STAR splicing mutations cause the severe phenotype of lipoid congenital adrenal hyperplasia: insights from a novel splice mutation and review of reported cases

Camats Tarruella, Núria; Pandey, Amit Vikram; Fernández-Cancio, Mónica; Fernández, Juan M.; Ortega, Ana M.; Udhane, Sameer Sopanrao; Andaluz, Pilar; Audí, Laura; Flück, Christa (2014). STAR splicing mutations cause the severe phenotype of lipoid congenital adrenal hyperplasia: insights from a novel splice mutation and review of reported cases. Clinical endocrinology, 80(2), pp. 191-199. Blackwell Scientific Publications 10.1111/cen.12293

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OBJECTIVE The steroidogenic acute regulatory protein (StAR) transports cholesterol to the mitochondria for steroidogenesis. Loss of StAR function causes lipoid congenital adrenal hyperplasia (LCAH) which is characterized by impaired synthesis of adrenal and gonadal steroids causing adrenal insufficiency, 46,XY disorder of sex development (DSD) and failure of pubertal development. Partial loss of StAR activity may cause adrenal insufficiency only. PATIENT A newborn girl was admitted for mild dehydration, hyponatremia, hyperkalemia and hypoglycaemia and had normal external female genitalia without hyperpigmentation. Plasma cortisol, 17OH-progesterone, DHEA-S, androstendione and aldosterone were low, while ACTH and plasma renin activity were elevated, consistent with the diagnosis of primary adrenal insufficiency. Imaging showed normal adrenals, and cytogenetics revealed a 46,XX karyotype. She was treated with fluids, hydrocortisone and fludrocortisone. DESIGN, METHODS AND RESULTS Genetic studies revealed a novel homozygous STAR mutation in the 3' acceptor splice site of intron 4, c.466-1G>A (IVS4-1G>A). To test whether this mutation would affect splicing, we performed a minigene experiment with a plasmid construct containing wild-type or mutant StAR gDNA of exons-introns 4-6 in COS-1 cells. The splicing was assessed on total RNA using RT-PCR for STAR cDNAs. The mutant STAR minigene skipped exon 5 completely and changed the reading frame. Thus, it is predicted to produce an aberrant and shorter protein (p.V156GfsX19). Computational analysis revealed that this mutant protein lacks wild-type exons 5-7 which are essential for StAR-cholesterol interaction. CONCLUSIONS STAR c.466-1A skips exon 5 and causes a dramatic change in the C-terminal sequence of the protein, which is essential for StAR-cholesterol interaction. This splicing mutation is a loss-of-function mutation explaining the severe phenotype of our patient. Thus far, all reported splicing mutations of STAR cause a severe impairment of protein function and phenotype.

Item Type:

Journal Article (Original Article)

Division/Institute:

04 Faculty of Medicine > Department of Gynaecology, Paediatrics and Endocrinology (DFKE) > Clinic of Paediatric Medicine
04 Faculty of Medicine > Pre-clinic Human Medicine > BioMedical Research (DBMR) > Unit Childrens Hospital > Forschungsgruppe Endokrinologie / Diabetologie / Metabolik (Pädiatrie)
04 Faculty of Medicine > Pre-clinic Human Medicine > BioMedical Research (DBMR) > DCR Unit Tiefenau Hospital (discontinued)

UniBE Contributor:

Camats Tarruella, Núria; Pandey, Amit Vikram; Udhane, Sameer Sopanrao and Flück, Christa

Subjects:

500 Science > 570 Life sciences; biology
600 Technology > 610 Medicine & health

ISSN:

0300-0664

Publisher:

Blackwell Scientific Publications

Funders:

[4] Swiss National Science Foundation

Projects:

[102] Pathogenesis of disorders caused by human P450 oxidoreductase mutations Official URL

Language:

English

Submitter:

Amit Vikram Pandey

Date Deposited:

05 Jun 2014 10:45

Last Modified:

05 Nov 2015 14:07

Publisher DOI:

10.1111/cen.12293

PubMed ID:

23859637

BORIS DOI:

10.7892/boris.41741

URI:

https://boris.unibe.ch/id/eprint/41741

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