Introduction

Getting a diagnosis for a rare skin condition like epidermolytic ichthyosis (EI) can feel overwhelming, especially if you’re not sure what the process involves. This article breaks down the key diagnostic tools used to identify EI. Whether you’re a parent, patient, or simply curious, you’ll learn what to expect during diagnosis and why each step plays an important role in getting the right answers.

What is epidermolytic ichthyosis? 

EI is a rare genetic condition distinguished by a range of blistering and scaling of the skin, affecting one in every 200,000 individuals. The symptoms usually appear at birth or soon after and can worsen over time, ranging from mild blistering caused by friction to severe skin erosions or thick, wart-like scaling across the body. Individuals may also experience hair and nail abnormalities, decreased sweating, and callus formation on the palms or soles, known as palmoplantar keratoderma. Microscopic examination of the skin may reveal mid-epidermal splits and thickening of the skin (hyperkeratosis). Currently, treatment focusses on managing specific symptoms and preventing skin infections, involving topical therapies, medications, and antiseptic washes. Cosmetic issues and unpleasant odours are also associated with EI and can lead to significant stress and psychological challenges for those who are affected.¹ 

The importance of an accurate diagnosis of EI

Accurate diagnosis of EI is vital to ensure proper education and counselling of parents, as well as for treatment to ensure peace of mind for the individual and their family. Genetic counselling and prenatal diagnosis can also be offered. 

Understanding how EI is diagnosed is just the first step. In the sections ahead, we’ll look at why early and accurate diagnosis matters, what the testing process is like, and how these tools guide treatment decisions.

The two primary diagnostic tools used for EI

Genetic testing is one of the fundamental tools used in the confirmation of EI by identifying mutations in the genes that cause skin disorders. Genetic testing provides a definitive diagnosis and helps with family planning and understanding inheritance risks.

A skin biopsy is also vital, in which a skin sample is examined under a microscope. In EI, the biopsy often reveals abnormal changes to the thin outer layer of the skin (the epidermis). While a biopsy can strongly suggest EI, to get a complete picture, it is combined with genetic testing.

Why diagnosis matters

EI can resemble other skin conditions, especially in newborns. The correct diagnosis helps to guide treatment and skin care, inform families about inheritance patterns, and plan for long-term management of the condition. 

In today’s society, confirming a molecular diagnosis is increasingly practical in patients with EI and is necessary for ensuring correct genetic advice and information about prognosis and treatment. This is especially important for young adults with EI, as the condition can sometimes affect pregnancy or pose risks to newborns (perinatal morbidity).²

The two main diagnostic tools

Genetic testing

What is genetic testing? 

Genetic testing looks at a person’s DNA to find mutations in specific genes. For EI, DNA is tested for harmful variants in the KRT1 and KRT10 genes to confirm a diagnosis.¹

In the past, doctors have mainly relied on physical symptoms, family history, and skin samples for the diagnosis of EI. However, in the last 10 years, genetic testing has transformed the way EI is diagnosed. These tests can now quickly and accurately identify the exact genetic cause, which helps doctors choose the best treatment, give patients an idea of what to expect, and offer advice to families. The most common method used today is called next-generation sequencing (NGS), a powerful technology that can analyse many genes at once, making genetic diagnosis much faster and more precise than ever before.³

How genetic testing works:

A simple blood or saliva sample is collected, and laboratory experts analyse the DNA for EI-related changes.

What genetic testing shows: 

As EI is caused by harmful variants in the KRT1 or KRT10 gene, resulting in incorrect expression of the structural proteins keratin 1 and keratin 10 found in epidermal cells, the malfunctioning proteins lead to barrier abnormalities that can lead to epidermal inflammation, causing the various symptoms seen in the disease. Genetic testing confirms the presence of EI by identifying the precise mutation, which is important for family planning and understanding the severity of the disease.¹

Benefits and limitations of genetic testing:

Benefits:

Having a genetic diagnosis is more accurate than a clinical diagnosis. The process is non-invasive, and clarifies inheritance as you know the exact mutation causing EI. In the next 10-20 years, treatments may likely become highly personalized, targeting the specific gene involved, which could make genetic diagnosis essential for participation in trials for new treatments.⁴

Limitations:

The few limitations of genetic testing are its cost, limited availability in some areas, and the time it can take to receive results.

Skin biopsy

What is a skin biopsy?

Doctors can often diagnose EI very soon after birth by taking a small skin sample (a biopsy), and when examined under a microscope, the structure of the skin cells shows a very unique pattern, allowing for a quick and accurate diagnosis of EI. The mutations in genes that produce proteins called keratins are prevented from helping to build a framework inside skin cells that keeps them strong and connected. The support structures inside the skin cells don’t form properly, and as a result, the cells become fragile and don’t stick together like they should. This can lead to the formation of blisters, especially in the outermost layer of the skin. The thick, scaly skin often seen in EI is actually the body’s way of trying to repair the skin and protect it in response to the skin’s weakened barrier, and it aims to compensate for the damage caused by the faulty keratin.⁵

How is a skin biopsy performed?

A skin biopsy is often performed under local anaesthesia to numb the skin, and a tool is then used to take a sample of tissue, which is sent to a laboratory to examine the structure of skin cells. 

What does a skin biopsy show?

When doctors examine a skin sample under a microscope, some common features are seen to strongly suggest the presence of EI, including a thickened outer layer of skin (hyperkeratosis), a thickened layer of grainy cells, and larger, coarser clumps of material called keratohyaline granules. Often, there is also damage in the upper layer of the skin cells. Doctors may further see signs of premature skin cell death (called dyskeratosis), which can vary in how much is present.

If these changes are seen throughout the entire sample, it suggests that the condition affects the whole body. However, if the abnormal areas are patchy with sections of healthy skin in between, the patient may have a mosaic form of the disease, meaning the condition only affects certain areas of the body.⁶

Benefits and limitations of a skin biopsy:

Benefits:

Skin biopsies are widely available and can provide quick visual confirmation of the condition. 

Limitations

It is a minor procedure; therefore, there is a small risk of infection or scarring. A skin biopsy may not always be able to distinguish EI from similar conditions.

Sometimes, both are used together - a biopsy can give quick initial clues, while genetic testing confirms the diagnosis and offers more detailed information.⁷

Looking ahead 

Genetic testing is becoming more accessible and may eventually replace biopsies as the first-line tool. Advances in research may lead to better targeted therapies.

FAQs

Is genetic testing always necessary for diagnosing EI?

While a skin biopsy can suggest EI, genetic testing is the most reliable method for a definitive diagnosis.

How long does it take to get genetic test results?

It can take several weeks, depending on the lab and the type of genetic panel ordered.

Does a skin biopsy hurt?

A biopsy involves taking a small piece of skin under local anaesthesia, so it may cause mild discomfort but is generally well tolerated.

Can these tests also predict how severe the condition will be?

Genetic testing can indicate the mutation type, but the severity of EI can still vary between individuals.

Summary 

Ultimately, the diagnosis of EI is reliant on a skin biopsy and genetic testing, often used together. A correct diagnosis is vital in helping to empower families with knowledge about the condition and treatment options to improve morale and reduce any discomfort. Although EI is rare, modern tools make detection and management more reliable than ever.