rachitic rosary
- Secondary hyperparathyroidism
- Sparse bone trabeculae
- Subperiosteal bone resorption
- Tetany
- Thin bony cortex
- Tibial bowing
- Wide cranial sutures
Common Symptoms
- Difficulty walking
- Frontal bossing
- Generalized hypotonia
- Short stature
Rare Symptoms
- Delayed eruption of teeth
- Hypocalcemic seizures
- Hypoplasia of dental enamel
- Irritability
- Protuberant abdomen
Prognosis of Vitamin D Dependent Rickets type 1A
Prognosis is very good with timely treatment
Treatment
Daily administration of large doses of vitamin D and physiologic doses of calcitriol