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Human disorders of phosphate (Pi) handling and hypophosphatemic rickets have been shown to result from mutations in PHEX, FGF23, and DMP1, presenting as X-linked recessive, autosomal-dominant, and autosomal-recessive patterns, respectively. We present the identification of an inactivating mutation in the ecto-nucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1) gene causing autosomal-recessive hypophosphatemic rickets (ARHR) with phosphaturia by positional cloning. ENPP1 generates inorganic pyrophosphate (PPi), an essential physiologic inhibitor of calcification, and previously described inactivating mutations in this gene were shown to cause aberrant ectopic calcification disorders, whereas no aberrant calcifications were present in our patients. Our surprising result suggests a different pathway involved in the generation of ARHR and possible additional functions for ENPP1.

J Oral Pathol Med (2011) 40: 733–738 Purpose:  To review the literature on primary intraosseous squamous cell carcinoma (PIOSCC) associated with odontogenic cyst. Methods:  All well‐documented cases of PIOSCC published between 1938 and 2010 were collected. Only cases of PIOSCC arising from the lining of an odontogenic cyst, including the keratocystic odontogenic tumor, were selected. Age, sex, signs and symptoms, affected jaw, cyst type, treatment, histopathology, and outcome were recorded. Results:  The mean age was 60.2 years (range 1.3–90). There were 80 (69%) men and 36 (31%) women. Mass and pain were the most common presenting symptoms. The mandible was affected in 92 (79%) patients and the maxilla in 24 (21%). It was a residual/radicular cyst in 70 (60%) patients and a dentigerous cyst or a keratocystic odontogenic tumor in the remaining 40%. The histopathology was well‐differentiated SCC in 53 (46%) patients and moderately differentiated SCC in 47 (40%) patients. Fifty‐three (46%) patients were treated with surgery alone and 44 (38%) with surgery and radiotherapy. Fifty‐eight (62%) patients survived 2 years and 36 (38%) survived 5 years. Conclusion:  PIOSCC has a predilection for men (M/F ratio of 2.22:1), affects mainly adults in their 6–8th decades, occurs most frequently (79%) in the mandible, and is associated mainly with a residual/radicular cyst. Histologically, the well‐to‐moderately differentiated SCC was the most common. Surgery alone or combined therapy of surgery and radiation was the most common approach. The prognosis is 62% surviving 2 years and 38% 5 years.

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