Congenital adrenal hyperplasia | |
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Congenital adrenal hyperplasia enzymes. | |
Specialty | Endocrinology |
Symptoms | Excessive urination of sodium, virilism, early, delayed, or absent puberty, hyperandrogenism |
Usual onset | Before birth |
Duration | Lifetime |
Causes | Variants in genes responsible the enzymes required for the synthesis of cortisol in the adrenal cortex |
Congenital adrenal hyperplasia (CAH) is a group of autosomal recessive disorders characterized by impaired cortisol synthesis. [1] [2] It results from the deficiency of one of the five enzymes required for the synthesis of cortisol in the adrenal cortex. [3] Most of these disorders involve excessive or deficient production of hormones such as glucocorticoids, mineralocorticoids, or sex steroids, [4] [2] and can alter development of primary or secondary sex characteristics in some affected infants, children, or adults. [5] It is one of the most common autosomal recessive disorders in humans. [6] [7] [8]
CAH can occur in various forms. The clinical presentation of each form is different and depends to a large extent on the underlying enzyme defect, its precursor retention, and deficient products. [9] Classical forms appear in infancy, and nonclassical forms appear in late childhood. The presentation in patients with classic CAH can be further subdivided into three forms: salt-wasting, simple-virilizing, and non-classic (NC) depending on whether mineralocorticoid deficiency presents or absents, respectively. [10] [11] [12] This subtyping is often not clinically meaningful, though, because all patients lose salt to some degree, and clinical presentations may overlap. [13]
In 75% of cases of severe enzyme deficiency, insufficient aldosterone production can lead to salt wasting, failure to thrive, and potentially fatal hypovolemia and shock. A missed diagnosis of salt-loss CAH is related to the increased risk of early neonatal morbidity and death. [2]
The main feature of CAH in newborn females is the abnormal development of the external genitalia, which has varying degrees of virilization. According to clinical practice guidelines, for newborns found to have bilateral inaccessible gonads, CAH evaluation should be considered. If virilizing CAH cannot be identified and treated, both boys and girls may undergo rapid postnatal growth and virilization. [2]
In addition to the salt-wasting and simple-virilizing forms of CAH diagnosed in infancy, a mild or "nonclassic" form exists, which is characterized by varying degrees of postnatal androgen excess, but is sometimes asymptomatic. [14] The nonclassic form may be noticed in late childhood and may lead to signs of hyperandrogenism such as accelerated growth, acne, hirsutism, premature pubarche, menstrual irregularities, [14] and secondary polycystic ovary syndrome. [15] In adult males, early balding [14] and infertility may suggest the diagnosis. The nonclassic form is characterized by mild subclinical impairment of cortisol synthesis [14] and serum cortisol concentration is usually normal. [14]
The symptoms of CAH vary depending upon the form of CAH and the sex of the patient. Symptoms can include:
Due to inadequate mineralocorticoids:[ citation needed ]
Due to excess androgens:
Due to insufficient androgens and estrogens:[ citation needed ]
CAH results from mutations of genes for enzymes mediating the biochemical steps of production of mineralocorticoids, glucocorticoids, or sex steroids from cholesterol by the adrenal glands (steroidogenesis). [20]
Each form of CAH is associated with a specific defective gene. The most common type (95% of cases) [2] [11] involves the gene for 21-hydroxylase, which is found on 6p21.3 as part of the HLA complex; 21-hydroxylase deficiency results from a unique mutation with two highly homologous near-copies in series consisting of an active gene (CYP21A2) and an inactive pseudogene (CYP21A1P). [21] [22] [23] Mutant alleles result from recombination between the active and pseudogenes (gene conversion). [24] About 5% of cases of CAH are due to defects in the gene encoding 11β-hydroxylase and consequent 11β-hydroxylase deficiency. Other, more rare forms of CAH are caused by mutations in genes, including HSD3B2 (3β-hydroxysteroid dehydrogenase 2), CYP17A1 (17α-hydroxylase/17,20-lyase), [25] CYP11A1 (P450scc; cholesterol side-chain cleavage enzyme), STAR (steroidogenic acute regulatory protein; StAR), CYB5A (cytochrome b5), and CYPOR (cytochrome P450 oxidoreductase; POR).[ citation needed ]
