SNP Shot: Genomic Insights

X-linked adrenal hypoplasia congenita is a birth defect (congenital) affecting the adrenal glands, which are endocrine glands located on top of the kidneys. These glands are crucial for producing hormones that regulate vital bodily functions, including the stress response.

A key symptom is adrenal insufficiency, where the adrenal glands don't produce enough hormones. Typically starting in infancy or childhood, it can lead to vomiting, feeding problems, dehydration, dangerously low blood sugar (hypoglycemia), and shock. Without treatment, these complications can be fatal.

Individuals with this condition may also have insufficient male sex hormones, leading to underdeveloped reproductive organs, undescended testicles (cryptorchidism), delayed puberty, and infertility. This combination of features is referred to as hypogonadotropic hypogonadism.

The appearance and intensity of these symptoms can differ, even among family members with the condition.

Inheritance:

The inheritance pattern for this condition is X-linked recessive. X-linked conditions occur when the responsible gene is on the X chromosome, one of the sex chromosomes. Males, with only one X chromosome, develop the condition with just one altered gene copy per cell. Females, with two X chromosomes, require a variant in both gene copies to develop the condition. X-linked recessive disorders are far more common in males than females. Notably, fathers cannot transmit X-linked traits to their sons.

In X-linked recessive inheritance, a female with one altered gene copy in each cell is a carrier. She can pass the altered gene on, but typically doesn't show symptoms. However, in rare instances, female carriers of an *NR0B1* gene variant may experience adrenal insufficiency or symptoms of hypogonadotropic hypogonadism, such as underdeveloped reproductive tissues, delayed puberty, and absence of menstruation.