Ectrodactyly-Ectodermal Dyspl... Health Article

Signs and symptoms

In order to understand the signs and symptoms of EEC syndrome it is important to understand a little about early embryonic development. Very early in pregnancy, the cells that will develop into the embryo are organized as a small round ball. These cells eventually separate into three distinct layers: the endoderm, the mesoderm, and the ectoderm. The endoderm can be thought of as the inside layer. Cells from the endoderm will eventually form into the lining of the digestive tract and the respiratory tract. The mesoderm can be thought of as the middle layer, and the cells of the mesoderm will eventually become the muscles, bones, cartilage, heart, and blood vessels. The ectoderm (involved in EEC syndrome) can be thought of as the outside layer. The cells of the ectoderm will eventually become the skin, hair, nails, brain, and nervous system. Any disruption of the development of the ectoderm will lead to disruption of the organs formed from this layer.

EEC syndrome is the result of a disruption of the ectoderm layer very early in development. This disruption causes the specific defects seen in EEC syndrome, including defects of the skin, hair, nails, and other organs. As of 2005, the exact nature of this disruption or problem in formation of the ectooderm is not known. Research in this area is ongoing.

EEC syndrome is a disorder that causes multiple congenital abnormalities. Although these anomalies appear to be diverse, they all arise from the same underlying defect, or insult, to the early embryonic ectodermal tissue. Ectodermal tissue is responsible for the formation of the limbs, nails, eyes, skin, hair, teeth, kidneys, glands, and face. All of these organs and systems are affected to some degree in EEC syndrome. Most individuals will have some of the EEC abnormalities, but it is very rare for one individual to have all of these abnormalities.

Abnormalities of the hands and feet of individuals affected with EEC may include:

• ectrodactyly (lobster-claw deformity) of the hands and feet
• syndactyly (webbed fingers or toes)

Abnormalities of the eyes of affected individuals may include:

• nasolacrimal duct obstruction (tear duct obstruction)
• excessive lacrimation (tears)
• blephariphimosis/blepharospasm
• corneal ulcers and scarring
• telecanthus
• photophobia

Skin abnormalities of individuals affected with EEC may include:

• dry skin
• lack of sweat pores
• thin skin/generalized skin atrophy
• hyperkeratosis (thickened skin)

Individuals affected with EEC may have hair abnormalities, including:

• dry, brittle hair
• generalized depigmentation of hair
• fine hair
• sparse hair, or alopecia areata

Teeth abnormalities in affected individuals may include:

• abnormalities in the tooth buds, resulting in missing or abnormally shaped teeth
• defective enamel
• small teeth

Abnormalities of the kidneys of affected individuals may include:

• dilated ureters or uretral atresia
• double ureters
• hydronephrosis
• multiple renal cysts
• renal agenesis
• renal dysplasia

Gland abnormalities of individuals affected with EEC may include:

• absent or hypoplastic thymus
• hypopituitarism
• isolated growth hormone deficiency
• pituitary diabetes insipidus

Facial abnormalities of affected individuals may include:

• cleft lip
• cleft palate
• malformed ears

Additionally, individuals affected with EEC can experience nail dystrophy.

There are two other ectodermal dysplasia syndromes that closely resemble EEC syndrome: Rapp-Hodgkin syndrome (RHS) and ankyloblepharon-ectodermal defects-cleft lip and palate (AEC) syndrome (also known as Hay Wells syndrome). These syndromes share some of the specific findings of EEC syndrome, but differ in important ways.

The Rapp-Hodgkin syndrome (RHS) is another type of ED associated with cleft lip and palate. However, RHS does not share the hand and foot defects of EEC syndrome. People with RHS do have some sweating problems, and their hair grows slowly and is coarse. Some affected individuals have persistent scalp dermatitis. As a rule, individuals with RHS have more teeth than those with EEC. General health, intelligence, and lifespan are within normal expectations.

The Hay-Wells syndrome (HWS), also known as the anklyloblepharon-ectodermal dysplasia-cleft lip and palate syndrome, is one of several syndromes that affect both the ectoderm and structures that do not derive from the ectoderm. The scalp hair is sparse and wiry, while the eyelashes are sparse or absent. The nails may be absent or malformed, and the teeth and sweat glands may also be affected. The feature that differentiates HWS from the other ectodermal dysplasias is the fusion of the upper and lower eyelids usually by narrow bands of tissue connecting the lids (anklyloblepharon). Patients may also have inflammatory dermatitis of the scalp.