Corticosteroid-binding globulin deficiency

What it is, symptoms and effects

From: MedlinePlus Genetics, National Library of Medicine

Corticosteroid-binding globulin deficiency is a condition with subtle signs and symptoms, the most frequent being extreme tiredness (fatigue), especially after physical exertion. Many people with this condition have unusually low blood pressure (hypotension). Some affected individuals have a fatty liver or experience chronic pain, particularly in their muscles. These features vary among affected individuals, even those within the same family.

Many people with corticosteroid-binding globulin deficiency have only one or two of these features; others have no signs and symptoms of the disorder and are only diagnosed after a relative is found to be affected.

Some people with corticosteroid-binding globulin deficiency also have a condition called myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). The features of ME/CFS are prolonged fatigue that interferes with daily activities, as well as general symptoms, such as sore throat or headaches.

Causes and biological mechanisms

From: MedlinePlus Genetics, National Library of Medicine

Mutations in the SERPINA6 gene cause corticosteroid-binding globulin deficiency. The SERPINA6 gene provides instructions for making a protein called corticosteroid-binding globulin (CBG), which is primarily produced in the liver. The CBG protein attaches (binds) to a hormone called cortisol. This hormone has numerous functions, such as maintaining blood sugar (glucose) levels, protecting the body from stress, and suppressing inflammation. When cortisol is bound to CBG, the hormone is turned off (inactive). Normally, around 80 to 90 percent of the body's cortisol is bound to CBG. When cortisol is needed in the body, CBG delivers the cortisol where it is needed and releases it, causing cortisol to become active. In this manner, CBG regulates the amount of cortisol that is available for use in the body. The amount of total cortisol in the body consists of both bound (inactive) and unbound (active) cortisol.

SERPINA6 gene mutations often decrease the CBG protein's ability to bind to cortisol; some severe mutations prevent the production of any CBG protein. With less functional CBG to bind cortisol, people with corticosteroid-binding globulin deficiency usually have increased unbound cortisol levels. Typically, the body decreases cortisol production to compensate, resulting in a reduction in total cortisol.

It is unclear how a decrease in CBG protein and total cortisol leads to the signs and symptoms of corticosteroid-binding globulin deficiency. Since the CBG protein is needed to transport cortisol to specific tissues at certain times, it may be that while cortisol is available in the body, the cortisol is not getting to the tissues that require it. A decrease in cortisol may influence widening or narrowing of the blood vessels, contributing to abnormal blood pressure. Some researchers think the features of the disorder may influence each other and that fatigue could be a result of chronic pain rather than a symptom of the disorder itself. There may also be other genetic or environmental factors that influence whether an affected individual is more likely to develop pain or fatigue.

Inheritance and family implications

From: MedlinePlus Genetics, National Library of Medicine

This condition is reported to have an autosomal recessive pattern of inheritance, 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. However, some people with only one SERPINA6 gene mutation may have symptoms such as fatigue or chronic pain. Alternatively, individuals with two SERPINA6 gene mutations may not have any features of the disorder. It is unclear why some people with mutations have features of the disorder and others do not.

How common is it?

From: MedlinePlus Genetics, National Library of Medicine

The prevalence of corticosteroid-binding globulin deficiency is unknown, but it is thought to be a rare disorder. However, because some people with the disorder have mild or no symptoms, it is likely that corticosteroid-binding globulin deficiency is underdiagnosed.

Which doctor should you see?

The suggested department for discussing Corticosteroid-binding globulin deficiency is Endocrinology, with a endocrinologist as the relevant type of clinician. General physician / Family Medicine; paediatrician for children. Referral depends on symptoms.

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

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.

• Which hormone or metabolic finding is important in this case?
• How should test timing and current medicines be taken into account?
• What follow-up would show whether the care plan is working?

Treatment discussions and follow-up

The material gathered for this draft does not provide a complete condition-specific treatment pathway for Corticosteroid-binding globulin 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.