Congenital adrenal hyperplasia due to 11-beta-hydroxylase deficiency

What it is, symptoms and effects

From: MedlinePlus Genetics, National Library of Medicine

Congenital adrenal hyperplasia (CAH) due to 11-beta-hydroxylase deficiency is one of a group of disorders (collectively called congenital adrenal hyperplasia) that affect the adrenal glands. The adrenal glands are located on top of the kidneys and produce a variety of hormones that regulate many essential functions in the body. In people with CAH due to 11-beta-hydroxylase deficiency, the adrenal glands produce excess androgens, which are male sex hormones.

There are two types of CAH due to 11-beta-hydroxylase deficiency, the classic form and the non-classic form. The classic form is the more severe of the two types.

Females with the classic form of CAH due to 11-beta-hydroxylase deficiency have external genitalia that do not look clearly male or female (atypical genitalia). However, the internal reproductive organs develop normally. Males and females with the classic form of this condition have early development of their secondary sexual characteristics such as growth of facial and pubic hair, deepening of the voice, appearance of acne, and onset of a growth spurt. The early growth spurt can prevent growth later in adolescence and lead to short stature in adulthood. In addition, approximately two-thirds of individuals with the classic form of CAH due to 11-beta-hydroxylase deficiency have high blood pressure (hypertension). Hypertension typically develops within the first year of life.

Females with the non-classic form of CAH due to 11-beta-hydroxylase deficiency have normal female genitalia. As affected females get older, they may develop excessive body hair growth (hirsutism) and irregular menstruation. Males with the non-classic form of this condition do not typically have any signs or symptoms except for short stature. Hypertension is not a feature of the non-classic form of CAH due to 11-beta-hydroxylase deficiency.

Causes and biological mechanisms

From: MedlinePlus Genetics, National Library of Medicine

Mutations in the CYP11B1 gene cause CAH due to 11-beta-hydroxylase deficiency. The CYP11B1 gene provides instructions for making an enzyme called 11-beta-hydroxylase. This enzyme is found in the adrenal glands, where it helps produce hormones called cortisol and corticosterone. Cortisol has numerous functions, such as maintaining blood sugar (glucose) levels, protecting the body from stress, and suppressing inflammation. Corticosterone gets converted to the hormone aldosterone, which helps control blood pressure by maintaining proper salt and fluid levels in the body.

CAH due to 11-beta-hydroxylase deficiency is caused by a shortage (deficiency) of the 11-beta-hydroxylase enzyme. When 11-beta-hydroxylase is lacking, precursors that are used to form cortisol and corticosterone build up in the adrenal glands and are converted to androgens. The excess production of androgens leads to abnormalities of sexual development, particularly in females with CAH due to 11-beta-hydroxylase deficiency. A buildup in the precursors used to form corticosterone increases salt retention, leading to hypertension in individuals with the classic form of CAH due to 11-beta-hydroxylase deficiency.

The amount of functional 11-beta-hydroxylase enzyme that an individual produces typically determines the extent of abnormal sexual development. Individuals with the classic form of the condition usually have CYP11B1 gene mutations that result in the production of an enzyme with low levels of function or no function at all. Individuals with the non-classic form of the condition typically have CYP11B1 gene mutations that lead to the production of an enzyme with moderately reduced function. The severity of the signs and symptoms of sexual development do not appear to be related to the severity of the hypertension.

Inheritance and family implications

From: MedlinePlus Genetics, National Library of Medicine

This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition.

How common is it?

From: MedlinePlus Genetics, National Library of Medicine

CAH due to 11-beta-hydroxylase deficiency accounts for 5 to 8 percent of all cases of congenital adrenal hyperplasia. It is estimated that CAH due to 11-beta-hydroxylase deficiency occurs in 1 in 100,000 to 200,000 newborns. This condition is more common in Moroccan Jews living in Israel, occurring in approximately 1 in 5,000 to 7,000 newborns. The classic form of CAH due to 11-beta-hydroxylase deficiency appears to be much more common than the non-classic form.

Reported clinical features and what the terms mean

The following findings are associated with this condition in Orphanet. They are not a checklist for diagnosing yourself, and they do not all occur in every affected person. Some are examination, imaging or laboratory findings that cannot be recognised at home.

The frequency labels describe how often a finding was reported among people with the condition in the source. They do not give the chance that a person with that symptom has the condition. Definitions below reproduce HPO terminology; they explain the term, not the likely severity in an individual.

Accelerated skeletal maturation · Very frequent (99-80%)

An abnormally increased rate of skeletal maturation. Accelerated skeletal maturation can be diagnosed on the basis of an estimation of the bone age from radiographs of specific bones in the human body.

