Recognizing cutaneous genetic disorders

Sep 11, 2015, 4:00am

Dermatologists are in a unique position to identify unusual cutaneous findings and help make a genetic diagnosis.

If it swims like a duck, walks like a duck, and quacks like a duck, it’s probably a duck. Except when maybe it’s not. Occasionally, patients present with common complaints that are just enough out of the norm to suggest something from the gene pool, not the duck pond.

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James Treat, M.D., assistant professor of pediatrics and dermatology, University School of Medicine, Children’s Hospital of Philadelphia, always has his radar primed to those little blips that may indicate cutaneous genetic disorders. He presented on the topic in “Pediatric Dermatology 2015” at MauiDerm2015.

Dr. Treat believes that dermatologists are in a unique position to identify unusual cutaneous findings and help make a genetic diagnosis. He’s also quick to point out that the study of genetics is a frenetically expanding field, making it virtually impossible for anyone to memorize all genetic diseases. So he uses a set of four questions that can help alert the clinician that a dermatologic complaint can be associated with a genetic syndrome.

  • Does the patient have other medical problems/two or more unusual findings?

  • Is there a family history of similar findings?

  • Is the child developing normally?

  • Does the child have dysmorphic features?

“If any of these things ring as ‘yes,’ then you might be looking at a genetic disorder,” Dr. Treat says. “There’s no reason that several family members should have unusual dermatologic things going on unless there’s a genetic basis for it or some infectious basis.”

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If a patient has an unusual presentation of typical problems - warts, for example - it warrants further investigation.

“You’ve seen so many normal presentations of warts that when you walk in and you see a patient who has warts covering the entire hand or the entire foot, you can recognize this as unusually exuberant,” he says. “This patient may have an immune disorder which could be genetic. For instance, this could be the initial presentation of a DOCK8 mutation or of WHIM syndrome.  It’s incumbent upon you to ask a few more questions. If you have a ton of warts, and there’s something else going on with the child also, it may be a genetic syndrome,” he adds. “If the diagnosis is in doubt, ask your unusual feature questions.” 

  • Does the patient have other unusual findings?

  • Are there other medical problems that run within the family?

  • Is the patient developing normally?

NEXT: Surfing on the job

 

Surfing on the job

Once a dermatologist suspects there may be something more than meets the eye at work, Dr. Treat suggests a jump into cyberspace.

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“The medical world is now organized into a massive database called Google,” he says. And while “parent blogs are probably not the best way to research things,” he does recommend using electronic resources including peer-reviewed publications or textbooks. “Sites like E-medicine, that’s reviewed. Someone writes it, someone reviews it, and there are references so a reader can delve into the primary literature to confirm the recommendations. That’s a good thing.”

Google images is also a great resource, “but you have to make absolutely certain that whoever put the image in labeled it correctly because there are all sorts of incorrectly labeled images,” Dr. Treat cautions. “But Google images actually draws from a lot of scientific publications now, especially if they’re freely available, which is makes it really useful.”

Google Scholar can be helpful when you’re not sure what you’re trying to find, Dr. Treat says. “You can put in bits of information and it will search like Google does; it will correct your spelling and make suggestions you might not have thought of,” so it’s an excellent resource to help narrow the field. He says OMIM is a great way to look things up “if you know exactly what you’re looking for. You need exact search terms. Try to stick to Scholar or OMIM or another to insure peer-reviewed sources with references.” The onus is on the researcher to investigate cautiously.

Once you believe you have identified a possible condition, Dr. Treat suggests going to www.genetests.org to see if there is a genetic test available for that condition.

READ: Nailing the diagnosis

“The human genome project took many years and cost billions to sequence the entire human genome. You can now get whole exome sequencing for a few thousand dollars or less and it can take as little as a few months,” he says. “Therefore genetic testing is much more available than it was before.”  

Certainly this information must be used judiciously. 

NEXT: Inquiring minds

 

Inquiring minds

One of the really important takeaways, Dr. Treat says, is that dermatologists visually observe subtle signs in the skin. "So your job as a dermatologist is to correctly describe something, not to have memorized every genetic disease on the planet, because it’s impossible,” he advises. “Then use your resources to figure out how that strange thing you’re seeing could play a role or be associated with other pathologies…. The geneticist will ask you to describe correctly what you see on the skin…. Once you describe a couple of unusual things happening with one patient, you or they can then look them up and figure out what the person probably has.”

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Capillary malformation - arteriovenous Malformation syndrome (CM-AVM) - is an example of a genetic condition associated with multiple capillary malformations that are inherited autosomal dominantly, Dr. Treat says.

“The capillary malformations in CM-AVM may look like café au laits but are red-purple. And because some people with these CMs have AVMs internally, early screening for these AVMs can be life-saving. You can do something to prevent a catastrophic event if you can recognize the skin findings,” he says.

Pediatricians and pediatric dermatologists are gateways to the rest of the patients’ care, he says, and can refer patients toward the right specialists and/or additional screening.

“I think many general dermatologists think genodermatoses are things they either are not going to see or are so rare as to be irrelevant. Most kids with these common skin complaints don’t have genetic problems, but for the rare child who might, they may present to the dermatologist first because of the warts or capillary malformation for example,” he says. “So you have to have your radar up for when it might be something unusual,” then you can start to ask the basic screening questions. “If they’re totally well and they just have a random finding, then it’s probably just random. If they’re not totally well and they have a random finding, it may be something else.”

Most patients don’t usually present to a geneticist asking if they have genetic disorders, Dr. Treat notes. “Much more commonly, they show up to us and we have to be able to realize that they might,” he says. “If you have someone who has two unusual things going on, they may just have two unusual things going on. But they might have a genetic disorder. And if they do have a genetic disorder, you are really in a place where you can help figure out what it is and test for it.”

So if the duck in the office walks, swims, and quacks like a duck, but something seems fowl, take a closer look and ask some questions. There just might be something lurking in the gene pool.