Passage a 6-Day-Old, Genotypically Normal (46,XX) Female Patient Shows Symptoms of of Hypoglycemia

Passage
A 6-day-old, genotypically normal (46,XX) female patient shows symptoms of hypoglycemia (low blood glucose) and hypotonia (decreased muscle tone) .  Physical examination reveals abnormal development of the external genitalia, and laboratory studies show elevated urinary sodium content, increased serum levels of potassium, and abnormal serum concentration of several steroid hormones.  The patient is diagnosed with 21-hydroxylase deficiency, the most common type of congenital adrenal hyperplasia (CAH) .CAH refers to a group of autosomal recessive diseases, each associated with defective production of one or more steroid hormones by the adrenal glands, two crescent-shaped glands located above each kidney in the abdominal cavity.  It has been reported that unequal crossing over involving chromosome 6 can result in CAH.  More than 90% of CAH diagnoses are associated with a deficiency of 21-hydroxylase, an enzyme encoded by the CYP21A2 gene on chromosome 6.Normally, 21-hydroxylase catalyzes chemical reactions involved in the synthesis of aldosterone and cortisol, the principal mineralocorticoid and glucocorticoid hormones, respectively.  As a result, patients with 21-hydroxylase deficiency exhibit diminished serum levels of aldosterone and cortisol.  However, synthesis and secretion of the sex hormone testosterone is excessive.  Glucocorticoid deficiency disrupts the negative feedback loop linking the brain to the adrenal gland, leading to hyperplasia (increased cell proliferation) of adrenal tissue.The patient's 21-hydroxylase deficiency is treated with regular administration of synthetic steroid hormones.  Her condition improves after receiving these medications.
-A 10-day-old male was diagnosed with 21-hydroxylase deficiency despite having normal physical examination results.  Which of the following best explains why physical examination results can be normal in males with this condition?

A) The testes compensate for abnormal adrenal function by synthesizing glucocorticoids.
B) The Y chromosome contains extra copies of genes mutated in CAH.
C) A high serum testosterone level leads to abnormal sexual development only in females.
D) Only female sexual differentiation is dependent on serum glucocorticoids.

Correct Answer:

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