SNP Shot: Genomic Insights

17 alpha(α)-hydroxylase/17,20-lyase deficiency is a disorder impacting the function of the gonads (ovaries in females, testes in males) and adrenal glands, which are hormone-producing glands. The gonads are crucial for sexual development and reproduction, while the adrenal glands, situated atop the kidneys, regulate hormone production, including those controlling salt levels. This deficiency causes an imbalance in hormone production within these glands. It belongs to a group of conditions called congenital adrenal hyperplasias, which disrupt hormone production, sexual development, and maturation.

The resulting hormone imbalances cause the distinctive signs and symptoms of 17α-hydroxylase/17,20-lyase deficiency, including high blood pressure (hypertension), low potassium levels (hypokalemia), and atypical sexual development. The severity of these features varies, and the condition presents in two forms: the more severe complete 17α-hydroxylase/17,20-lyase deficiency and the less severe partial 17α-hydroxylase/17,20-lyase deficiency.

The impact on sexual development differs between males and females. Females (XX chromosomes) with this deficiency are born with typical external female genitalia, but their internal reproductive organs (uterus and ovaries) may be underdeveloped. Women with the complete form typically do not develop secondary sex characteristics (breasts, pubic hair) and experience absent menstruation (amenorrhea). Women with the partial form might develop some secondary sex characteristics, but menstruation is usually irregular or absent. Both forms lead to infertility.

In chromosomally male individuals (XY chromosomes), sexual development problems lead to external genitalia abnormalities. The most severely affected are born with typically female external genitalia and are often raised as females. However, lacking female internal reproductive organs, they experience amenorrhea and do not develop female secondary sex characteristics. They possess testes, but they are often located abnormally in the abdomen (undescended). Complete 17α-hydroxylase/17,20-lyase deficiency can sometimes result in ambiguous genitalia (not clearly male or female). Males with the partial form usually have abnormal male genitalia, such as a small penis (micropenis), hypospadias (urethral opening on the underside of the penis), or a bifid scrotum (divided scrotum). Both complete and partial forms result in infertility in males.

Inheritance:

The inheritance pattern is autosomal recessive. This means that an affected individual must inherit two copies of the mutated gene, one from each parent. The parents are carriers of the mutated gene but typically do not exhibit signs or symptoms of the condition.