Congenital adrenal hyperplasia


Congenital adrenal hyperplasia is a group of autosomal recessive disorders characterized by impaired cortisol synthesis. It results from the deficiency of one of the five enzymes required for the synthesis of cortisol in the adrenal cortex. Most of these disorders involve excessive or deficient production of hormones such as glucocorticoids, mineralocorticoids, or sex steroids, and can alter development of primary or secondary sex characteristics in some affected infants, children, or adults. It is one of the most common autosomal recessive disorders in humans.

Types

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. Classical forms appear in infancy and nonclassical forms appear in late childhood. The presentation in patients with classic CAH can be further subdivided into two forms: salt-wasting and simple-virilizing depending on whether mineralocorticoid deficiency is present or absent, respectively. This subtyping is often not clinically meaningful, though, because all patients lose salt to some degree, and clinical presentations may overlap.

Classic

Salt-wasting

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.

Simple-virilizing

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.

Nonclassic

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. 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, and secondary polycystic ovary syndrome. In adult males, early balding and infertility may suggest the diagnosis. The nonclassic form is characterized by mild subclinical impairment of cortisol synthesis and serum cortisol concentration is usually normal.

Signs and symptoms

The symptoms of CAH vary depending upon the form of CAH and the sex of the patient. Symptoms can include:
Due to inadequate mineralocorticoids:
Due to excess androgens:
Due to insufficient androgens and estrogens:

Genetics

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.
Each form of CAH is associated with a specific defective gene. The most common type 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 and an inactive pseudogene. Mutant alleles result from recombination between the active and pseudogenes. 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, CYP17A1,'' CYP11A1, STAR, CYB5A, and CYPOR ''.

Expressivity

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.

Diagnosis

Clinical evaluation

Female infants with classic CAH have ambiguous genitalia due to exposure to high concentrations of androgens in utero. CAH due to 21-hydroxylase deficiency is the most common cause of ambiguous genitalia in genotypically normal female infants. Less severely affected females may present with early pubarche. Young women may present with symptoms of polycystic ovarian syndrome.
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.
In rarer forms of CAH, males are undermasculinized and females generally have no signs or symptoms at birth.

Laboratory studies

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. 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.

Classification

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. This increased ACTH stimulation induces overgrowth and overactivity of the steroid-producing cells of the adrenal cortex. The defects causing adrenal hyperplasia are congenital.
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. Unless another specific enzyme is mentioned, "CAH" in nearly all contexts refers to 21-hydroxylase deficiency. 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%OMIMEnzymeLocusSubstrateProductMineralocorticoidsAndrogens
21-Hydroxylase CAH95%P450c216p21.317-OH-Progesterone→
Progesterone→		11-Deoxycortisol
DOC		↓↑
11β-Hydroxylase CAH5%P450c11β8q21-2211-Deoxycortisol→
DOC→		Cortisol
Corticosterone		↑↑
3β-HSD CAHVery rare3βHSD21p13Pregnenolone→
17-OH-Pregnenolone→
DHEA→		Progesterone
17-OH-Progesterone
Androstenedione		↓↓
17α-Hydroxylase CAHVery rareCYP17A110q24.3Pregnenolone→
Progesterone→
17-OH-Pregnenolone→		17-OH-Pregnenolone
17-OH-Progesterone
DHEA		↑↓
Lipoid CAH
Very rareStAR
P450scc		8p11.2
15q23-q24		Transport of cholesterol
Cholesterol→		Into mitochondria
Pregnenolone		↓↓

Screening

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. 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.
The screening process, however, is characterized by a high false-positive rate. In one study, CAH screening had the lowest positive predictive value. According to this estimate, 200 unaffected newborns required clinical and laboratory follow-up for every true case of CAH.
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 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.

Treatment

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.
Treatment of all forms of CAH may include any of:
  1. Supplying enough glucocorticoid to reduce hyperplasia and overproduction of androgens or mineralocorticoids
  2. Providing replacement mineralocorticoid and extra salt if the person is deficient
  3. Providing replacement testosterone or estrogens at puberty if the person is deficient
  4. Additional treatments to optimize growth by delaying puberty or delaying bone maturation
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. Treatment can be monitored by measuring androstenedione and 17α-hydroxyprogesterone levels in blood or saliva.
Crinecerfont was approved for medical use in the United States in December 2024.

Epidemiology

The incidence varies ethnically. In the United States, congenital adrenal hyperplasia in its classic form is particularly common in Native Americans and Yupik Inuit.
Continued treatment and wellness are enhanced by education and follow up.

History

Before the twentieth century

Italian anatomist Luigi De Crecchio provided the earliest known description of a case of probable CAH.
De Crecchio then described the internal organs, which included a normal vagina, uterus, fallopian tubes, and ovaries.
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" on two occasions. The cause of death was another in a series of episodes of vomiting and diarrhea.
This account was translated by Alfred Bongiovanni from De Crecchio in 1963 for an article in The New England Journal of Medicine.

Twentieth and twenty-first centuries

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.
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 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.
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:
  1. Debate over the value of genital reconstructive surgery and changing standards
  2. Debate over sex assignment of severely virilized XX infants
  3. New treatments to improve height outcomes
  4. Newborn screening programs to detect CAH at birth
  5. Increasing attempts to treat CAH before birth

Society and culture

People with CAH

Notable people with CAH include: