3-beta-hydroxysteroid dehydrogenase deficiency

What it is, symptoms and effects

From: MedlinePlus Genetics, National Library of Medicine

3-beta (β)-hydroxysteroid dehydrogenase (HSD) deficiency is an inherited disorder that affects hormone-producing glands including the gonads (ovaries in females and testes in males) and the adrenal glands. The gonads direct sexual development before birth and during puberty. The adrenal glands, which are located on top of the kidneys, regulate the production of certain hormones and control salt levels in the body. People with 3β-HSD deficiency lack many of the hormones that are made in these glands. 3β-HSD deficiency is one of a group of disorders known as congenital adrenal hyperplasias that impair hormone production and disrupt sexual development and maturation.

There are three types of 3β-HSD deficiency: the salt-wasting, non-salt-wasting, and non-classic types. In the salt-wasting type, hormone production is extremely low. Individuals with this type lose large amounts of sodium in their urine, which can be life-threatening. Individuals affected with the salt-wasting type are usually diagnosed soon after birth due to complications related to a lack of salt reabsorption, including dehydration, poor feeding, and vomiting. People with the non-salt-wasting type of 3β-HSD deficiency produce enough hormone to allow sodium reabsorption in the kidneys. Individuals with the non-classic type have the mildest symptoms and do not experience salt wasting.

In males with any type of 3β-HSD deficiency, problems with male sex hormones lead to abnormalities of the external genitalia. These abnormalities range from having the opening of the urethra on the underside of the penis (hypospadias) to having external genitalia that do not look clearly male or female. The severity of the genital abnormality does not consistently depend on the type of the condition. Because of the hormone dysfunction in the testes, males with 3β-HSD deficiency are frequently unable to have biological children (infertile).

Females with 3β-HSD deficiency may have slight abnormalities of the external genitalia at birth. Females affected with the non-salt-wasting or non-classic types are typically not diagnosed until mid-childhood or puberty, when they may experience irregular menstruation, premature pubic hair growth, and excessive body hair growth (hirsutism). Females with 3β-HSD deficiency have difficulty conceiving a child (impaired fertility).

Causes and biological mechanisms

From: MedlinePlus Genetics, National Library of Medicine

Mutations in the HSD3B2 gene cause 3β-HSD deficiency. The HSD3B2 gene provides instructions for making the 3β-HSD enzyme. This enzyme is found in the gonads and adrenal glands. The 3β-HSD enzyme is involved in the production of many hormones, including cortisol, aldosterone, androgens, and estrogen. Cortisol has numerous functions such as maintaining energy and blood sugar (glucose) levels, protecting the body from stress, and suppressing inflammation. Aldosterone is sometimes called the salt-retaining hormone because it regulates the amount of salt retained by the kidney. The retention of salt affects fluid levels and blood pressure. Androgens and estrogen are essential for normal sexual development and reproduction.

3β-HSD deficiency is caused by a deficiency (shortage) of the 3β-HSD enzyme. The amount of functional 3β-HSD enzyme determines whether a person will have the salt-wasting or non-salt-wasting type of the disorder. Individuals with the salt-wasting type have HSD3B2 gene mutations that result in the production of very little or no enzyme. People with the non-salt-wasting type of this condition have HSD3B2 gene mutations that allow the production of some functional enzyme, although in reduced amounts.

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

The exact prevalence of 3β-HSD deficiency is unknown. At least 60 affected individuals have been reported.

Which doctor should you see?

The suggested department for discussing 3-beta-hydroxysteroid dehydrogenase deficiency is Clinical Genetics, with a clinical geneticist as the relevant type of clinician. Paediatrician (children) or physician (adults), with clinical geneticist referral.

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 3-beta-hydroxysteroid dehydrogenase 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.