An Intron 9 CYP19 Gene Variant (IVS9+5G>A), Present in an Aromatase Deficient Girl, Affects Normal Splicing, and It Is Also Present in Normal Human Steroidogenic Tissues

SARACCO, N; FRANCA-NESI, S; SAINZ R; MARINO R; MARQUES-PEREIRA R; LA PASTINA J; PEREZ G N; SANDRINI, R; .RIVAROLA MA.,; DE LACERDA L,; BELGOROSKY A

HORMONE RESEARCH

KARGER

Lugar: Basel; Año: 2015

0301-0163

ABSTRACT Background/Aims: Splicing CYP19 gene variants causing aromatase deficiency in 46,XX DSD patients have been reported in few cases. Misbalance between normal and aberrant splicing variants was proposed to explain spontaneous pubertal breast development but incomplete sex maturation progress. The aim of this study is to functional characterize a novel CYP19A1 intronic homozygote mutation (IVS9+5G>A) in a 46,XXDSD girl presenting spontaneous breast development and primary amenorrhea, and to evaluate similar splicing variant expression in normal steroidogenic tissues.Methods: Genomic DNA analysis, splicing prediction programs, splicing assays, in vitro protein expression and enzyme activity were carried out. CYP19A1 mRNA expression in human steroidogenic tissues was also studied. Results: A novel IVS9+5G>A homozygote mutation was found. In silico analysis predicts the disappearance of the splicing donor site in intron 9, confirmed by patient PBL cP450arom and in vitro studies. Protein analysis showed a shorter and inactive protein. The intron 9 transcript variant was also found in human steroidogenic tissues. Conclusions: The mutation IVS9+5G>A generates a splicing variant that includes intron 9 which is also present in normal human steroidogenic tissues, suggesting that a misbalance between normal and aberrant splicing variants might occur in target tissues, explaining the clinical phenotype in the affected patient. Established FactsAromatase, the enzyme complex that catalyzes the synthesis of estrogens from androgens, undergoes different alternative splicing events in the coding region that may lead to both active or inactive proteins in normal and/or in aromatase deficiency tissues. Novel Insights A novel IVS9+5G>A mutation generating a splicing variant that includes intron 9 was found. This was also present in the absence of the mutation in normal steroidogenesis tissues, suggesting that a misbalance between normal and aberrant splicing variants might explain the partial deficiency phenotype.