Appeal 2007-1139
Application 10/052,664
A variety of disease conditions are associated with
disorders in Pi metabolism, where such disease conditions
include those characterized by the presence of
hypophosphatemia, e.g. osteomalacia, hypocalciuria and
rickets, and those characterized by the presence of
hyperphosphatemia, e.g. hyperparathyroidism, hypocalcemia,
vitamin D deficiency, soft tissue or metastatic calcification, and
the like. In particular, hyperphosphatemia is a characteristic of
renal disease and failure, and is an underlying cause of many of
the deleterious symptoms observed with such renal
complications.
(Specification1 1-2.)
The invention is drawn to a novel human intestinal sodium phosphate
co-transporter (Npt2B) polypeptide (id. at 3), and methods of treating
disease conditions associated with Npt2B function, that is, conditions
resulting in abnormal serum phosphate levels, such as hypo- and
hyperphosphatemia (id.). The Specification discloses that “[i]n its native
environment, Npt2B is a co-transporter of sodium cation and phosphate
anion. Npt2B is expressed, among other locations, on the surface of
intestinal epithelial cells, i.e. on the apical or intestinal luminal side of the
epithelial cells, and therefore provides for the transport of sodium and
phosphate ions from the intestinal lumen into the intestinal epithelial cells.”
(Id. at 4.)
Based on sequence homology, the Specification discloses that the
claimed Npt2B polypeptide, which is expressed in human small intestine,
appears to be a member of the bovine/flounder type II contransporter
subfamily (id. at 28-29). The Specification also discloses cloning the
1 All references to the Specification are to the Substitute Specification, dated
May 10, 2002.
3
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