In Rare Case, DEB Linked to Newborn’s Toe Deformities

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by Marta Figueiredo PhD |

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Dominant dystrophic epidermolysis bullosa (DEB) may lead to congenital deformities such as disproportionately short great (big) toes, according to a case report.

In this rare case, the newborn also lacked skin in the lower part of both legs (a more common symptom of DEB), and with appropriate treatment his wounds healed well in the following months.

While the underlying causes of the congenital toe deformities remain unclear, this case highlights the importance of having a multidisciplinary team to manage DEB and other forms of epidermolysis bullosa, the researchers noted.

The case study, “Dominant dystrophic epidermolysis bullosa with congenital absence of skin and brachydactyly of the great toes,” was published in the journal Pediatric Dermatology.

DEB is one of the major forms of epidermolysis bullosa, characterized by blisters that often leave scars when they heal or areas of congenital absence of the skin (CAS). It is caused by mutations in the COL7A1 gene, which provides the instructions to produce type VII collagen, key for the adhesion between layers of skin.

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In dominant DEB, inheriting only one copy of the mutated COL7A1 gene is sufficient to cause the disease. In recessive DEB, a child has to inherit two mutated copies (one from the mother, and the other from the father) to develop full-blown disease.

Contrary to its recessive, more severe form, dominant DEB is associated with mostly benign blistering that often is limited to the extremities and reduced with age, and less common non-skin manifestations.

In agreement, musculoskeletal complications — that can affect bones, muscles, tendons, ligaments and soft tissues — particularly those present at birth, have been reported rarely in dominant DEB.

Now, researchers at the Oregon Health & Science University described a rare case of dominant DEB associated with CAS and congenital toe deformities in a baby boy.

The boy was the first child of a 28-year-old woman whose pregnancy was notable only due to detectable poor growth of the fetus. No history of skin disorders was reported in the family.

At 1-day-old, he was taken to an external neonatal intensive care unit and showing extensive skin erosion on both legs, which was managed with emollients and non-adhesive protective dressings.

The boy then was taken to the researchers’ hospital for follow-up, where lack of skin was detected in both legs extending to the feet. His leg wounds were mostly clean, and he appeared well, with no fever or other signs of infection.

The boy’s wounds “healed well in the following months, with occasional new erosions and blisters,” the researchers wrote, adding that he also experienced intermittent skin irritation over his scarring, which was managed with hydrocortisone ointment and emollients.

Genetic testing revealed a disease-causing mutation (c.6007 G>A) in only one copy of the COL7A1 gene, consistent with dominant DEB. The same mutation was found in the boy’s father, who had subtle skin changes, including darker patches of skin in the lower legs. It was unclear if the father experienced blistering at birth, said the researchers.

The parents noted the boy also had disproportionally shorter great toes since birth, a feature more pronounced on the left side. This became a concern when the boy began to walk and seemed to do so on his toes, prompting an evaluation by orthopedic surgery at 11 months.

Radiographic imaging confirmed bone shortening on both great toes, particularly pronounced in the left, and showed mildly shorter bones in the other toes. The boy also had toenail abnormalities.

“Few cases with similar findings have been described in patients with DEB and none with genetic confirmation of [dominant DEB],” the researchers wrote.

“In contrast to acquired musculoskeletal abnormalities likely caused by recurrent blistering, a mechanism to explain the association between congenital musculoskeletal abnormalities, such as brachydactyly, has yet to be proposed,” the team added. Brachydactyly is the medical term for shortening of the fingers and toes due to unusually short bones.

While it is unlikely that the boy “will experience disability due to his foot deformities,” this case “highlights the importance of multidisciplinary care management in many forms of EB, including orthopedics assessment,” the researchers concluded.