Ichthyosis: Rare Genetic Skin Disorder

Updated March 21, 2019

This article was scientifically reviewed by YourDNA Staff

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A list of references is also included at the bottom of this article.

Ichthyosis, also known as "fish scale disease," is a rare skin disorder that is normally passed down from a parent to a child, though it can occur spontaneously as well.

Knowing about the condition can help you seek proper treatment and YourDNA strives to provide you with comprehensive information about the disease and its treatment in one single, helpful location.

What's in this Guide?

Disclaimer: Before You Read

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Quick Overview

A rare, but mostly harmless condition, ichthyosis affects around 16,000 babies per year 1, with approximately 300 to 400 of those cases being moderate to serious in nature.

Harlequin ichthyosis is the most serious condition and can cause death in newborns who do not receive proper treatment. It's also the rarest form affecting around 7 infants 2 in the United States each year.

Ichthyosis is a lifelong condition with no cure. However, medical treatment makes the disease manageable, and many times the condition eases up during the adult years.

It's also possible to find ichthyosis in dogs 3, as it's not strictly a human-related disease.

What Is Ichthyosis?

Ichthyosis is a series of skin disorders that result in an unsightly build-up of skin cells that look like fish scales, hence its nickname.

The condition occurs in one of two ways: when the body is producing too much skin for it to shed normally or when the body produces enough skin but the shedding process is too slow. Common symptoms include skin dryness and scaling.

There are a variety of different types of ichthyosis, though they're broken down into two categories: inherited and acquired 4. Inherited versions are passed down genetically, through a mutation that passes from parent to child.

Acquired conditions are a little trickier because they often come on without any prior warning and occur spontaneously.

Inherited Ichthyosis

There are a few different types of inherited ichthyosis, but the most commonly talked about are ichthyosis vulgaris, x-linked and Harlequin. They differ in many ways, but particularly in the severity of the condition and the required level of treatment.

Inherited Ichthyosis Vulgaris

This is the most common type of inherited ichthyosis 5. It's very treatable and sometimes it's evident right at birth, though it's not uncommon to see the symptoms appear at some point within the first year of a person's life.

X-Linked Ichthyosis

The ichthyosis panel x-linked recessive disorder is usually only present in males, though females can be unaffected carriers 6. The scales are darker and more pronounced, typically appearing on the trunk and back of the neck areas.

Harlequin Ichthyosis

Harlequin ichthyosis is a genetic skin disorder that presents differently than ichthyosis vulgaris in a drastic way. Where symptoms normally present within a few days or weeks, sometimes up to a year later in ichthyosis vulgaris, Harlequin appears immediately at birth.

The baby is born covered in thick, hard skin that's almost impenetrable and makes the infant look severely deformed. The skin pulls the eyes and mouth back to reveal the inner red linings and also pins the ears to the head 7, making it look as though the baby has no ears.

The prognosis for Harlequin used to be dire, but with modern medicine, most babies will survive when they receive immediate medical attention, which may require a longer hospital stay.

Acquired Ichthyosis Vulgaris

Acquired versions of the skin conditions vary in severity, though they're often manageable with simple topical creams. Some come on as a result of medications while others present as a secondary medical condition.

These types of ichthyosis often disappear when the primary condition is addressed.

Is Ichthyosis Hereditary?

In some cases, yes ichthyosis is hereditary. However, not everyone who carries the gene mutation will end up with the condition.

Some people just pass it onto their children, where it may or may not present, and they're known as carriers. Even parents who don't have the gene mutation associated with ichthyosis can have children with the mutation if it happens spontaneously within an egg, sperm or when the two meet.

What Causes Ichthyosis?

There are two different types of ichthyosis: inherited and acquired. The causes of the two conditions are different, as demonstrated below.

Inherited Ichthyosis

Inherited ichthyosis occurs when the gene mutation is passed down the bloodline. One or both parents who are carriers, or who have the condition themselves can pass it on. Inherited ichthyosis can and does present during infancy, though it may present later in life, which is different than acquired ichthyosis.

Acquired Ichthyosis

Acquired ichthyosis occurs during adulthood and this type has doctors perplexed because there is no direct known cause. However, there are a variety of other diseases that often go hand in hand with the diagnosis of acquired ichthyosis, including:

  • Kidney disease
  • Cancer
  • Sarcoidosis
  • Underactive thyroid
  • HIV

Some medicines might trigger the condition, as well, a side effect of sorts. Those medications include cancer drugs, protease inhibitors used to treat HIV and nicotinic acid.

