What are the other Names for this Condition? (Also known as/Synonyms)
- RXLI (Recessive X-Linked Ichthyosis)
- Steroid Sulfatase Deficiency Disease (SSDD)
- X-Linked Ichthyosis (XLI)
What is X-linked Recessive Ichthyosis? (Definition/Background Information)
- X-Linked Recessive Ichthyosis (Recessive X-Linked Ichthyosis or RXLI) is a skin disorder that manifests as dry scales, resulting in a rough-dry skin texture. It is a congenital disorder and caused by specific genetic defects in the STS gene
- Ichthyosis, in general, is of many different types. Some types are congenital and others are acquired. Ichthyosis can also be present as an acquired symptom in other disorders
- There are 5 different types of inherited Ichthyosis disorders that include the following:
- Ichthyosis Vulgaris; it is the most common form of Ichthyosis
- Lamellar Ichthyosis, Type 1 to Type 5
- Epidermolytic Hyperkeratosis (or Bullous Ichthyosis)
- Congenital Ichthyosiform Erythroderma
- X-Linked Recessive Ichthyosis
- The diagnosis for X-Linked Recessive Ichthyosis usually involves a complete medical history assessment, physical examination, and genetic testing
- Once the condition is diagnosed, a symptomatic treatment of X-Linked Recessive Ichthyosis is undertaken, since the condition cannot be cured. This can help prevent complications such as skin infections (that may occur frequently otherwise)
- The prognosis of X-Linked Recessive Ichthyosis depends on the severity of the signs and symptoms. Individuals with mild signs and symptoms have a better prognosis than those with severe conditions
Who gets X-linked Recessive Ichthyosis? (Age and Sex Distribution)
- X-Linked Recessive Ichthyosis occurs almost always in males with a general incidence of 1 in 2,000-6,000. However, rarely, females are also affected
- The symptoms may occur at birth or may be observed in the neonatal period
- The condition is seen all over the world; there is no particular geographical restriction or ethnic/racial preference
- Nevertheless, RXLI has a higher incidence among the Danish populations. It is also more common in Mexico than USA
- After Ichthyosis Vulgaris, X-Linked Recessive Ichthyosis is the most common type of Ichthyosis
What are the Risk Factors for X-linked Recessive Ichthyosis? (Predisposing Factors)
- In case of X-Linked Recessive Ichthyosis, a positive family history of Ichthyosis is an important risk factor
It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases ones chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.
Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.
What are the Causes of X-linked Recessive Ichthyosis? (Etiology)
- X-Linked Recessive Ichthyosis is caused by an abnormality in the development of the part of the skin called epidermis. The abnormality occurs during development of the epidermis layer of the skin
- The condition is inherited in an X-linked fashion (X-linked recessive disorder). Typically, the mother is the “carrier” of the defective gene and does not develop the condition. Since the defective, recessive gene is carried on the X-chromosome (males have only one X-chromosome), it is expressed in males. Females are usually carriers of the defect
- The gene abnormality is either a mutation or deletion that takes place in the STS gene. STS gene is responsible for making steroid sulfate enzyme. This gene is located on chromosome X at band XP 22.3. Hence, the disorder is also known as Steroid Sulfatase Deficiency Disease (SSDD)
- X-Linked Recessive Ichthyosis is not a contagious condition. RXLI is caused by a genetic defect, and it cannot be passed on from one individual to another through direct contact
X-linked recessive: X-linked recessive conditions are traits or disorders that occur when two copies of an abnormal gene are inherited on a sex chromosome (X or Y chromosome). All X-linked recessive traits are fully evident in males, because they have only one copy of the X chromosome. This means that there is no normal gene present to mask the effects of the mutant copy. All males who are affected will pass the mutated gene onto their female offspring, because they must inherit one copy of the X chromosome from each parent. This means that they will be unaffected carriers. Females are rarely affected by X-linked recessive disorders because they have two copies of the X chromosome. In the rare case that they inherit two mutated copies of the gene, they will inherit the condition.
What are the Signs and Symptoms of X-linked Recessive Ichthyosis?
The signs and symptoms of X-Linked Recessive Ichthyosis vary from individual to individual. Some have mild signs and symptoms, while others have severe signs and symptoms. The signs and symptoms of RXLI may include:
- The condition causes dry scaly skin; symptoms start to occur anytime from birth to 12 months
- The pattern of affected areas includes the legs, neck, chest, and abdomen. The palms and soles are spared from scaling
- The dry scales tend to decrease during summer
In addition to skin scaling, one may find additional signs and symptoms.
