Hypophosphatemic rickets in opsismodysplasia.
BACKGROUND
Opsismodysplasia is a rare spondylo(epi)chondrodysplasia characteristized by delayed skeletal maturation and a constellation of dysplastic features. Although metaphyseal irregularities/cupping have been noted, neither renal phosphate wasting nor rickets have previously been reported.


OBJECTIVE
To evaluate hypophosphatemia and rickets in opsismodysplasia.


METHODS
Two girls with opsismodysplasia presenting with hypophoshpatemia by 3 years of age.


METHODS
Routine biochemistries to assess hypophosphatemia and renal phosphate wasting; radiographs (rachitic changes) and DEXA scan (BMD); FGF23 levels, PHEX and FGF23 gene analyses performed (Patient 1).


RESULTS
Both children had hypophosphatemia, decreased TRP, and rickets. Oral phosphorus and calcitriol improved metaphyseal mineralization, yet serum phosphate levels remained relatively low and renal phosphate wasting persisted. PHEX and FGF23 gene analyses were negative, whereas serum FGF23 levels were markedly elevated in Patient 1.


CONCLUSIONS
We now demonstrate an association between opsismodysplasia, hypophosphatemic rickets, and FGF23 elevation. Screening phosphorus levels may thus uncover a potentially treatable component of this disease.
Zeger
Martha Dechert
MD
Pediatrics, Thomas Jefferson University, Philadelphia, PA, USA.
Adkins
Deanna
D
Fordham
Lynn A
LA
White
Kenneth E
KE
Schoenau
Eckhard
E
Rauch
Frank
F
Loechner
Karen J
KJ
D002675:Child, Preschool; D005260:Female; D000089703:Fibroblast Growth Factor-23; D005346:Fibroblast Growth Factors / Q000097:blood; D006801:Humans; D017674:Hypophosphatemia / Q000150:complications / Q000175:diagnosis*; D010009:Osteochondrodysplasias / Q000150:complications / Q000175:diagnosis* / Q000000981:diagnostic imaging; D011859:Radiography; D012279:Rickets / Q000150:complications / Q000175:diagnosis* / Q000000981:diagnostic imaging
C000717427:FGF23 protein, human; D005346:Fibroblast Growth Factors; D000089703:Fibroblast Growth Factor-23