Less severe mutations result in a collodion membrane and congenital ichthyosiform erythroderma-like presentation.ABCA12 is an ATP-binding cassette transporter (ABC transporter), which are members of a large family of proteins that hydrolyze ATP to transport cargo across cell membranes. ABCA12 is thought to be a lipid transporter in keratinocytes necessary for lipid transport into lamellar granules during the formation of the lipid barrier in the skin. Diagnosis
The diagnosis of harlequin-type ichthyosis relies on both physical examination and laboratory tests. Physical assessment at birth is vital for the initial diagnosis of harlequin ichthyosis. Physical examination reveals characteristic symptoms of the condition especially the abnormalities in the skin surface of newborns. Abnormal findings in physical assessments usually result in employing other diagnostic tests to ascertain the diagnosis.Genetic testing is the most specific diagnostic test for harlequin ichthyosis. This test reveals a loss of function mutation on the ABCA12 gene. Biopsy of skin may be done to assess the histologic characteristics of the cells. Histological findings usually reveal hyperkeratotic skin cells, which leads to a thick, white and hard skin layer. Treatment
Constant care is required to moisturize and protect the skin. The hard outer layer eventually peels off, leaving the vulnerable inner layers of the dermis exposed. Early complications result from infection due to fissuring of the hyperkeratotic plates and respiratory distress due to physical restriction of chest wall expansion.Management includes supportive care and treatment of hyperkeratosis and skin barrier dysfunction. A humidified incubator is generally used. Intubation is often required until nares are present.
Palpating the chest as it expands and tapping the chest wall to identify dull, non-resonant areas can identify stiffness and fluid, signs of CAP. Listening to the lungs with a stethoscope (auscultation) can also reveal signs associated with CAP. A lack of normal breath sounds or the presence of crackles can indicate fluid consolidation. Increased vibration of the chest when speaking, known as tactile fremitus, and increased volume of whispered speech during auscultation can also indicate the presence of fluid.Several tests can identify the cause of CAP. Blood cultures can isolate bacteria or fungi in the bloodstream. Sputum Gram staining and culture can also reveal the causative microorganism. In severe cases, bronchoscopy can collect fluid for culture. Special tests, such as urinalysis, can be performed if an uncommon microorganism is suspected. Chest X-rays and X-ray computed tomography (CT) can reveal areas of opacity (seen as white), indicating consolidation. CAP does not always appear on x-rays, sometimes because the disease is in its initial stages or involves a part of the lung not clearly visible on x-ray. In some cases, chest CT can reveal pneumonia not seen on x-rays. However, congestive heart failure or other types of lung damage can mimic CAP on x-ray.When signs of pneumonia are discovered during evaluation, chest X-rays and examination of the blood and sputum for infectious microorganisms may be done to support a diagnosis of CAP. The diagnostic tools employed will depend on the severity of illness, local practices and concern about complications of the infection.