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Introduction: Secondary osteoporosis is due to an identifiable cause of osteoporosis. Hypophosphatasia is a rare cause of secondary osteoporosis and needs to be considered when evaluating osteoporosis in young people. We present a case of secondary osteoporosis initially thought to be a result of malabsorptive disorder and chronic steroid use, with eventual diagnosis of autosomal dominant hypophosphatasia as the primary underlying cause. Clinical Case: A 24 year old male who was seen for evaluation of osteoporosis. He reported an extensive history of fractures about 26 in total, including wrist, shoulders, nose, and metatarsals. Past history was also significant for bowed legs at birth requiring osteotomies and spontaneous loss of several teeth with root intact, requiring extractions. He was also diagnosed with Crohn’s disease at 17 years old and history of steroid use, however was not on steroids at time of initial evaluation. He was diagnosed with bilateral avascular necrosis at age 18 years and needed bilateral hip replacement at age 20 years. There was no family history of skeletal disorders. DEXA scan obtained for the assessment of bone density revealed a Z score of -2.6 in the lumbar spine and -2.1 in the distal forearm. Further evaluation for secondary causes of osteoporosis revealed a normal TSH, PTH, tryptase, vitamin D and testosterone levels. Bone turnover markers were normal except for a low alkaline phosphatase. It was noted that the patient had a persistently low alkaline phosphatase for the last 6 years despite his frequent fractures. Hypophosphatasia was suspected given the history and the low alkaline phosphatase levels. Pyridoxal 5-phosphate was elevated at 77mcg/L (normal 5-50mcg/L). Genetics evaluation revealed a heterozygous, missense mutation in ALPL gene, confirming diagnosis of autosomal dominant hypophosphatasia. He was started on enzyme replacement therapy with asfotase alpha. Conclusion: Hypophosphatasia is a rare metabolic bone disease due to a deficiency of alkaline phosphatase which may present from infancy to adulthood. Diagnosis is made by finding a low alkaline phosphatase level and elevated 5 pyridoxal phosphate. Enzyme replacement therapy with asfotase alpha is the mainstay of treatment. It is probably underdiagnosed secondary to its rarity and therefore must be considered in any young patient who presents with osteoporosis. References: Mornet, E. and Nunes. M.E. Hypophosphatasia. 2007 Nov 20. In: Adam, M.P., Ardinger, H.H., Pagon, R.A., et al., editors. Gene Reviews [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2018. Demay, M.B. and Krane, S.M. 2016. Disorders of Mineralization. In Jameson, J.L., DeGroot, L.J., et al., editors. Endocrinology: Adult and Pediatric. 7th Edition. Philadelphia (PA): Saunders. p 1241.

Autoimmune polyglandular Syndrome Type 1 (APS-1) is an autoimmune disease due to defects in the AIRE gene. It is characterized by a triad of hypoparathyroidism, mucocutaneous candidiasis, and Addison’s disease. We present a case of pigmented paravenous retinochoroidal atrophy associated with APS-1. Case description: A 14 year old female who was admitted for cramps in her hands secondary to hypocalcemia. Past medical history is significant for recurrent vaginal candidiasis and panic attacks. Laboratory assessment revealed low parathyroid hormone and hypocalcemia confirming the diagnosis of hypoparathyroidism. After 4 months she presented with vomiting, and dizziness. Serum cortisol levels were low consistent with the diagnosis of adrenal insufficiency. Further evaluation revealed a mutation in the APS-1 gene. At 28 years she presented with complaints of blurred vision and blind spots for a year. Initial ophthalmologic evaluation revealed a visual acuity of 20/60 in the right eye and 20/50 in the left eye. Anterior segment assessment was normal. Fundoscopy revealed presence of speculated pigment and atrophy of the macula long with attenuated retinal vessels. Optical coherence tomography did not show any macular edema. Visual field assessment was normal. She was diagnosed with pigmented paravenous chorioretinal atrophy. Anti-retinal antibodies were positive for 30-kDa, 36-kDa, 40-kDa, and 46-kDa confirming the autoimmune etiology of the disorder. Over the next 2 years, her visual acuity decreased to 20/400 in the right eye and 20/80 in the left eye. Conclusion: APS-1 is a rare disease associated with numerous autoimmune disorders, beyond the classic clinical triad. Pigmented paravenous chorioretinal atrophy is a previously unreported manifestation of APS-1. Unfortunately no definitive treatment exists for retinal degeneration.