- The cornea of the eye may show opacity, which is due to pre-Descemet’s membrane opacity. However, it has been observed that vision is not generally affected
- X-Linked Recessive Ichthyosis may be associated with other diseases, undescended testis (cryptorchidisum), short stature, and mental retardation
- Most of the deliveries of males with X-Linked Recessive Ichthyosis had failure to initiate or progress. Cesarian section delivery is often necessary
- The signs and symptoms due to a particular genetic defect may vary significantly. This is called variable expression of a genetic defect
How is X-linked Recessive Ichthyosis Diagnosed?
It is important to determine the type of Ichthyosis. Many different modalities of testing are used to determine the type of Ichthyosis. However, an accurate diagnosis may not be always possible.
Some of the diagnostic steps for X-Linked Recessive Ichthyosis include:
- A through family history and a complete physical examination
- Complete blood count (CBC)
- Examination of peripheral blood smear under a microscope by a pathologist
- Ultrasonography may also show excess of amniotic fluid (polyhydramnios), in case of RXLI
- Genetic testing for specific type of mutations, such as STS gene deficiency, which is mapped to XP 22.3. This could be performed using FISH analysis of cultured amniotic fluid cells
- Maternal serum unconjugated estriol is useful in screening for placental STS deficiency and X-Linked Recessive Ichthyosis. Pregnant mothers with fetus having both the conditions may reveal a low maternal serum unconjugated estriol
- Amniotic fluid analysis may show decreased/absent STS cholesterol sulfate
- Skin biopsy (of the affected skin area) is performed and sent to a laboratory for a pathological examination, who examines the biopsy under a microscope. After putting together clinical findings, special studies on tissues (if needed) and with microscope findings, the pathologist arrives at a definitive diagnosis
- Fetal skin biopsy at 19 week gestation will help in diagnosing specific types of RXLI syndromes
- Bone marrow biopsy in individuals where underlying leukemia is the suspected cause of RXLI
Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.
What are the possible Complications of X-linked Recessive Ichthyosis?
X-Linked Recessive Ichthyosis can lead to many complications and these may include:
- Dehydration requiring frequent fluid intake
- Infections of the skin requiring frequent medical attention
- Heat intolerance: Skin is a very important organ to maintain the body temperature. Individuals with Ichthyosis have low heat tolerance of the body, resulting in overheating. This may result in heat strokes, which can be a dangerous condition
- In X-Linked Recessive Ichthyosis, increased risk of testicular cancer has been reported
- Individuals with Ichthyosis may have significant psychological issues. Due to abnormal skin, these individuals may face social ostracism. This can result in children and adults having low self-esteem and depression
How is X-linked Recessive Ichthyosis Treated?
Recessive X-Linked Ichthyosis (RXLI) is treated symptomatically. Special attention is paid to each individual’s specific condition and needs. There is no cure for the disorder and often a lifelong treatment course is essential.
- Dermatologist’s consultation is very critical in the treatment of RXLI. An ophthalmologist’s consultation is very important for eye-related abnormalities
- Medications, such as topical retinoids, to decrease scaling of the skin
- Humectants, such as propylene glycol, to hold moisture in the skin
- Keratolytics, such as lactic acid, to induce sloughing of the abnormal skin
- Oral retinoids are only rarely used
- Antibiotic treatment may be prescribed for secondary skin infections
- Proper eye care for dry eyes through eye drops, which help in keeping the dry eye surfaces moisturized
- Moisturizing creams may be used for dry surface of skin in the affected areas. Reducing exposure can help in decreasing the dryness
- Reducing exposure can help in decreasing skin dryness
How can X-linked Recessive Ichthyosis be Prevented?
Currently, there are no specific methods or guidelines to prevent X-Linked Recessive Ichthyosis, since it is a genetic condition.
- Genetic testing of the expecting parents (and related family members) and prenatal diagnosis (molecular testing of the fetus during pregnancy) may help in understanding the risks better during pregnancy
- If there is a family history of the condition, then genetic counseling will help assess risks, before planning for a child
- Active research is currently being performed to explore the possibilities for treatment and prevention of inherited and acquired genetic disorders such as X-Linked Recessive Ichthyosis
What is the Prognosis of X-linked Recessive Ichthyosis? (Outcomes/Resolutions)
The prognosis of X-Linked Recessive Ichthyosis is mostly excellent, although the condition persists throughout one’s life.
Additional and Relevant Useful Information for X-linked Recessive Ichthyosis:
Numerous conditions can have skin symptoms resulting in dry scaly skin. They include:
- Acrodermatitis enteropathica
- Thyroid disorder causing eye symptoms
- Atopic dermatitis
- Viral infections, such as caused by herpes zoster virus, and HIV
- Kaposi sarcoma in patients with AIDS
- Retinitis pigmentosa
- Acute leukemia