Further variability is introduced by the degree of enzyme inefficiency produced by the specific alleles each patient has. Some alleles result in more severe degrees of enzyme inefficiency. In general, severe degrees of inefficiency produce changes in the fetus and problems in prenatal or perinatal life. Milder degrees of inefficiency are usually associated with excessive or deficient sex hormone effects in childhood or adolescence, while the mildest forms of CAH interfere with ovulation and fertility in adults.[ citation needed ]
This section needs additional citations for verification .(October 2020) |
Female infants with classic CAH have ambiguous genitalia due to exposure to high concentrations of androgens in utero. [26] CAH due to 21-hydroxylase deficiency is the most common cause of ambiguous genitalia in genotypically normal female infants (46XX). Less severely affected females may present with early pubarche. Young women may present with symptoms of polycystic ovarian syndrome (oligomenorrhea, polycystic ovaries, hirsutism).[ medical citation needed ]
Males with classic CAH generally have no signs of CAH at birth. Some may present with hyperpigmentation, due to co-secretion with melanocyte-stimulating hormone, and possible penile enlargement. Age of diagnosis of males with CAH varies and depends on the severity of aldosterone deficiency. Boys with salt-wasting disease present early with symptoms of hyponatremia and hypovolemia. Boys with non-salt-wasting disease present later with signs of virilization. [24]
In rarer forms of CAH, males are undermasculinized [27] and females generally have no signs or symptoms at birth.[ medical citation needed ]
Genetic analysis can be helpful to confirm a diagnosis of CAH, but it is not necessary if classic clinical and laboratory findings are present.
In classic 21-hydroxylase deficiency, laboratory studies will show:
Classic 21-hydroxylase deficiency typically causes 17α-hydroxyprogesterone blood levels >242 nmol/L.[ medical citation needed ] (For comparison, a full-term infant at three days of age should have <3 nmol/L. Many neonatal screening programs have specific reference ranges by weight and gestational age because high levels may be seen in premature infants without CAH.) Salt-wasting patients tend to have higher 17α-hydroxyprogesterone levels than non-salt-wasting patients. In mild cases, 17α-hydroxyprogesterone may not be elevated in a particular random blood sample, but it will rise during a corticotropin stimulation test.
Cortisol is an adrenal steroid hormone required for normal endocrine function. Production begins in the second month of fetal life. Poor cortisol production is a hallmark of most forms of CAH. Inefficient cortisol production results in rising levels of ACTH, because cortisol feeds back to inhibit ACTH production, so loss of cortisol results in increased ACTH. [28] This increased ACTH stimulation induces overgrowth (hyperplasia) and overactivity of the steroid-producing cells of the adrenal cortex. The defects causing adrenal hyperplasia are congenital (i.e. present at birth).
Cortisol deficiency in CAH is usually partial, and not the most serious problem for an affected person. Synthesis of cortisol shares steps with synthesis of mineralocorticoids such as aldosterone, androgens such as testosterone, and estrogens such as estradiol. The resulting excessive or deficient production of these three classes of hormones produce the most important problems for people with CAH. Specific enzyme inefficiencies are associated with characteristic patterns of over- or underproduction of mineralocorticoids or sex steroids.
Since the 1960s, most endocrinologists have referred to the forms of CAH by the traditional names in the left column, which generally correspond to the deficient enzyme activity. As exact structures and genes for the enzymes were identified in the 1980s, most of the enzymes were found to be cytochrome P450 oxidases and were renamed to reflect this. In some cases, more than one enzyme was found to participate in a reaction, and in other cases, a single enzyme mediated in more than one reaction. Variation in different tissues and mammalian species also was found.
