ESPE Abstracts

Introduction: Neurofibromatosis type 1 (NF-1) is an autosomal dominant disease. The NF-1 gene is located on chromosome 17 and encodes a gene product called neurofibromin. Mutation or deletion of the NF-1 gene results in phenotypic features involving many systems. Hypophosphatasia is a group of inherited disorders characterized by impaired mineralization of bones and/or teeth and low serum alkaline phosphatase (ALP) activity. It occurs as a result of a loss-of-function mutation in the ALPL gene on chromosome 1, which encodes the tissue non-specific isoenzyme of ALP (TNSALP). No case with NF-1 and hypophosphatasia both together has been reported in the literature. We aimed to present our case diagnosed with hypophosphatasia and neurofibromatosis type 1 both together. Case report: The patient was admitted to our endocrine outpatient clinic at the age of 11 years and 10 months due to short stature. The patient, who was diagnosed with NF-1 genetics when he was 6 years old, and was followed up in the neurology and oncology departments, was born at term and weighed 3700 g. There was no consanguinity between his parents. It was learned from his history that he had unilateral hearing loss, specific learning disability and epilepsy. In addition, Arnold Chiari malformation was detected in MRI examinations for NF-1 and he was operated because he had symptoms. In the physical examination of the patient; her weight was 38 kg (-0.95 SDS), her height was 138.8 cm (-2.22 SDS). Her puberty was compatible with tanner stage 2. He had widespread cafe au lait spots on his body. Complete blood count, liver, kidney and thyroid function tests were normal in laboratory tests. Celiac markers were negative. Calcium 10.7 mg/dL, phosphorus 6.2 mg/dL, ALP 63 U/L, PTH 38 ng/L, 25(OH)D vitamin 10 ng/mL. Genetic analysis was performed with the preliminary diagnosis of hypophosphatasia, since the patient had similar low ALP levels in the previous examination results. A c.1354G>A/p.Glu452Lys heterozygous mutation was detected in the ALPL gene. As the patient with no history of fracture described only muscle pain, asphotase alfa treatment for hypophosphatasia was not planned at this time. Conclusion:We diagnosed hypophosphatasia as a result of genetic testing performed on the patient who was followed up for a long time with the diagnosis of neurofibromatosis type-1. We shared this rare case of NF-1 and hypophosphatasia because there was no reported case in the literature.