Congenital adrenal hyperplasia due to 11β-hydroxylase deficiency is a form of

congenital adrenal hyperplasia Congenital adrenal hyperplasia (CAH) is a group of Genetic disorder#Autosomal recessive, autosomal recessive disorders characterized by impaired cortisol synthesis. It results from the deficiency of one of the five enzymes required for the Biosy ...

(CAH) which produces a higher than normal amount of androgen, resulting from a defect in the

gene In biology, the word gene has two meanings. The Mendelian gene is a basic unit of heredity. The molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protei ...

encoding the

enzyme An enzyme () is a protein that acts as a biological catalyst by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different mol ...

steroid 11β-hydroxylase Steroid 11β-hydroxylase, also known as steroid 11β-monooxygenase, is a steroid hydroxylase found in the zona glomerulosa and zona fasciculata of the adrenal cortex. Named officially the cytochrome P450 11B1, mitochondrial, it is a protein tha ...

(11β-OH) which mediates the final step of

cortisol Cortisol is a steroid hormone in the glucocorticoid class of hormones and a stress hormone. When used as medication, it is known as hydrocortisone. Cortisol is produced in many animals, mainly by the ''zona fasciculata'' of the adrenal corte ...

synthesis in the

adrenal The adrenal glands (also known as suprarenal glands) are endocrine glands that produce a variety of hormones including adrenaline and the steroids aldosterone and cortisol. They are found above the kidneys. Each gland has an outer cortex which ...

. 11β-OH CAH results in

hypertension Hypertension, also known as high blood pressure, is a Chronic condition, long-term Disease, medical condition in which the blood pressure in the artery, arteries is persistently elevated. High blood pressure usually does not cause symptoms i ...

due to excessive

mineralocorticoid Mineralocorticoids are a class of corticosteroids, which in turn are a class of steroid hormones. Mineralocorticoids are produced in the adrenal cortex and influence salt and water balances (electrolyte balance and fluid balance). The primary ...

effects. It also causes excessive

androgen An androgen (from Greek ''andr-'', the stem of the word meaning ) is any natural or synthetic steroid hormone that regulates the development and maintenance of male characteristics in vertebrates by binding to androgen receptors. This includes ...

production both before and after birth and can virilize a genetically female fetus or a child of either sex.

Presentation

Mineralocorticoid effects

Mineralocorticoid Mineralocorticoids are a class of corticosteroids, which in turn are a class of steroid hormones. Mineralocorticoids are produced in the adrenal cortex and influence salt and water balances (electrolyte balance and fluid balance). The primary ...

manifestations of severe 11β-hydroxylase deficient CAH can be biphasic, changing from deficiency (salt-wasting) in early infancy to excess (

) in childhood and adult life. Salt-wasting in early infancy does not occur in most cases of 11β-OH CAH but can occur because of impaired production of

aldosterone Aldosterone is the main mineralocorticoid steroid hormone produced by the zona glomerulosa of the adrenal cortex in the adrenal gland. It is essential for sodium conservation in the kidney, salivary glands, sweat glands, and colon. It plays ...

aggravated by the inefficiency of salt conservation in early infancy. When it occurs it resembles the salt-wasting of severe 21-hydroxylase deficient CAH: poor weight gain and vomiting in the first weeks of life progress and culminate in life-threatening

dehydration In physiology, dehydration is a lack of total body water that disrupts metabolic processes. It occurs when free water loss exceeds intake, often resulting from excessive sweating, health conditions, or inadequate consumption of water. Mild deh ...

hyponatremia Hyponatremia or hyponatraemia is a low concentration of sodium in the Serum (blood), blood. It is generally defined as a sodium concentration of less than 135 mmol/L (135 mEq/L), with severe hyponatremia being below 120 mEq/L. Symp ...

, hyperkalemia, and

metabolic acidosis Metabolic acidosis is a serious electrolyte disorder characterized by an imbalance in the body's acid-base balance. Metabolic acidosis has three main root causes: increased acid production, loss of bicarbonate, and a reduced ability of the kidn ...

in the first month. Despite the inefficient production of aldosterone, the more characteristic mineralocorticoid effect of 11β-OH CAH is hypertension. Progressive adrenal hyperplasia due to persistent elevation of ACTH results in extreme overproduction of 11-deoxycorticosterone (DOC) by mid-childhood. DOC is a weak mineralocorticoid but usually reaches high enough levels in this disease to cause effects of mineralocorticoid excess: salt retention, volume expansion, and