Ambiguous genitalia · Very frequent (99-80%)

A genital phenotype that is not clearly assignable to a single gender. Ambiguous genitalia can be evaluated using the Prader scale: Prader 0: Normal female external genitalia. Prader 1: Female external genitalia with clitoromegaly. Prader 2: Clitoromegaly with partial labial fusion forming a funnel-shaped urogenital sinus. Prader 3: Increased phallic enlargement. Complete labioscrotal fusion forming a urogenital sinus with a single opening. Prader 4: Complete scrotal fusion with urogenital opening at the base or on the shaft of the phallus. Prader 5: Normal male external genitalia. The diagnosis of ambiguous genitalia is made for Prader 1-4.

Decreased circulating cortisol level · Very frequent (99-80%)

Abnormally reduced concentration of cortisol in the blood.

Decreased circulating renin concentration · Very frequent (99-80%)

An decreased level of renin in the blood.

Elevated circulating 17-hydroxyprogesterone · Very frequent (99-80%)

An increased level of 17-hydroxyprogesterone in the blood. 17-hydroxyprogesterone is an intermediate steroid in the adrenal biosynthetic pathway from cholesterol to cortisol and is the substrate for steroid 21-hydroxylase.

Hypertension · Very frequent (99-80%)

The presence of chronic increased pressure in the systemic arterial system.

Hypokalemia · Very frequent (99-80%)

The concentration of potassium(1+) in the blood circulation is below the lower limit of normal.

Increased circulating androgen concentration · Very frequent (99-80%)

An elevation of the blood concentration of an androgen, that is, of a steroid hormone that controls development and maintenance of masculine characteristics. The androgens include testosterone and Dehydroepiandrosterone.

Other findings in the same source

From: Orphanet

Additional reported features include Increased circulating androstenedione concentration (Very frequent (99-80%)); Increased urinary 11-deoxycorticosterone level (Very frequent (99-80%)); Growth abnormality (Very frequent (99-80%)); Acne (Frequent (79-30%)); Ambiguous genitalia, female (Frequent (79-30%)); Clitoral hypertrophy (Frequent (79-30%)); Hirsutism (Frequent (79-30%)); Hyperpigmentation of the skin (Frequent (79-30%)); Increased circulating ACTH level (Frequent (79-30%)); Irregular menstruation (Frequent (79-30%)). This is a selected summary, not a complete description of the condition.

Which doctor should you see?

The suggested department for discussing Congenital adrenal hyperplasia due to 11-beta-hydroxylase deficiency is Clinical Genetics, with a clinical geneticist as the relevant type of clinician. Paediatrician (children) or physician (adults), with clinical geneticist referral.

Additional services that may be relevant, depending on the findings, include: Nephrology.

This is an editorial referral starting point. The appropriate clinic depends on the person’s age, symptoms, previous diagnosis and local services. The first clinician can decide whether another specialty or a team is needed; a department label does not confirm the diagnosis.

How to prepare for an assessment

Bring a short timeline of the main symptoms: when they first appeared, whether they are constant or episodic, what seems to change them, and how they affect daily activities. Include previous reports, discharge summaries, current medicines and supplements, allergies, and any relevant family history. A dated record is more useful than trying to match every feature in an online article.

Ask the clinician what is already established and what remains uncertain. If a test is suggested, ask what question it answers, what its limitations are and how the result would change the next step. The information here is not an instruction to arrange every possible test. In children, bring growth, developmental and school information if it is relevant to the concern.

• Does the exact genetic or chromosome finding explain the observed features?
• Would a genetic counsellor help the family understand the result?
• Which organ-specific assessments are appropriate for this particular diagnosis?

Treatment discussions and follow-up

The material gathered for this draft does not provide a complete condition-specific treatment pathway for Congenital adrenal hyperplasia due to 11-beta-hydroxylase deficiency. That gap does not mean that treatment is unavailable. A clinician needs to establish the diagnosis and review current guidance before recommending medicines, procedures, rehabilitation or other support.

Before leaving the appointment, clarify the next review date, who will communicate results, and whom to contact if the situation changes. Discuss difficulties with sleep, work, school, mobility, eating or emotional wellbeing when these are relevant. Practical support may require coordination between the treating clinician and other services.

The collected references do not establish a complete prevention or long-term outlook section for this entry. Missing information should not be interpreted as proof that prevention is impossible or that a particular outcome is inevitable. Ask what is known for the exact subtype, stage and personal circumstances, and which uncertainties remain.

When to seek emergency help

Severe breathing difficulty, collapse, new stroke-like symptoms, a seizure that is prolonged or repeated without recovery, uncontrolled major bleeding, or an immediate risk of self-harm require emergency help. In India, call 112 or reach the nearest emergency department. This is a general, non-exhaustive warning list; it is not a condition-specific triage tool.