Molecular Genetic Testing
Congenital Adrenal Hyperplasia (21-hydroxylase deficiency, AGS)

Indication and Diagnostic Value

AGS results from inherited defects in one of the enzymatic steps required for the biosynthesis of cortisol. As cortisol represents one of the key regulators of adrenocortcotrophic hormone secretion, a lowered cortisol level leads to a chronic overstimulation of adrenocortcotrophic hormone secretion and results in hyperplasia of the adrenal cortex. Genetically, low cortisol levels can be caused by inherited mutations in the enzyme 21- hydroxylase (CYP21-gene). Subjects heterozygous for 21-hydroxylase deficiency are clinical normal. However, already at birth they manifest a mild degree of increased 17α-hydroxyprogesterone levels. Due to enhanced adrenal sex hormone production females are born with virilized external genitalia. Potentially lethal adrenal insufficiency is characteristic of two-thirds to three-quarters of patients with the classical salt wasting form of AGS. AGS is detected in 1:12 000 live births in Germany. In case when children are known to be carrier of a CYP-2 mutation, or both parents are heterozygous, early therapy by dexamethasone application is recommended. Also, if both parents carry a CYP-2 mutation prenatal genetic testing has to be considered.

Samples and Test Method

5-10 ml EDTA blood must arrive our laboratory within 48 hours after blood collection. Blood stain paper can not be used !
The entire CYP-2 gene will be sequenced. The MLPA assay (Multiplex-Ligation dependent PCR) is used to detect CYP-2 deletions, duplications or conversions. In addition, Southern blot analysis might be necessary to reach an almost 100% test sensitivity.

Turnaround time for this test is 4-6 weeks.

→ list of Molecular Genetic Tests offered by IMMD

 


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