Sex steroid effects

Because 11β-hydroxylase activity is not necessary for the production of

sex steroid Sex hormones, also known as sex steroids, gonadocorticoids and gonadal steroids, are steroid hormones that interact with vertebrate steroid hormone receptors. The sex hormones include the androgens, estrogens, and progestogens. Their effects a ...

s (

s and

estrogen Estrogen (also spelled oestrogen in British English; see spelling differences) is a category of sex hormone responsible for the development and regulation of the female reproductive system and secondary sex characteristics. There are three ...

s), the hyperplastic adrenal cortex produces excessive amounts of

DHEA Dehydroepiandrosterone (DHEA), also known as androstenolone, is an endogenous steroid hormone precursor. It is one of the most abundant circulating steroids in humans. DHEA is produced in the adrenal glands, the gonads, and the brain. It functio ...

androstenedione Androstenedione, or 4-androstenedione (abbreviated as A4 or Δ4-dione), also known as androst-4-ene-3,17-dione, is an endogenous weak androgen steroid hormone and intermediate in the biosynthesis of estrone and of testosterone from dehydroe ...

, and especially

testosterone Testosterone is the primary male sex hormone and androgen in Male, males. In humans, testosterone plays a key role in the development of Male reproductive system, male reproductive tissues such as testicles and prostate, as well as promoting se ...

. These

s produce effects that are similar to those of 21-hydroxylase deficient CAH. In the severe forms, XX (genetically female) fetuses can be markedly virilized, with

ambiguous genitalia Intersex people are those born with any of several Sexual characteristics, sex characteristics, including chromosome patterns, gonads, or sex organ, genitals that, according to the Office of the United Nations High Commissioner for Human ...

that look more male than female, though internal female organs, including

ovaries The ovary () is a gonad in the female reproductive system that produces ova; when released, an ovum travels through the fallopian tube/oviduct into the uterus. There is an ovary on the left and the right side of the body. The ovaries are endocr ...

and

uterus The uterus (from Latin ''uterus'', : uteri or uteruses) or womb () is the hollow organ, organ in the reproductive system of most female mammals, including humans, that accommodates the embryonic development, embryonic and prenatal development, f ...

develop normally. XY fetuses (genetic males) typically show no abnormal features related to androgen excess. A megalopenis (>22 cm/8.7in) is usually present in male patients. In milder mutations, androgen effects in both sexes appear in mid-childhood as early pubic hair, overgrowth, and accelerated bone age. Although " nonclassic" forms causing hirsutism and menstrual irregularities and appropriate steroid elevations have been reported, most have not had verifiable mutations, and mild 11β-hydroxylase deficient CAH is currently considered a very rare cause of hirsutism and infertility. All of the issues related to virilization, neonatal assignment, advantages and disadvantages of genital surgery, childhood and adult virilization, gender identity, and sexual orientation are similar to those of 21-hydroxylase CAH and elaborated in more detail in

Congenital adrenal hyperplasia Congenital adrenal hyperplasia (CAH) is a group of Genetic disorder#Autosomal recessive, autosomal recessive disorders characterized by impaired cortisol synthesis. It results from the deficiency of one of the five enzymes required for the Biosy ...

Pathophysiology

The enzyme that mediates 11β-hydroxylase activity is now known as P450c11β since it is one of the

cytochrome P450 oxidase Cytochromes P450 (P450s or CYPs) are a superfamily of enzymes containing heme as a cofactor that mostly, but not exclusively, function as monooxygenases. However, they are not omnipresent; for example, they have not been found in ''Escherich ...

enzymes located in the inner

mitochondrial A mitochondrion () is an organelle found in the cells of most eukaryotes, such as animals, plants and fungi. Mitochondria have a double membrane structure and use aerobic respiration to generate adenosine triphosphate (ATP), which is used ...

membrane of cells of the adrenal cortex. It is coded by a gene at 8q21-22. Like the other forms of CAH, several different defective alleles for the gene have been identified, producing varying degrees of impaired 11β-hydroxylase activity. Also like the other forms of CAH, 11β-OH CAH is inherited as an autosomal recessive disease. 11β-Hydroxylase mediates the final step of the

glucocorticoid Glucocorticoids (or, less commonly, glucocorticosteroids) are a class of corticosteroids, which are a class of steroid hormones. Glucocorticoids are corticosteroids that bind to the glucocorticoid receptor that is present in almost every vertebra ...

pathway, producing cortisol from 11-deoxycortisol. It also catalyzes the conversion of 11-deoxycorticosterone (DOC) to

corticosterone Corticosterone, also known as 17-deoxycortisol and 11β,21-dihydroxyprogesterone, is a 21-carbon steroid hormone of the corticosteroid type produced in the cortex of the adrenal glands. In the very rare case of congenital adrenal hyperplasia due ...

in the

pathway.

