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Case No. 07-2888

Case No. 07-2888. Crystal L. Johnson North Carolina State University College of Veterinary Medicine. Signalment and History. Seven month old intact female Pomeranian dog Weakness and muscle tremors progressing to seizures Generalized non-pruritic alopecia Short stature, bowing of forelegs

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Case No. 07-2888

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  1. Case No. 07-2888 Crystal L. Johnson North Carolina State University College of Veterinary Medicine Presented at SEVPAC 2008 – Permission granted for use on SEVPAC website only

  2. Signalment and History • Seven month old intact female Pomeranian dog • Weakness and muscle tremors progressing to seizures • Generalized non-pruritic alopecia • Short stature, bowing of forelegs • Hypocalcemia Presented at SEVPAC 2008 – Permission granted for use on SEVPAC website only

  3. Treatment History Presented at SEVPAC 2008 – Permission granted for use on SEVPAC website only

  4. Normal Littermate and Patient Presented at SEVPAC 2008 – Permission granted for use on SEVPAC website only

  5. RadiologicalFindings • Smooth marginated zones of increased lucency in distal radial and ulnar physes • Metaphyses and epiphyses are widened with adjacent bone sclerosis Presented at SEVPAC 2008 – Permission granted for use on SEVPAC website only

  6. Maxilla Presented at SEVPAC 2008 – Permission granted for use on SEVPAC website only

  7. Costochondral Junctions Presented at SEVPAC 2008 – Permission granted for use on SEVPAC website only

  8. Radius Presented at SEVPAC 2008 – Permission granted for use on SEVPAC website only

  9. Nasal Turbinates Presented at SEVPAC 2008 – Permission granted for use on SEVPAC website only

  10. Normal Physis vs. Patient Physis Presented at SEVPAC 2008 – Permission granted for use on SEVPAC website only

  11. Irregular Cartilage Proliferation Presented at SEVPAC 2008 – Permission granted for use on SEVPAC website only

  12. Reduced Zone of Hypertrophy Presented at SEVPAC 2008 – Permission granted for use on SEVPAC website only

  13. Increased Osteoclasts and Decreased Osteoblasts Presented at SEVPAC 2008 – Permission granted for use on SEVPAC website only

  14. Reduction of Trabeculae, Diaphysis Presented at SEVPAC 2008 – Permission granted for use on SEVPAC website only

  15. T11 Compression Fracture Presented at SEVPAC 2008 – Permission granted for use on SEVPAC website only

  16. Damage to Spinal Cord Presented at SEVPAC 2008 – Permission granted for use on SEVPAC website only

  17. Diagnosis • Radius: Failure of endochondral ossification (Vitamin D-resistant rickets, Type II) • Patient fibroblasts were submitted to Stanford University and diagnosis was confirmed • Failure of calcitriol to induce the enzyme 25-hydroxyvitamin D3 24-hydroxylase in fibroblasts in vitro can serve as the diagnosis for vitamin D-resistant rickets (VDRR) Presented at SEVPAC 2008 – Permission granted for use on SEVPAC website only

  18. Vitamin D-Resistant Rickets (VDRR) • Two forms are recognized • Type I is inborn error in conversion of vitamin D to its active form due to deficiency of the renal 1-hydroxylase enzyme • Responds to large doses of vitamin D • Type II is an end organ resistance to the active form of vitamin D • Does not respond to vitamin D Presented at SEVPAC 2008 – Permission granted for use on SEVPAC website only

  19. Vitamin D Receptor Location • Cholecalciferol (skin or ingestion)  calcidiol (liver)  calcitriol (kidney) • Major target tissues for vitamin D are small intestine, bone, and kidney • Secondary tissues with receptors include skin, pancreas, parathyroid gland, stomach, gonads, brain, monocytes, and activated T and B lymphocytes Presented at SEVPAC 2008 – Permission granted for use on SEVPAC website only

  20. VDRR Receptor Defects • Decreased number of cytosolic receptors • Deficient maximal hormonal binding • Deficient hormone binding affinity • Normal binding but undetectable nuclear localization • Abnormal DNA-binding domain for the calcitriol receptor Presented at SEVPAC 2008 – Permission granted for use on SEVPAC website only

  21. VDRR Features and Treatment • Alopecia occurs in 50% of human cases and is a marker for more severe form of disease • An unexplained feature of the disease is the tendency for calcium levels to normalize and for the radiographic abnormalities to improve • Large continuous parenteral doses of calcium “overcome” the receptor defect and maintain bone remodeling • Treatment is cost prohibitive in veterinary medicine Presented at SEVPAC 2008 – Permission granted for use on SEVPAC website only

  22. Acknowledgements • Dr. Keith Linder • Dr. Linda Kooistra • Dr. Dana Levine • Dr. Stuart Hunter • NCSU Histology Laboratory, especially Monica Mattmuller • All my resident mates Vitamin D molecule 3dchem.com Presented at SEVPAC 2008 – Permission granted for use on SEVPAC website only

  23. Questions? Presented at SEVPAC 2008 – Permission granted for use on SEVPAC website only BigWorldPhoto.com

  24. References • Tanner E, Langley-Hobbs, SJ. “Vitamin D-Dependent Rickets Type 2 with Characteristic Radiographic Changes in a 4-month-old Kitten.” Journal of Feline Medicine and Surgery 7 (2005): 307-11. • Koren R. “Vitamin D Receptor Defects: The Story of Hereditary Resistance to Vitamin D.” Pediatric Endocrinology Review Supp. 3 (2006): 470-5. • Malloy PJ, Xu R, Peng L, Peleg S, AL-Ashwal A, Feldman D. “Hereditary 1,25-Dihydroxyvitamin D Resistant Rickets Due to a Mutation Causing Multiple Defects in Vitamin D Receptor Function.” Endocrinology 145 (2004): 5106-14. • Stacy BA, Parker JM. “Lack of the Vitamin D Receptor is Associated with Reduced Epidermal Differentiation and Hair Follicle Growth.” Journal of Investigative Dermatology 118 (2002): 11-16. Presented at SEVPAC 2008 – Permission granted for use on SEVPAC website only

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