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

Abstract

Background/Aims: Splicing CYP19 gene variants causing aromatase deficiency in 46,XX disorder of sexual development (DSD) patients have been reported in a few cases. A misbalance between normal and aberrant splicing variants was proposed to explain spontaneous pubertal breast development but an incomplete sex maturation progress. The aim of this study was to functionally characterize a novel CYP19A1 intronic homozygote mutation (IVS9+5G>A) in a 46,XX DSD 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, and in vitro protein expression and enzyme activity analyses 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 peripheral leukocyte 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.

Aromatase Deficiency due to a Novel Mutation in CYP19A1 Gene

“…Aromatase deficiency is an autosomal recessive disorder and was first described by Shozu et al ( 5 ). To date, a total of 36 cases from various ethnic origins have been reported in the literature ( 1 , 2 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 ). In patients with aromatase deficiency, more than 30 distinct mutations have been identified in the CYP19A1 gene, including missense, nonsense, small deletions and insertions, splice-site mutations, and one large intragenic deletion ( 1 , 2 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 ).…”

Aromatase Deficiency due to a Homozygous <b><i>CYP19A1</i></b> Mutation in a 46,XX Egyptian Patient with Ambiguous Genitalia

“…These mutations include missense, nonsense, small deletions and insertions and splice site mutations, and 1 large intragenic deletion [Lanfranco et al, 2008;Belgorosky et al, 2009;Hauri-Hohl et al, 2011;Verma et al, 2012;Ludwikowski et al, 2013;Gagliardi et al, 2014;Bouchoucha et al, 2014;Chen et al, 2015;Marino et al, 2015;Saraco et al, 2015;Akçurin et al, 2016;Zhu et al, 2016]. The majority of mutations identified are located in exons 9 and 10, which encode the substrate (androgen)-binding site and haem-binding domains, respectively [Gagliardi et al, 2014].…”

“…The biological importance of aromatase is also related to its potential role in maintaining the androgen-estrogen ratio in different tissues. In humans, the cP450arom enzyme is located in the endoplasmic reticulum of many tissues such as the syncytiotrophoblast layer of the placenta, adipose tissue, bone, gonads, brain, coronary arteries, and various fetal tissues, such as liver, skin, intestine, testis, and ovary [Bulun et al, 2003;Santen et al, 2009;Saraco et al, 2015]. Aromatase is encoded by the CYP19A1 gene, which is located on chromosome 15q21.1 and consists of 9 coding exons (exons 2-10).…”

A Novel Homozygous <i>CYP19A1</i> Gene Mutation: Aromatase Deficiency Mimicking Congenital Adrenal Hyperplasia in an Infant without Obvious Maternal Virilisation

“…In humans, cP450arom is encoded by a single gene (CYP19A1) , that is located on chromosome 15q21.1. The protein-coding sequence is contained within nine exons (E2-E10), spanning approximately 35 kb (1,2,3). The CP450arom enzyme is mainly located in the endoplasmic reticulum of estrogen-producing cells in the ovary, placenta, testis, brain, adipose tissue, liver, muscle and hair follicles (4,5).…”

“…Aromatase deficiency is a rare, autosomal recessive disorder in which affected patients do not have normal estrogen synthesis (1). During pregnancy, dehydroepiandrosterone sulphate (DHEAS) and 16OH-DHEAS, arising from the fetal adrenal gland and liver, respectively, become important sources for the synthesis of placental estrogens (4,5,6).…”