Iron Therapy for Autosomal Dominant Hypophosphatemic Rickets: A Pilot Project.

Iron will be provided in an open label treatment to all enrolled subjects. Iron levels will
be monitored in blood and doses adjusted with the target of getting the iron levels to or a
little above 100 mcg/dl.

The study will look to see if there is a decrease of FGF23 level. It will also look at how
long does it take to decrease the level of FGF 23 and how long it takes for the serum and
urine phosphate to normalize.

Inclusion Criteria:

- FGF Mutation in either Arginine 176 or arginine 179

- able and willing to provide consent or have a parent that is able/willing to consent,
if a minor

- either serum iron <50mcg/dl (regardless of phosphate or intact FGF23 concentration);
or iron between 500 and 100mcg/dl with serum phosphorus value below 3.0mg/dl for
adults or less than or equal to 0.5 mg/dl the lower limit of normal for age in
children and intact FGF23 about 30pg/ml

- age >2 years

- May be receiving treatment with phosphate and calcitriol, but must be willing to
undergo dose adjustments by the investigators if iron resolves the phosphate wasting
defect.

Exclusion Criteria:

- malignancy within the last 5 years, except treated squamous or basal cell skin
carcinoma

- terminal illness/hospice.

- severe end-organ disease, e.g. cardiovascular, pulmonary, etc, which may limit ability
to complete study.

estimated GFR <45ml/min/1.73m2, calculated using MDRD formula for adults or modified
Schwartz equation for children

- pregnancy or plan on becoming pregnant