Environmental risk factors are also needed to help create enough genetic mutations to cause disease. Evidence for the role of the environment is seen in childhood ALL among twins, where only 10–15% of both genetically identical twins get ALL. Since they have the same genes, different environmental exposures explain why one twin gets ALL and the other does not.Infant ALL is a rare variant that occurs in babies less than one-year-old. KMT2A (formerly MLL) gene rearrangements are most common and occur in the embryo or fetus before birth. These rearrangements result in increased expression of blood cell development genes by promoting gene transcription and through epigenetic changes. In contrast to childhood ALL, environmental factors are not thought to play a significant role. Aside from the KMT2A rearrangement, only one extra mutation is typically found. Environmental exposures are not needed to help create more mutations. Risk factors
Genetics
Common inherited risk factors include mutations in ARID5B, CDKN2A/2B, CEBPE, IKZF1, GATA3, PIP4K2A and, more rarely, TP53. These genes play important roles in cellular development, proliferation, and differentiation. Individually, most of these mutations are low risk for ALL. Significant risk of disease occurs when a person inherits several of these mutations together.The uneven distribution of genetic risk factors may help explain differences in disease rates among ethnic groups. For instance, the ARID5B mutation is less common in ethnic African populations.Several genetic syndrome also carry increased risk of ALL.
Moorens ulcer is a rare idiopathic ocular disorder that may lead to blindness due to progressive destruction of the peripheral cornea. Although the etiology of Moorens ulcer is poorly understood, recent evidence suggests that the pathogenesis of this disease appears to be the result of an autoimmune process directed against molecules expressed in the corneal stroma.Moorens ulcer is also defined as a special and the most common type of peripheral ulcerative keratitis (PUK). Signs and symptoms
Symptoms of Moorens ulcer can include:
Pain in the affected eye(s)
Redness of the affected eye(s)
Progressive ulceration of the cornea
Blurred vision
Photophobia
TearingSome epidemiological studies have noted that men tend to be affected more than women. Classification
The most commonly used classification was proposed by Watson in 1997. He divided the disease into three types based on the clinical picture:
Unilateral Moorens ulceration is characterized by extremely painful progressive ulceration of the cornea in one eye. This form is more common in elderly patients. Bilateral aggressive Moorens ulceration which is observed more often in young patients and progresses along the entire circumference, then captures the central area of the cornea. Bilateral indolent Moorens ulceration (BIM) usually occurs in middle-aged patients and manifested by a progressive peripheral corneal guttering in both eyes. Risk factors
Several risk factors affecting the development of Moorens ulcer have been suggested. Corneal trauma
Previous ocular trauma or infection can cause disruption of the corneal integrity resulting in the expression of tissue-specific antigens that are normally hidden from the immune system.