ECE2019 Poster Presentations Calcium and Bone 1 (60 abstracts)
Biochemical and clinical features of a family with a novel mutation of CYP24A1
Alessandro Brancatella 1 , Daniele Cappellani 1 , Martin Kaufmann 2 , Simona Borsari 1 , Glenville Jones 2 , Claudio Marcocci 1 & Filomena Cetani 1
1Department of Clinical and Experimental Medicine, Endocrine Unit, University of Pisa, Pisa, Italy; 2Department of Biomedical & Molecular Sciences, Queen’s University, Kingston, Canada.
Context: Mutations of cytochrome P450 24 subfamily A member 1 (CYP24A1) gene are associated with Idiopathic Infantile Hypercalcemia (IIH), a disease recently related to vitamin D catabolism impairment.
Aim of the study: Report of clinical and biochemical features of a large family with a novel mutation of CYP24A1.
Methods: We performed dosage of total calcium, ionized calcium, 24 h urinary calcium, PTH, 25-OH-Vitamin D (25-OH-D), and 24–25 Vitamin D, genetic analysis of CYP24A1 and abdomen ultrasound in the proband, a 44 year old man, and in first-degree relatives (Mother, Father, Sister and Two sons). Vitamin D metabolites were analyzed using liquid chromatography mass spectrometry at Queen’s University Laboratory (Kingston, Canada).
Results: The proband showed high levels of total calcium, 25-OH-D, 1,25-(OH)2-D and low levels of PTH, 24,25-(OH)2D3 and 1,24,25-(OH)3D3. 25-OH-D/24-25-OH-D ratio was high (500.5). Abdomen ultrasound showed bilateral nefrolitiasis. Genetic analysis revealed a novel homozygous mutation. In first-degree relatives, serum calcium and 25-OH-vitamin D were in the upper limit of normal range and PTH low. The 25-OH-D/24-25-OH-D ratio was normal. Abdomen ultrasound showed nefrolitiasis only in the sister. Genetic analysis confirmed the mutation in heterozygosity in each member.
| Family members | CYP24A1 Mutation | *Ca2+ (mmol/L) | *PTH (ng/L) | 25-OH-D (ng/mL) | 24,25-(OH)2D3 (ng/mL) | *25D3/24,25D3 | 1,24,25-(OH)3D3 (pg/mL) | 1,25-(OH)2D3 (pg/mL) | Nephro-lithiasis |
| Proband (M 44 yr) | c.667 A>T p.Arg223 Homozygous | 1.34 | 6 | 71.89 | 0.14 | 500.5 | <2 | 68.2 | yes |
| Sister (54 yr) | c.667 A>T p.Arg223 Eterozygous | 1.26 | 14 | 32.26 | 1.54 | 20.6 | 19.7 | 56.6 | yes |
| Son (13 yr) | c.667 A>T p.Arg223 Eterozygous | 1.33 | 12 | 37.55 | 1.83 | 20.4 | 15.6 | 97.2 | no |
| Son 2 (11 yr) | c.667 A>T p.Arg223 Eterozygous | 1.37 | 20 | 40.59 | 1.53 | 26.3 | 10 | 70.4 | no |
| Father (85 yr) | c.667 A>T p.Arg223 Eterozygous | n.a. | n.a | 38.95 | 1.15 | 33.6 | 10.8 | 41.6 | no |
| Mother (82 yr) | c.667 A>T p.Arg223 Eterozygous | n.a. | n.a | 48.93 | 2.37 | 20.5 | 17.2 | 38.3 | no |
| n.a.: not available*Ca2+: normal range 1,12–1,32 mmol/L * PTH: normal range 8-40 ng/L *25D3/24,25D3: normal range < 30. | |||||||||
Conclusions: We report the biochemical and clinical features of a family with a novel CYP24 A1 mutation. Preliminary data suggest that the new mutation is associated with a mild phenotype. However, genetic and environmental factors could contribute in the clinical outcome.
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Endocrine Abstracts
ISSN 1470-3947 (print) | ISSN 1479-6848 (online)
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