Verification of diagnosis. A, Sanger sequencing chromatograms. Left is the forward (sense) sequence; right is the reverse sequence. An arrowhead marks the mutated nucleotide that introduced a TGA translation termination codon (asterisk). B, Blood and urine chemistry results at age 16 years. *Urine analyses. †Reference values are from the Mayo Clinic, Mayo Medical Laboratories, http://www.mayomedicallaboratories.com/. ALPL, alkaline phosphatase; iPTH, intact parathyroid hormone; WNL, within normal limits.