In all its forms, congenital adrenal hyperplasia due to 21-hydroxylase deficiency accounts for about 95% of diagnosed cases of CAH. [2] Unless another specific enzyme is mentioned, "CAH" in nearly all contexts refers to 21-hydroxylase deficiency. (The terms "salt-wasting CAH", and "simple virilizing CAH" usually refer to subtypes of this condition.) CAH due to deficiencies of enzymes other than 21-hydroxylase present many of the same management challenges, as 21-hydroxylase deficiency, but some involve mineralocorticoid excess or sex steroid deficiency.
Common medical term | % | OMIM | Enzyme(s) | Locus | Substrate(s) | Product(s) | Mineralocorticoids | Androgens |
---|---|---|---|---|---|---|---|---|
21-Hydroxylase CAH | 95% [2] | 201910 | P450c21 | 6p21.3 | 17-OH-Progesterone→ Progesterone→ | 11-Deoxycortisol DOC | ↓ | ↑ |
11β-Hydroxylase CAH | 5% | 202010 | P450c11β | 8q21-22 | 11-Deoxycortisol→ DOC→ | Cortisol Corticosterone | ↑ | ↑ |
3β-HSD CAH | Very rare | 201810 | 3βHSD2 | 1p13 | Pregnenolone→ 17-OH-Pregnenolone→ DHEA→ | Progesterone 17-OH-Progesterone Androstenedione | ↓ | ↓ |
17α-Hydroxylase CAH | Very rare | 202110 | CYP17A1 | 10q24.3 | Pregnenolone→ Progesterone→ 17-OH-Pregnenolone→ | 17-OH-Pregnenolone 17-OH-Progesterone DHEA | ↑ | ↓ |
Lipoid CAH (20,22-desmolase) | Very rare | 201710 | StAR P450scc | 8p11.2 15q23-q24 | Transport of cholesterol Cholesterol→ | Into mitochondria Pregnenolone | ↓ | ↓ |
Currently, in the United States and over 40 other countries, every child born is screened for 21-hydroxylase CAH at birth. This test detects elevated levels of 17α-hydroxyprogesterone (17-OHP). Detecting high levels of 17-OHP enables early detection of CAH. Newborns detected early enough can be placed on medication and live relatively normal lives.[ citation needed ]
The screening process, however, is characterized by a high false-positive rate. In one study, [30] CAH screening had the lowest positive predictive value (111 true-positive cases among 20,647 abnormal screening results in a 2-year period, or 0.53%, compared with 6.36% for biotinidase deficiency, 1.84% for congenital hypo-thyroidism, 0.56% for classic galactosemia, and 2.9% for phenylketonuria). According to this estimate, 200 unaffected newborns required clinical and laboratory follow-up for every true case of CAH.[ non-primary source needed ]
In 2020, Wael AbdAlmageed from USC Information Sciences Institute and Mimi Kim from USC Keck School Of Medicine led a joint study in which they used deep learning technology to analyze the facial morphology and features of CAH patients compared to control. In this cross-sectional study [31] of 102 patients with CAH and 144 control participants, deep learning methods achieved a mean area under the receiver operating characteristic curve of 92% for predicting CAH from facial images. Facial features distinguished patients with CAH from controls, and analyses of facial regions found that the nose and upper face were most contributory. The findings suggest that facial morphologic features, as analyzed by deep neural network techniques, can be used as a phenotypic biomarker to predict CAH.[ citation needed ]
Since the clinical manifestations of each form of CAH are unique and depend to a large extent on the underlying enzyme defects, their precursor retention and defective products, the therapeutic goal of CAH is to replenish insufficient adrenal hormones and suppress excess of precursors. [9]
Treatment of all forms of CAH may include any of:
If CAH is caused by the deficiency of the 21-hydroxylase enzyme, then treatment aims to normalize levels of androstenedione, but normalization of 17α-hydroxyprogesterone is a sign of overtreatment. [32] Treatment can be monitored by measuring androstenedione and 17α-hydroxyprogesterone levels in blood or saliva. [32]
Crinecerfont, an oral corticotropin-releasing factor type 1 receptor (CRF1) antagonist that reduces ACTH secretion, may allow reduction of daily glucocorticoid dosing to physiologic ranges with adequate maintenance of androstenedione control. [33] [34]
The incidence varies ethnically. In the United States, congenital adrenal hyperplasia in its classic form is particularly common in Native Americans and Yupik Inuit (incidence 1⁄280). Among American Caucasians, the incidence of the classic form is about 1⁄15,000). [24]
Continued treatment and wellness are enhanced by education and follow up. [35]
Italian anatomist, Luigi De Crecchio (1832-1894), provided the earliest known description of a case of probable CAH.
