ESPE Abstracts (2021) 94 P2-63

ESPE2021 ePoster Category 2 Bone, growth plate and mineral metabolism (41 abstracts)

Diagnostic Challenges of Vitamin D-Dependent Rickets Type 1A (VDDR1A) caused by CYP27B1 mutation in Resource Limited Countries: A Case Series from Three families

Sommayya Aftab 1,2 , Tahir Shaheen 1 , Muhammad Nadeem Anjum 3 , Ahmed Imran 4 , Anjum Saeed 3 , Abid Ali Qureshi 4 & Huma Arshad Cheema 3

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1Department of Paediatric Endocrinology & Diabetes, The Children’s Hospital & The Institute of Child Health, Lahore, Pakistan; 2Department of Paediatric Endocrinology & Diabetes, Hameed Latif Hospital, Lahore, Pakistan; 3Department of Paediatric Gastroenterology & Hepatology, The Children’s Hospital & The Institute of Child Health, Lahore, Pakistan; 4Department of Paediatric Radiology, The Children’s Hospital & The Institute of Child Health, Lahore, Pakistan


Background & Aim: Vitamin D-dependent rickets type 1 A (VDDR1A) is an autosomal recessive condition caused by mutation in CYP27B1, which encodes 1 α-hydroxylase enzyme that catalyzes the conversion of 25-hydroxyvitamin D (25OHD) to 1,25-dihydroxyvitamin D (1,25 (OH)2D). We are reporting 4 cases of VDDR1A due to CYP27B1 mutation initially misdiagnosed as vitamin D deficient and hypophosphatemic rickets.

Case Summaries: We identified 4 cases (all male) from 3 different families of VDDR1A due to homozygous CYP27B1 mutation (c.1319_1325dup p.(Phe443Profs*24)) over 1 year. All were born to consanguineous parents with one case had a history of 4 siblings’ death. Initial presentation was bony deformities and failure to thrive in late infancy (9- 12 months). Three had additional complaints of abdominal distension with repeated diarrheas and one had a history of fracture after minor trauma. All were initially misdiagnosed as vitamin D deficient rickets and hypophosphatemic rickets (treated with cholecalciferol and joule’s solution) and referred to tertiary care at mean age of 2.8 (1.5-3.9) year because of failure to respond to treatment. At presentation mean height was at -4.10 (-2.10 to -4.88) SD and BMI was at -0.18 (1.96 to -1.84) SD. All cases had signs of frank rickets and three had abdominal distension with hepatomegaly. Bone profile revealed low-normal calcium (7.9-8.9 mg/dl), low phosphate (1.5-2.2 mg/dl), normal magnesium (2-2.5mg/dl), raised Alkaline phosphatase (868 – 3723 IU/l), normal to raised 25-OHD level (39.8-122 ng/ml) and raised PTH (80.9- 771 pg/ml). Fractional excretion of phosphate was > 15% (17%-23%) and tubular reabsorption of phosphate was <85% (76-84%). 1,25 (OH)2D were not done due to non-availability. Skeletal survey showed florid rickets with marked osteopenia. After genetic confirmation of VDDR1A due to CYP27B, joule solution was stopped, and alfacalcidol was started at the dose of 150 ng/kg/day along with calcium supplementation. Two months post-treatment follow up showed they are catching up with mean height velocity 7.7 (4.06-12.3) cm/year, normalization of calcium and phosphorus, decreasing trend of alkaline phosphatase and PTH, normal urine calcium to creatinine ratio and x-ray showing interval improvement with zone of healing.

Conclusion: VDDR1A is often missed and presented late in resource limited countries due to lack of availability of 1,25 (OH)2D level and genetic testing. It is easily treatable condition with excellent outcome if diagnosed timely and managed promptly.

Volume 94

59th Annual ESPE (ESPE 2021 Online)

Online,
22 Sep 2021 - 26 Sep 2021

European Society for Paediatric Endocrinology 

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