In other words, for an individual to inherit the leukodystrophy phenotype, he or she must carry two of the recessive, mutant alleles. Krabbe disease and metachromatic leukodystrophy (MLD) are two of such type. MLD is found on human chromosome 22 at position q13.31. Another type of inherited leukodystrophy is X-linked adrenoleukodystrophy (X-ALD). As its name implies, this type of leukodystrophy is the result of a mutation found on the X-chromosome. It is also carried in a recessive pattern. The X chromosome is a sex chromosome, and since women have two "chances" of acquiring a normal X chromosome (one maternal, one paternal), and males only one (one maternal), this disease is more likely to be seen in men than in women. The mutation resulting in adult-onset leukodystrophy is mapped at 5q23. Pathophysiology
Although there are nearly forty different types of leukodystrophies, many are lacking in formal and comprehensive research. Most of the research so far has been done on five types: (1) metachromatic leukodystrophy (MLD), (2) Krabbe disease, (3) X-Linked adrenoleukodystrophy (ALD), (4) Canavan disease, and (5) Alexander disease. Each type of leukodystrophy has a unique pathophysiology, but all five of these in some way affect a subset of glial cells, therefore disrupting myelin production and maintenance, and usually involve a mutation involving genes that code for enzymes necessary for the catabolism of very long chain fatty acids (VLCFAs) that are toxic to the myelin-producing cells of the central nervous system.
Risk factors
Whilst diet has long been known to be linked to laminitis, there is emerging evidence that breed and body condition also play a role. Levels of hormones, particularly adiponectin, and serum insulin are also implicated, opening up new possibilities for developing early prognostic tests and risk assessments. Diagnosis
Early diagnosis is essential to effective treatment. However, early outward signs may be fairly nonspecific. Careful physical examination typically is diagnostic, but radiographs are also very useful. Clinical signs
Increased temperature of the wall, sole and/or coronary band of the foot
A pounding pulse in the digital palmar artery
Anxiety and visible trembling
Increased vital signs and body temperature
Sweating
Flared nostrils
Walking very tenderly, as if walking on egg shells
Repeated "easing" of affected feet, i.e. constant shifting of weight
Lameness with a positive response to hoof testers at the toe
The horse stands in a "founder stance" in attempt to decrease the load on the affected feet. If it has laminitis in the front hooves, it will bring its hind legs underneath its body and put its fore legs out in front. In cases of sinking, the horse stands with all four feet close together, like a circus elephant.