■先天性肾上腺增生(CAH)是一组异质性的肾上腺类固醇生成疾病,具有不同程度的糖皮质激素,盐皮质激素和性类固醇缺乏。CYP11A1基因编码线粒体胆固醇侧链裂解酶(P450scc),通过将胆固醇转化为孕烯醇酮启动类固醇生成的第一个反应。该基因中的变体极为罕见,但由于其在各种类固醇生物合成途径中的早期和关键功能,因此与严重形式的CAH有关。这里,我们报告了一个CYP11A1外显子纯合变体,虽然位置是外来的,通过创建一个额外的异常剪接位点来影响剪接,该剪接位点具有基因的移码和截短。
■先证者是一名23岁的46岁XY女孩。对于一级亲属父母来说,她是正常怀孕的产物。出生后不久,她呕吐了,脱水,低血压,低钠血症和高钾血症。她开始服用糖皮质激素和盐皮质激素,并迅速康复。除了对这些药物的长期需求,她的新生儿和童年史并不引人注目。她在19岁时因原发性闭经和乳房发育不足的青春期延迟而寻求医疗建议。关于评估,她有正常的女性外生殖器,没有乳房发育,睾丸未降,子宫和卵巢缺失。她的荷尔蒙评估显示雌激素非常低,睾丸激素,皮质醇,醛固酮,17-羟基孕酮,和雄烯二酮水平。ACTH,LH,FSH和肾素非常高,与原发性性腺和肾上腺衰竭一致。她的父母是健康的一级堂兄弟。她有三个姐妹,均为46,XX核型。其中一个是临床和生化正常,而另外两个姐妹有正常的女性表型,正常的子宫和卵巢,激素分布与先证者相似,但核型不同(46,XX),并且没有未降睾丸。gDNA用于全外显子组测序(WES)。进行Sanger测序以确认检测到的变体及其与疾病的分离。
■WES在CYP11A1中鉴定出纯合错义变体,改变外显子3第189位的第二个核苷酸(GCG>GTG),并导致丙氨酸变为缬氨酸(p。Ala189Val)。通过PCR和Sanger测序证实该变体。在先证者和她的两个受影响的姐妹中以纯合形式发现,在未受影响的姐妹中以杂合形式发现。计算机分析预测该变体会产生新的剪接位点,并具有基因转录本的移码和截短。这通过分离RNA得到证实,cDNA合成,凝胶电泳和测序。
■我们描述了一个由于CYP11A1变体导致产生新剪接位点而具有非常罕见形式的CAH的家族,蛋白质的移码和过早截断。
UNASSIGNED: Congenital adrenal hyperplasia (CAH) is a heterogeneous group of adrenal steroidogenesis disorders with variable degrees of glucocorticoid, mineralocorticoid and sex steroid deficiencies. CYP11A1 gene encodes the mitochondrial cholesterol side-chain cleavage enzyme (P450scc), which initiates the first reaction in steroidogenesis by converting cholesterol to pregnenolone. Variants in this gene are extremely rare but associated with severe forms of CAH due to its early and critical function in various steroid biosynthesis pathways. Here, we report a CYP11A1 exonic homozygous variant that, although exonic in location, affects splicing by creating an additional aberrant splicing site with frameshift and truncation of the gene.
UNASSIGNED: The proband is a 23-year old 46,XY patient raised as a girl. She was a product of normal pregnancy for first-degree relative parents. Soon after birth, she had vomiting, dehydration, hypotension, hyponatremia and hyperkalemia. She was started on glucocorticoids and mineralocorticoids with prompt recovery. Apart from a chronic need for these medications, her neonatal and childhood history was unremarkable. She sought medical advice at age 19 years for delayed puberty with primary amenorrhea and lack of breast development. On evaluation, she had normal external female genitalia, no breast development, undescended testes and absent uterus and ovaries. Her hormonal evaluation revealed very low estrogen, testosterone, cortisol, aldosterone, 17-hydroxyprogesterone, and androstenedione levels. ACTH, LH, FSH and renin were very high consistent with primary gonadal and adrenal failure. Her parents are healthy first-degree cousins. She has three sisters, all with 46,XX karyotype. One of them is clinically and biochemically normal while the other two sisters have normal female phenotype, normal uterus and ovaries, similar hormonal profile to the proband but different karyotype (46,XX) and absence of undescended testes. gDNA was used for whole exome sequencing (WES). Sanger sequencing was performed to confirm the detected variant and its segregation with the disease.
UNASSIGNED: WES identified a homozygous missense variant in CYP11A1 changing the second nucleotide (GCG > GTG) at position 189 in exon 3 and resulting in a change of Alanine to Valine (p.Ala189Val). This variant was confirmed by PCR and Sanger sequencing. It was found in a homozygous form in the proband and her two affected sisters and in a heterozygous form in the unaffected sister. In-silico analysis predicted this variant to create a new splicing site with frameshift and truncation of the gene transcript. This was confirmed by isolation of RNA, cDNA synthesis, gel electrophoresis and sequencing.
UNASSIGNED: We describe a family with a very rare form of CAH due to a CYP11A1 variant leading to creation of a new splice site, frameshift and premature truncation of the protein.