Diagnosis of Ichthyosis

Diagnosing the genetic skin disorder typically requires a DNA test to identify the gene mutation, but doctors will probably do additional testing as well.

This is to rule out any other possible medical conditions that could be responsible for the skin abnormalities.

How Do You Diagnose Ichthyosis?

The most common way that doctors diagnose ichthyosis is by simply examining the skin and the way it appears. Skin dryness and scaling don't always mean that you have the condition, so it's important for your physician to rule out other potential causes.

When other possibilities have been ruled out, the diagnosis of ichthyosis is made. However, sometimes it's glaringly obvious and no further testing will be done before treatment is administered.

How Do Doctors Test for Ichthyosis?

The most common way of testing for ichthyosis before ordering a DNA test is to do a skin biopsy. The skin is then viewed under a microscope for classic patterns, typically in a diamond shape that's associated with ichthyosis.

Ichthyosis and Genetics

The most common form of ichthyosis is heritable, through a mutation on chromosome 1q21 8. The mutation is associated with the protein filaggrin.

When the body doesn't produce enough filaggrin, the skin fails to shed as it's supposed to. X-linked recessive is tied to the STS gene located on the X chromosome.

In x-linked recessive, the skin produces at a normal rate, but the shedding process is too slow which results in the build-up on the skin's surface.

Harlequin ichthyosis, on the other hand, is due to a mutation in the ABCA12 gene that occurs on chromosome 2q34. This mutation affects the ATP-binding cassette transporter protein, which is responsible for the transportation of fat across skin cells to help prevent water loss.

Genetic Tests for Ichthyosis — Are They Available?

Yes, you can have genetic testing done to determine if you have ichthyosis and which type it is. The presence of a gene mutation indicates that it's heritable, while the lack of a mutation signifies that it's an acquired version.

DNA Testing to Spot or Detect Ichthyosis Early

There is DNA testing to help detect the presence of ichthyosis early, even before pregnancy as discussed in further detail below. Most children who have the disorder show symptoms at a very young age.

Parents who notice that their children have thicker or drier skin than normal should consult with their pediatrician. A referral to a pediatric dermatologist can help with treatment.

DNA Tests Currently Available for Ichthyosis Include:

There are currently multiple DNA panels available for ichthyoses, which is the class of all the skin disorders that ichthyosis falls under.

The most reliable DNA panels come from a laboratory, ordered by a qualified physician. There are some at-home tests you can order for ichthyosis in dogs, but for humans, there are currently very few, if any, on the market.

DNA Testing for Ichthyosis: Strengths and Limitations

One of the strengths of DNA testing is that it can help doctors pinpoint the exact type of ichthyosis a person has if it's an inheritable form.

This information is useful in helping doctors to eliminate the possibility of an underlying disease causing the skin condition. Expectant parents who undergo CVS, for example, can be prepared before the baby's born.

There are also limitations on the DNA testing. While it's beneficial in determining the exact type of skin disorder a person has, it doesn't help with the prognosis. The treatment is likely to be the same and include a variety of topicals, though supplements may also be recommended.

Testing for Ichthyosis on a Pregnancy or Before a Pregnancy is Achieved

Testing for ichthyosis during pregnancy versus before pregnancy requires two different types of testing. During pregnancy, the fetus can be tested using amniocentesis and chorionic villus sampling, also known as CVS 9.

This poses a small risk to the pregnancy but can help determine if there is a mutation in the ABCA12 gene.

Before pregnancy, if there's a family history of ichthyosis, couples may want to know what the risk is of passing it onto an infant. Genetic counseling can help with understanding the findings of the DNA sampling, which is usually collected with a small blood sample or through a buccal swab of both partners.

Couples going through in-vitro fertilization can actually request a pre-implantation diagnosis, to detect any mutations before the fertilized egg is implanted.

Finding Out What Type of Ichthyosis You Have

Since the condition doesn't always present in infancy, if symptoms occur later in life, doctors will likely want to test to determine which type of ichthyosis you have.

Pinpointing the exact gene and type requires DNA sampling. If there is no mutation present in the genes and chromosomes associated with the disorder, doctors can reasonably assume that it's an acquired variant.