I propose in this narrative that it is sometimes extremely difficult and even impossible to determine sex during life. In one of the anatomical theaters of the hospital..., there arrived toward the end of January a cadaver which in life was the body of a certain Joseph Marzo... The general physiognomy was decidedly male in all respects. There were no feminine curves to the body. There was a heavy beard. There was some delicacy of structure with muscles that were not very well developed... The distribution of pubic hair was typical of the male. Perhaps the lower extremities were somewhat delicate, resembling the female, and were covered with hair... The penis was curved posteriorly and measured 6 cm, or with stretching, 10 cm. The corona was 3 cm long and 8 cm in circumference. There was an ample prepuce. There was a first grade hypospadias... There were two folds of skin coming from the top of the penis and encircling it on either side. These were somewhat loose and resembled labia majora.
De Crecchio then described the internal organs, which included a normal vagina, uterus, fallopian tubes, and ovaries.
It was of the greatest importance to determine the habits, tendencies, passions, and general character of this individual... I was determined to get as complete a story as possible, determined to get at the base of the facts and to avoid undue exaggeration which was rampant in the conversation of many of the people present at the time of the dissection.
He interviewed many people and satisfied himself that Joseph Marzo "conducted himself within the sexual area exclusively as a male", even to the point of contracting the "French disease" (syphilis) on two occasions. The cause of death was another in a series of episodes of vomiting and diarrhea. [36]
This account was translated by Alfred Bongiovanni from De Crecchio ("Sopra un caso di apparenzi virili in una donna". Morgagni 7:154–188, 1865) in 1963 for an article in The New England Journal of Medicine .[ citation needed ]
The association of excessive sex steroid effects with diseases of the adrenal cortex have been recognized for over a century. The term "adrenogenital syndrome" was applied to both sex-steroid producing tumors and severe forms of CAH for much of the 20th century, before some of the forms of CAH were understood. Congenital adrenal hyperplasia, which also dates to the first half of the century, has become the preferred term to reduce ambiguity and to emphasize the underlying pathophysiology of the disorders.[ citation needed ]
Much modern understanding and treatment of CAH comes from research conducted at Johns Hopkins Medical School in Baltimore in the middle of the 20th century. Lawson Wilkins, "founder" of pediatric endocrinology, worked out the apparently paradoxical pathophysiology: that hyperplasia and overproduction of adrenal androgens resulted from impaired capacity for making cortisol. He reported use of adrenal cortical extracts to treat children with CAH in 1950. Genital reconstructive surgery was also pioneered at Hopkins. After application of karyotyping to CAH and other intersex disorders in the 1950s, John Money, JL Hampson, and JG Hampson persuaded both the scientific community and the public [ citation needed ] that sex assignment should not be based on any single biological criterion, and gender identity was largely learned and has no simple relationship with chromosomes or hormones. See Intersex for a fuller history, including recent controversies over reconstructive surgery.[ citation needed ]
Hydrocortisone, fludrocortisone, and prednisone were available by the late 1950s. By 1980, all of the relevant steroids could be measured in blood by reference laboratories for patient care. By 1990, nearly all specific genes and enzymes had been identified. The last decade, though, has seen a number of new developments, discussed more extensively in congenital adrenal hyperplasia due to 21-hydroxylase deficiency:[ citation needed ]
Notable people with CAH include:
The adrenal 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 produces steroid hormones and an inner medulla. The adrenal cortex itself is divided into three main zones: the zona glomerulosa, the zona fasciculata and the zona reticularis.