Diagnosis

Classification

''Congenital adrenal hyperplasia'' (CAH) refers to any of several

autosomal An autosome is any chromosome that is not a sex chromosome. The members of an autosome pair in a diploid cell have the same morphology, unlike those in allosomal (sex chromosome) pairs, which may have different structures. The DNA in autosome ...

recessive In genetics, dominance is the phenomenon of one variant (allele) of a gene on a chromosome masking or overriding the effect of a different variant of the same gene on the other copy of the chromosome. The first variant is termed dominant and ...

diseases resulting from defects in steps of the synthesis of cortisol from cholesterol by the

adrenal gland The adrenal glands (also known as suprarenal glands) are endocrine glands that produce a variety of hormones including adrenaline and the steroids aldosterone and cortisol. They are found above the kidneys. Each gland has an outer adrenal corte ...

s. All of the forms of CAH involve excessive or defective production of

s and can prevent or impair the development of

primary Primary or primaries may refer to: Arts, entertainment, and media Music Groups and labels * Primary (band), from Australia * Primary (musician), hip hop musician and record producer from South Korea * Primary Music, Israeli record label Work ...

secondary sex characteristic A secondary sex characteristic is a physical characteristic of an organism that is related to or derived from its sex, but not directly part of its reproductive system. In humans, these characteristics typically start to appear during pubert ...

s in affected infants, children, and adults. Many also involve excessive or defective production of

s, which can cause

or salt wasting, respectively. The most common type of CAH is due to deficiency of 21-hydroxylase. 11β-Hydroxylase deficient congenital adrenal hyperplasia is one of the less common types of CAH due to deficiencies of other proteins and enzymes involved in cortisol synthesis. Other uncommon types are described in individual articles (links below). 11β-OH CAH resembles 21-hydroxylase deficient CAH in its

ic manifestations: partial

virilization Virilization or masculinization is the biological development of adult male characteristics in young males or females. Most of the changes of virilization are produced by androgens. Virilization is a medical term commonly used in three medical a ...

and

of genetically female infants, childhood virilization of both sexes, and rarer cases of virilization or

infertility In biology, infertility is the inability of a male and female organism to Sexual reproduction, reproduce. It is usually not the natural state of a healthy organism that has reached sexual maturity, so children who have not undergone puberty, whi ...

of adolescent and adult women. The

effect differs:

is usually the clinical clue that a patient has 11- rather than 21-hydroxylase CAH. Diagnosis of 11β-OH CAH is usually confirmed by demonstration of marked elevations of 11-deoxycortisol and 11-deoxycorticosterone (DOC), the substrates of 11β-hydroxylase. Management is similar to that of 21-hydroxylase deficient CAH except that mineralocorticoids need not be replaced.

Management

As with other forms of CAH, the primary therapy of 11β-hydroxylase deficient CAH is lifelong

replacement in sufficient doses to prevent

adrenal insufficiency Adrenal insufficiency is a condition in which the adrenal glands do not produce adequate amounts of steroid hormones. The adrenal glands—also referred to as the adrenal cortex—normally secrete glucocorticoids (primarily cortisol), mineraloco ...

and suppress excess mineralocorticoid and androgen production. Salt-wasting in infancy responds to intravenous saline, dextrose, and high dose

hydrocortisone Hydrocortisone is the name for the hormone cortisol when supplied as a medication. It is a corticosteroid and works as an anti-inflammatory and by immune suppression. Uses include conditions such as adrenocortical insufficiency, adrenogenit ...

, but prolonged

fludrocortisone Fludrocortisone, sold under the brand name Florinef among others, is a corticosteroid used to treat congenital adrenal hyperplasia, postural hypotension, and adrenal insufficiency. In adrenal insufficiency, it is generally taken together wit ...

replacement is usually not necessary. The hypertension is ameliorated by glucocorticoid suppression of DOC. Long-term

replacement issues are similar to those of 21-hydroxylase CAH and involve careful balance between doses sufficient to suppress androgens while avoiding suppression of growth. Because the enzyme defect does not affect

synthesis, gonadal function at puberty and long-term fertility should be normal if adrenal androgen production is controlled. See

for a more detailed discussion of androgen suppression and fertility potential in adolescent and adult women.

References

External links

{{Defects of cholesterol and steroid metabolism Autosomal recessive disorders Cholesterol and steroid metabolism disorders Congenital disorders of endocrine system Endocrine-related cutaneous conditions Intersex variations