What Are the Chances That I Will Pass Ichthyosis on to My Child?

The chances of passing on ichthyosis to your child depend on the variations of the genes that he or she receives from both parents.

If both parents are carriers, there's a 25 percent chance of the child having ichthyosis. However, if both are carriers the child has a 50 percent chance of also being a carrier. The risks decrease if only one parent is a carrier.

Who Does Ichthyosis Typically Affect?

Ichthyosis does not discriminate against anyone regardless of gender, race or age.

While it typically shows up in infancy, it's very possible for symptoms to present later in life. Men and women are both equally susceptible.

Does Ichthyosis Occur in Children?

Yes, the most common form affects mostly infants who usually develop symptoms within the first few days or weeks of life.

Ichthyosis Treatment Options

Is Ichthyosis Treatable?

Yes, the skin condition is very treatable, however, it's not curable. What doctors aim to do after diagnosing the condition is make it manageable, and this typically includes using a special moisturizing cream that helps the skin shed its dead cells. These medicated creams usually include one or more of the following:

  • Urea
  • Salicylic acid
  • Lactic acid
  • Glycolic acid

Doctors may also recommend at-home treatments that don't involve medications, such as emollients to keep the skin moisturized and exfoliants to help clear the skin up. Soaking in hot baths to open up the pores and then applying lotions, body oils or even petroleum jellies is often very helpful.

The Prognosis for Ichthyosis

The prognosis for ichthyosis is currently favorable because most forms of the disorder are treatable. While there's no cure, most people live very functional lives with treatment that keeps them comfortable.

For the more severe forms, including Harlequin ichthyosis, the prognosis is getting better with medical advances and there are many Harlequin ichthyosis survivors where it used to be nearly 100 percent fatal. However, because of the thickness of the skin and because it does affect the face, it's not uncommon for babies to have feeding difficulties, which can hinder growth and development.

Sometimes, the effects on a person with ichthyosis aren't physical, but mental and lead to psychological issues such as insecurity and low self-esteem.

Does Ichthyosis Go Away?

The answer to this depends on what type of ichthyosis a person has. Inheritable forms never go away; they're lifelong afflictions. However, acquired versions of ichthyosis will typically go away when the primary cause is addressed.

Is There a Cure for Ichthyosis?

No, there is no cure, but there are plenty of ways to manage the disorder. Perhaps in the future through clinical trials, researchers will develop one.

What Are Ichthyosis Care Options?

Currently, care options include the aforementioned creams and other emollients, but sometimes there are secondary bacterial infections that occur when the skin can't breathe. In this case, doctors will often prescribe topical or oral antibiotics.

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Referenced Sources

  1. New Study Estimates Incidence of Moderate to Severe Ichthyosis.
    The Foundation for Ichthyosis & Related Skin Types, Inc.®.
  2. Ichthyosis, Harlequin Type.
    National Organization for Rare Disorders (NORD).
  3. Canine ichthyosis and related disorders of cornification in small animals. Vet Clin North Am Small Anim Pract.
    Elizabeth A. Mauldin, DVM, Diplomate ACVP & ACVD. Jan 2013.
  4. Ichthyosis.
    DiGiovanna, J.J. & Robinson-Bostom, L. Am J Clin Dermatol. 2003. Published Online 21 August 2012.
  5. Ichthyosis.
    DiGiovanna, J.J. & Robinson-Bostom, L. Am J Clin Dermatol. 2003. Published Online 21 August 2012.
  6. X-Linked Ichthyosis.
    Ichthyosis Support Group (ISG).
  7. Improved Management of Harlequin Ichthyosis With Advances in Neonatal Intensive Care.
    Jaimie B Glick, Brittany G Craiglow, Keith A Choate, Hugo Kato, Robert E Fleming, Elaine Siegfried, Sharon A Glick. American Academy of Pediatrics. Published online January 02, 2017.
  8. Inherited Nonsyndromic Ichthyoses: An Update on Pathophysiology, Diagnosis and Treatment.
    Anders Vahlquist, Judith Fischer, and Hans Törmä. Am J Clin Dermatol. Published online 16 Aug 2017.
  9. Intrauterine Diagnosis of Genodermatoses.
    Yuval Ramot. Published Online 03 September 2013.