This is a rare hereditary condition characterized by the scaling of the skin, hair that are short, brittle and lusterless and at an increased risk of developing infections. Another feature of this condition is the predisposition of the affected individual to develop allergies, asthma and skin problems. This disorder is estimated to affect around 1 in 200,000 newborns.
Causes
This condition develops because of a genetic mutation in the SPINK5 gene which produces proteins called LEKT1. This protein is a type of serine peptidase inhibitor that controls the activity of enzymes known as serine peptidases in the outer layer of the skin that provides a protective barrier between the body and the environment. The LEKT1 protein is also involved in the normal hair growth, the development of white blood cells called lymphocytes that control the function of the immune system. The genetic mutation results in the inability of the LEKT1 to control the serine peptidase activity and its abnormal activity causes it to break down too many proteins in the outer tough layer of the skin called stratum corneum. This causes the excess shedding of the skin, abnormal hair growth and immune dysfunction that results in allergies, asthma and eczema. This condition is inherited in an autosomal recessive pattern meaning both the copies of the gene in each cell are defective.
Symptoms
Infants born with this disorder have reddened skin that is scaly all over and may be born prematurely. The hair shafts can break easily and are fragile or present ‘bamboo hair’ resulting in sparse hair. Some of the infants may be born with a sheath covering the skin called the collodion membrane which is usually shed in the first few weeks of their life. As they are missing the protection of the normal skin, they are at an increased risk of developing infections of the skin or throughout the body (sepsis) that can be life-threatening. As they are at the risk of becoming dehydrated, they may also develop hypernatremia which is the elevated sodium level in the blood that occurs from the excessive loss of fluid from the skin surface. The infants often have difficulty gaining weight which can be severe. They are also susceptible to developing asthma, allergies and eczema. As the dead skin cells are shed at an abnormal rate, it can accumulate in the ear canal affecting their hearing.
Diagnosis
The diagnosis is possible with the identification of characteristic findings when the infant is born. Molecular genetic testing can also help detect the mutation responsible for the development of the condition. The identification of the specific mutation can help determine the severity of the disorder.
Treatment
There is no cure for the disorder and the treatment is focused on providing symptomatic relief which is based on the individual’s specific needs. The treatment can include the regular use of emollients, moisturizing creams and lotions that should be perfume-free without additives to prevent allergic reactions. It is important to keep the skin moist and hydrated as much as possible. The oral antihistamines can help control the itchiness of the skin. The affected cases should also regularly get their ears checked to prevent the onset of a potentially hearing problem. As these children can suffer from poor temperature control, it is also important to prevent overheating.
References
https://ghr.nlm.nih.gov/condition/netherton-syndrome#inheritance
http://www.dermnetnz.org/topics/netherton-syndrome/
https://rarediseases.org/rare-diseases/ichthyosis-netherton-syndrome/
http://www.firstskinfoundation.org/types-of-ichthyosis/netherton-syndrome
