Not much is known about the causes of autosomal recessive lamellar ichthyosis. However, mutations have been found in the enzyme transglutaminase. Transglutaminase is responsible for the formation of the cell membrane in the stratum corneum cells. In the meantime, a second gene locus has been found, but what is encoded at this site is currently unknown. In addition to these two gene loci, there must be at least a third site in the genome that leads to ichthyosis when defective.
Ichthyosis: genetic defect as cause
So far, it appears that there is no correlation between the severity of ichthyosis and the different gene loci. To find out whether patients actually lack this important enzyme, a small skin sample is taken and deep-frozen to subsequently measure the activity of the enzyme using a novel biochemical test developed by the Münster research group.
The scientists were able to detect a mutation in the transglutaminase 1 gene in the “collodion baby,” for example. The development of new therapeutic strategies for the severe forms of ichthyosis is aimed at genetically engineering the missing enzymes in bacteria or yeast cultures and introducing them into ointments. If this approach proves successful, it would indeed be a breakthrough towards a causal treatment.
Professor Dr. Heiko Traupe, dermatologist and spokesman of the “Network for Ichthyoses and Related Cornification Disorders” (NIRK), however, does not want to raise false hopes too early. Experimental work is still needed first, he says. “In five years,” he estimates, “we will be ready to conduct the first clinical trials in humans.”
Ichthyosis: an isolated life as a result
“Not only do sufferers literally feel uncomfortable in their skin,” Professor Traupe points out, “they usually also have great difficulty accepting themselves. Many live extremely secluded lives because they fear the reaction of their environment to their external appearance. In addition, they require extreme care. To treat the extremely dry and horny skin all over the body, from which dandruff constantly trickles, the patients usually spend at least an hour in the tub every day for the rest of their lives.”
Heiko Traupe is one of the few scientists in Germany who are intensively involved in the scientific and clinical treatment of ichthyosis. Patients from all over Germany come to the special consultation he directs at the Dermatology Department of Münster University Hospital, which, along with clinics in Cologne, Marburg and Bad Salzschlierf, is one of only four specially designated contact points for ichthyosis patients in Germany. The NIRK focuses on the particularly severe variants of ichthyosis, which statistically affect only two out of 100,000 patients and thus about 1,600 to 2,000 patients nationwide.
Lamellar ichthyosis
“Marc was a premature baby. His skin resembled oiled parchment. The yellowish-brownish skin was translucent and gradually cracked. The skin underneath was reddish and scaly.” Marc’s parents learned their son had congenital lamellar ichthyosis, medically called “autosomal recessive lamellar ichthyosis.” Babies with these symptoms are also called collodion babies (Greek lat. “glue-like”). Sometimes the skin is completely reddened, while in other affected individuals there is no redness.
The size and color of the scaling varies greatly. In many there is a rather fine and light brown scaling, but in others there may be a much thicker, plate-like and often very dark keratinization. The scales always consist of thin layers of cells that lie on top of each other like lamellae; hence the name “lamellar ichthyosis”.
Since the skin is very dry, the lower eyelids may be pulled down, a so-called ectropion. Palms and soles are often furrowed by pronounced lines and show increased horniness. Babies with the collodion membrane are high-risk patients who receive intensive medical monitoring. Their skin has little ability to retain water due to the genetically altered structure of the horny layer. So the infants lose fluid very quickly and also heat.