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, mineralocorticoids, and androgens. These hormones are important in regulating blood pressure, electrolytes, and metabolism as a whole. Deficiency of these hormones leads to symptoms ranging from abdominal pain, vomiting, muscle weakness and fatigue, low blood pressure, depression, mood and personality changes to organ failure and shock. Adrenal crisis may occur if a person having adrenal insufficiency experiences stresses, such as an accident, injury, surgery, or severe infection; this is a life-threatening medical condition resulting from severe deficiency of cortisol in the body. Death may quickly follow.
Lipoid congenital adrenal hyperplasia is an endocrine disorder that is an uncommon and potentially lethal form of congenital adrenal hyperplasia (CAH). It arises from defects in the earliest stages of steroid hormone synthesis: the transport of cholesterol into the mitochondria and the conversion of cholesterol to pregnenolone—the first step in the synthesis of all steroid hormones. Lipoid CAH causes mineralocorticoid deficiency in affected infants and children. Male infants are severely undervirilized causing their external genitalia to look feminine. The adrenals are large and filled with lipid globules derived from cholesterol.
Congenital adrenal hyperplasia due to 11β-hydroxylase deficiency is a form of congenital adrenal hyperplasia (CAH) which produces a higher than normal amount of androgen, resulting from a defect in the gene encoding the enzyme steroid 11β-hydroxylase (11β-OH) which mediates the final step of cortisol synthesis in the adrenal. 11β-OH CAH results in hypertension due to excessive mineralocorticoid effects. It also causes excessive androgen production both before and after birth and can virilize a genetically female fetus or a child of either sex.
Congenital adrenal hyperplasia due to 3β-hydroxysteroid dehydrogenase deficiency is an uncommon form of congenital adrenal hyperplasia (CAH) resulting from a mutation in the gene for one of the key enzymes in cortisol synthesis by the adrenal gland, 3β-hydroxysteroid dehydrogenase (3β-HSD) type II (HSD3B2). As a result, higher levels of 17α-hydroxypregnenolone appear in the blood with adrenocorticotropic hormone (ACTH) challenge, which stimulates adrenal corticosteroid synthesis.
Congenital adrenal hyperplasia due to 17α-hydroxylase deficiency is an uncommon form of congenital adrenal hyperplasia (CAH) resulting from a mutation in the gene CYP17A1, which produces the enzyme 17α-hydroxylase. It causes decreased synthesis of cortisol and sex hormones, with resulting increase in mineralocorticoid production. Thus, common symptoms include mild cortisol deficiency, ambiguous genitalia in men or amenorrhea at puberty in women, and hypokalemic hypertension. However, partial (incomplete) deficiency often has inconsistent symptoms between patients, and affected women may be asymptomatic except for infertility.
Congenital adrenal hyperplasia due to 21-hydroxylase deficiency (CAH) is a genetic disorder characterized by impaired production of cortisol in the adrenal glands.
17α-Hydroxyprogesterone (17α-OHP), also known as 17-OH progesterone (17-OHP), or hydroxyprogesterone (OHP), is an endogenous progestogen steroid hormone related to progesterone. It is also a chemical intermediate in the biosynthesis of many other endogenous steroids, including androgens, estrogens, glucocorticoids, and mineralocorticoids, as well as neurosteroids.
17α-Hydroxypregnenolone is a pregnane (C21) steroid that is obtained by hydroxylation of pregnenolone at the C17α position. This step is performed by the mitochondrial cytochrome P450 enzyme 17α-hydroxylase (CYP17A1) that is present in the adrenal and gonads. Peak levels are reached in humans at the end of puberty and then decline. High levels are also achieved during pregnancy. It is also a known neuromodulator.
