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Background: Type I collagen is a triple helix structure with two α1 and one α2 chains. Coordinated biosynthesis of α1 and α2 subunits is very important for tissue morphogenesis, growth, and repair. In contrast, abnormal deposition in response to proinflammatory cytokines is associated with organ dysfunction. In humans, COL1A2 contains two microsatellite loci: one located at the 5’-flanking region is composed of poly CA and poly CG; the other located in the 1st intron is constituted of poly GT. Expression of COL1A2 has been noted in gastric cancer and was positively correlated with degree of invasion and metastases. But no genetic study taking into account polymorphism of COL1A2 in uterine fibroids has been undertaken. Methods: In this study, repeated dinucleotide GT n of intron 1 COL1A2 was highlighted in 55 patients with uterine fibroids (UF). Clinical and pathological data were obtained from patient’s records, and other parameters were recorded. Mutation Surveyor version 5.0.1, DnaSP version 5.10, MEGA version 7.0.26, and Arlequin version 3.5.1.3 were used to determine genetics parameters. To estimate genetic variation according to epidemiological parameters, index of genetic differentiation (Fst) and genetic structure (AMOVA) were determined with Arlequin version. Results: Based on reference microsatellite pattern (GT) 14 CT(GT) 3 CT(GT) 3, 15 haplotypes were found. Among the 15 haplotypes, 12 have mutation at position 2284C > G and 7 at position 2292C > G. Insertions of repeated dinucleotide GTn were found on three haplotypes against eight haplotypes in which they are deletions. Intron 1 of COL1A2 gene exhibits high genetic diversity in uterine fibroids with 35.34% polymorphic sites, 95.74% of which were parsimoniously variable and an average number of nucleotide difference of 10.442, which reflects an important genetic variability. According to epidemiological parameters, our results showed, for the first time, a genetic structuring of uterine fibroids according to ethnicity, marital status, use of contraception, diet, and physical activity, beyond confirming the involvement dinucleotide length polymorphism GTn in occurrence of uterine fibroids in Senegalese women. Conclusion: Results obtained open up avenues for understanding the mechanisms involved in the racial variation in the prevalence of uterine fibroids as well as the predisposing factors.

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Fibroadenoma is the most common benign breast tumor in women under 30 years. This study aimed to contribute to the knowledge of the genetic factors involved in the occurrence and progression of mammary fibroadenomas. MED12 and CYP17A1 were sequenced in fibroadenomas and blood in 43 Senegalese women. The Alamut-visual software, which includes the pathogenicity prediction software SIFT, Polyphen2 and MutationTaster, was used to search for mutations. DnaSP version 5.10.01, MEGA version 7.0.14 and Arlequin version 3.5.1.3 were used to determine phylogenetic parameters including indices of genetic variability and diversity and genetic differentiation parameters. A deletion in the poly-A tail of MED12 was identified in our study population. An alteration of Methionine (M1) was observed on exon 1 of CYP17A1. Our results also show that most of the variants found on exon 2 of MED12 and exon 1 of CYP17A1 have the probability of causing the appearance of breast fibroadenomas according by the three pathogenicity prediction software. We found 23 new variants on the MED12 gene and 109 new variants on the CYP17A1 gene. The amino acid frequency distribution between blood and fibroadenomas shows a statistically significant difference in Glycine, Arginine and Valine for MED12 and Cysteine, Phenylalanine, Histidine, Asparagine, Arginine, Tryptophan and Tyrosine for CYP17A1. In addition the selection test shows that codon 20 of exon 1 of CYP17A1 which codes for Arginine (p.20Arg) is under positive selection in mammary fibroadenomas. Genetic differentiation parameters show a clear difference between blood and breast fibroadenomas. These results show for the first time the involvement of the CYP17A1 gene in breast fibroadenomas and confirm the involvement of MED12. Codon 20 of exon 1 of CYP17A1 being under positive selection could be used as a biomarker in breast fibroadenomas.