What is focal dermal hypoplasia?
Focal dermal hypoplasia is a genetically inherited disorder that can affect the development of many different organ systems and was first described by Goltz in 1962. It presents with characteristic abnormalities of the skin, eyes and teeth and may also have effects on the skeletal, gastrointestinal, genitourinary, neurological and cardiovascular systems.
It is a rare condition with fewer than 300 cases reported, most of whom are female.
The name is actually misleading, as thinning of tissues is not confined to the dermis but also involves the epidermis and subcutaneous tissue.
How do you get focal dermal hypoplasia?
Focal dermal hypoplasia is genetically inherited in an X-linked dominant fashion. It is caused by abnormalities of the PORCN gene on the X chromosome, and most often these arise in the embryo and are not inherited from a parent. The X chromosome is one of the sex chromosomes: females are XX, males are XY. Females with one abnormal X chromosome are affected by FDH, but most males embryos with the abnormal gene do not survive.
Focal dermal hypoplasia can affect almost any organ in the body. As with some other X-linked dominant conditions the skin manifestations follow developmental lines known as Blaschko lines.
Genetics of Focal dermal hypoplasia*
*Image courtesy Genetics 4 Medics
What are the effects of focal dermal hypoplasia?
Focal dermal hypoplasia can have a wide range of effects on a variety of organ systems and the severity of the condition can vary greatly between individuals depending on the number of organs involved and the nature of the abnormalities.
- Linear hypoplastic (thinned) streaks which follow the lines of Blaschko
- Fat nodules and fat herniation
- Telangiectasia (visible superficial blood vessels)
- Verrucoid papillomas (warty growths)
- Pyogenic granuloma-like lesions
- Alopecia (thinning, balding, hair loss), brittle/sparse hair
- Nail abnormalities
- Palmar and plantar hyperkeratosis (thickened skin on hands and feet)
- Aplasia cutis congenita (localised total loss of skin)
- Hyperhidrosis (excessive sweating)
- Structural eye abnormalities: microphthamia (small eye), anophthalmia (missing eye)
- Displaced lens
- Choroidoretinal coloboma (missing retina and choroid)
- Optic nerve atrophy (lack of nerve supply to the eye)
- Blocked lacrimal (tear) duct
- Dental abnormalities: hypoplastic (small) teeth, abnormal enamel
- Microcephaly (small head), unilateral facial microsomia (underdeveloped face)
- Cleft lip and palate
- Low set ears
- Hand and foot abnormalities: ectrodactyly (lobster claw), brachydactyly (short fingers), oligodactyly (missing fingers), syndactyly (joined-up fingers)
- Abnormal vertebrae, bifid (double) or fused ribs, small collarbone
- Striated (striped) bones on X-ray
- Structural kidney abnormalities: renal agenesis (missing kidney), horseshoe kidney, hydronephrosis (swollen kidney), bifid (split) ureter
- Bladder exstrophy (inside-out bladder)
- Oomphalocoele (abdominal contents outside the belly)
- Intestinal malrotation (twisted bowel)
- Anteriorly displaced anus
- Severe gastro-oesophageal reflux
- Congenital heart disease
- Structural abnormalities of the cental nervous system: meningomyelocoele (spina bifida), hydrocephalus (swollen brain), Arnold-Chiari malformation (mishapen posterior brain), absent corpus callosum
- Vision and hearing impairment
- Majority (> 80%) reported to have normal psychological functioning
Focal dermal hypoplasia (Goltz syndrome)
What treatment is available for focal dermal hypoplasia?
Treatment will depend on the specialty care required for each specific problem. Often there will be specialists from multiple disciplines involved.
For cutaneous issues: telangectatic areas and papillomas may respond to vascular lasers; papillomas may be surgically removed if problematic.