This is a multisystem disorder that can affect the development of any of the body’s organs but particularly the skin, eyes, hands and the feet. This disorder causes the nails, hair, teeth and the glands to develop abnormally. In addition, it can also affect the gastrointestinal, neurological, genitourinary and cardiovascular systems. As this is a rare condition, only 300 cases are reported and the majority of these are women.
Symptoms
The skin abnormalities are evident at the birth of the infant and this includes yellowish-pink nodules under the skin, streaks of thin skin, patches where top skin layer may be absent and the presence of a cluster of veins. The skin abnormality presents infections, itching and pain. Wart- like growths known as papillomas is generally not apparent at birth but can develop later in life. This can appear in the gums, tongue, genitalia, lips and the anus. The soles of the feet and the hands may have an overgrowth of tissue. They also tend to have sparse or brittle hair on their scalp. The eye abnormalities can impair the vision or cause blindness and can include clouding of the cornea, drooping eyelids, rapid movement of the eyes, more than a single color within the iris and crossed eyes. The distinctive facial features include pointed chin, notched nostrils, facial asymmetry, cleft lip and cleft palate. In addition, they may have abnormalities of the kidneys and the gastrointestinal system.
Causes
Focal dermal hypoplasia develops as the result of a mutation in the gene PORCN which is essential for delivering the instruction to produce a protein that modifies other proteins. This is called the Wnt proteins which are important for the chemical signaling pathways that regulate the development of various structures such as the skin and bones before the birth of the child. The genetic mutation results in the Wnt protein unable to leave the cell and hence they cannot be a part of the chemical signaling process for the body’s various normal development. This is inherited in an X-linked dominant pattern where the defective gene is located in one of the sex chromosomes.
Diagnosis
The diagnosis of focal dermal hypoplasia is based on the clinical findings and the characteristic signs that are evident at the birth of the infant. In order to evaluate the extent of abnormalities and to determine the treatment, various diagnostic tests may be necessary. This can consist of chest x-ray, abdominal MRI, ultrasound, medical genetics consultation and hearing evaluation. In addition, the DNA testing can detect the mutation in the gene that is responsible for causing this condition.
Treatment
As there is no cure for this condition, the treatment is directed at the various symptoms. This can include dermatological creams to help relieve the skin problems and to prevent the development of any skin infections. Dentures and hearing aids may also be needed. In addition, limb deformities may require occupational therapy or surgery. In the case of problems with swallowing, surgical intervention may be required.
References
https://rarediseases.org/rare-diseases/focal-dermal-hypoplasia/
https://ghr.nlm.nih.gov/condition/focal-dermal-hypoplasia#inheritance
http://www.cafamily.org.uk/medical-information/conditions/f/focal-dermal-hypoplasia/
http://www.dermnetnz.org/topics/focal-dermal-hypoplasia/
