Severe osteoporosis with multiple spontaneous vertebral fractures in a young male carrying triple polymorphisms in the vitamin D receptor, collagen type 1, and low-density lipoprotein receptor-related peptide 5 genes.

Osteoporosis is a common disease with a strong genetic component. Several studies have reported the vitamin D receptor (VDR), collagen type I (COL1A1), and LDL receptor-related protein 5 (LRP5) genes as the most likely candidates. However, most of the studies have been carried out in postmenopausal women and older men and show inconsistent results. CASE PRESENTATION: We report a case of a 26-year old male who presented with severe back pain of acute onset, unrelated to any kind of trauma, and diffuse myalgia. Imaging of the lumbar and the thoracic spine revealed two Grade 3, according to Genant's semiquantitative method, vertebral fractures in T10 and T11 and multiple Grade 1 and 2 fractures from T8 to L2. Measurement of bone mineral density (BMD) by dual-energy X-ray absorptiometry (DXA) (Lunar Prodigy) showed severe osteoporosis of the lumbar spine (Z-score=-3.0, BMD = 0.866 gr/cm2). A complete laboratory and biochemical work-up was performed to exclude secondary causes of osteoporosis. Total genomic DNA was extracted from peripheral blood and was used as a template for genotype analysis. The patient was heterozygous for the p.V667M mutation of the LRP5 gene and for the BsmI [g.63980 G→A, rs1544410] and Sp1 polymorphisms [g.6252 G→T, rs1800012] of the VDR and COL1A1 genes, respectively. Further genotype analysis excluded types of osteogenesis imperfecta associated with mutations in the COL1A1 and COL1A2 genes. CONCLUSION: We herein show that the co-existence of three polymorphic sites in the VDR, COL1A1, and LPR-5 genes in a young male adult caused severe osteoporosis with multiple fractures, suggesting a combined effect and/or interaction between these genes.

Functional role of the four different types of (AT)(x)T(y) motifs 5' to the beta-globin gene and their distribution in the Greek population.

The polymorphic sequence (AT)(X)T(Y) motif residing 0.5 kb 5' to the human -globin gene has been shown to be a binding site for a putative repressor protein, BP1, in K562 cells. The (AT)(X)T(Y) sequence is characterized by variable length and several configurations. The precise role of the (AT)(X)T(Y) repeats on the regulation of the -globin gene remains unclear. In the present study, we identified the (AT)(X)T(Y) motifs which prevail in the Greek population, established their frequency, and directly investigated their role on -globin gene expression by comparing the effects of the four identified (AT)(X)T(Y) motifs using transient expression assays. Four different configurations were found in the Greek population: the (AT)7T7 motif was the most abundant (81.8%) representing the reference sequence, the (AT)9T5 motif (16.1%), and the (AT)11T3 motif (2%), while the (AT)8T4 motif was absent from normal A chromosomes and was exclusively found on s chromosomes. To evaluate their different role on transcriptional regulation, the four motifs were subcloned upstream of the luciferase reporter gene. Two expression systems were used; MEL cells were transfected with a pGL-2 basic plasmid containing one of the four (AT)(X)T(Y) repeats, the -globin gene promoter, and the luciferase gene, while HeLa cells were transfected with a similar construct (pGL-2 enhancer) including the SV40 enhancer. After 48 h following transient transfection of the cell lines, the expression level of the reporter gene was estimated using a photoilluminometer. The transfected MEL cells exhibited a clearly reduced expression of the luciferase gene driven by the -globin promoter containing the (AT)9T5 and (AT)11T3 configurations. In contrast, HeLa cells did not exhibit any differences among the four motifs. On the basis of these results, we postulate that the (AT)9T5 and (AT)11T3 variants residing 0.5 kb 5' to the -globin gene do not represent simple polymorphisms and can affect its expression in an erythroid environment.