Cytochrome P450 17A1 is an enzyme of the hydroxylase type that in humans is encoded by the CYP17A1 gene on chromosome 10. It is ubiquitously expressed in many tissues and cell types, including the zona reticularis and zona fasciculata of the adrenal cortex as well as gonadal tissues. It has both 17α-hydroxylase and 17,20-lyase activities, and is a key enzyme in the steroidogenic pathway that produces progestins, mineralocorticoids, glucocorticoids, androgens, and estrogens. More specifically, the enzyme acts upon pregnenolone and progesterone to add a hydroxyl (-OH) group at carbon 17 position (C17) of the steroid D ring, or acts upon 17α-hydroxyprogesterone and 17α-hydroxypregnenolone to split the side-chain off the steroid nucleus.
Steroid 21-hydroxylase is a protein that in humans is encoded by the CYP21A2 gene. The protein is an enzyme that hydroxylates steroids at the C21 position on the molecule. Naming conventions for enzymes are based on the substrate acted upon and the chemical process performed. Biochemically, this enzyme is involved in the biosynthesis of the adrenal gland hormones aldosterone and cortisol, which are important in blood pressure regulation, sodium homeostasis and blood sugar control. The enzyme converts progesterone and 17α-hydroxyprogesterone into 11-deoxycorticosterone and 11-deoxycortisol, respectively, within metabolic pathways which in humans ultimately lead to aldosterone and cortisol creation—deficiency in the enzyme may cause congenital adrenal hyperplasia.
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 that in humans is encoded by the CYP11B1 gene. The enzyme is involved in the biosynthesis of adrenal corticosteroids by catalyzing the addition of hydroxyl groups during oxidation reactions.
11-Deoxycortisol, also known as cortodoxone (INN), cortexolone as well as 17α,21-dihydroxyprogesterone or 17α,21-dihydroxypregn-4-ene-3,20-dione, is an endogenous glucocorticoid steroid hormone, and a metabolic intermediate toward cortisol. It was first described by Tadeusz Reichstein in 1938 as Substance S, thus has also been referred to as Reichstein's Substance S or Compound S.
Adrenal gland disorders are conditions that interfere with the normal functioning of the adrenal glands. Your body produces too much or too little of one or more hormones when you have an adrenal gland dysfunction. The type of issue you have and the degree to which it affects your body's hormone levels determine the symptoms.
An inborn error of steroid metabolism is an inborn error of metabolism due to defects in steroid metabolism.
Maria Iandolo New(1928-2024) was a professor of Pediatrics, Genomics and Genetics at Icahn School of Medicine at Mount Sinai in New York City. She is an expert in congenital adrenal hyperplasia (CAH), a genetic condition affecting the adrenal gland that can affect sexual development.
21-Deoxycortisol, also known as 11β,17α-dihydroxyprogesterone or as 11β,17α-dihydroxypregn-4-ene-3,20-dione, is a naturally occurring, endogenous steroid related to cortisol (11β,17α,21-trihydroxyprogesterone) which is formed as a metabolite from 17α-hydroxyprogesterone via 11β-hydroxylase.
11β-Hydroxyprogesterone (11β-OHP), also known as 21-deoxycorticosterone, as well as 11β-hydroxypregn-4-ene-3,20-dione, is a naturally occurring, endogenous steroid and derivative of progesterone. It is a potent mineralocorticoid. Syntheses of 11β-OHP from progesterone is catalyzed by the steroid 11β-hydroxylase (CYP11B1) enzyme, and, to a lesser extent, by the aldosterone synthase enzyme (CYP11B2).
Late onset congenital adrenal hyperplasia (LOCAH), also known as nonclassic congenital adrenal hyperplasia, is a milder form of congenital adrenal hyperplasia (CAH), a group of autosomal recessive disorders characterized by impaired cortisol synthesis that leads to variable degrees of postnatal androgen excess.
The androgen backdoor pathway is responsible for the synthesis of physiologically relevant androgens. This process starts with 21-carbon steroids, also known as pregnanes, and involves a step called "5α-reduction". Notably, this pathway does not require the intermediate formation of testosterone, hence the term "bypassing testosterone" is sometimes used in medical literature as the hallmark feature of this way of androgen biosynthesis. This feature is a key distinction from the conventional, canonical androgenic pathway, which necessitates the involvement of testosterone as an intermediate in the synthesis of androgens.
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