The exact function of phosphorylating DHCR7 is yet unknown, but it is thought to be involved in the regulation of its activity. Mutations and incidence
SLOS is an autosomal recessive disorder. More than 130 different types of mutations have been identified. Missense mutations (single nucleotide change resulting in a code for a different amino acid) are the most common, accounting for 87.6% of the SLOS spectrum. These typically reduce the function of the enzyme but may not inhibit it completely. Much depends on the nature of the mutation (i.e. which amino acid is replaced and where). Null mutations are much less common, these mutations produce either a completely dysfunctional enzyme, or no enzyme at all. Thus, missense mutations may be more common overall because they are less lethal than nonsense mutations; nonsense mutations may simply result in spontaneous abortion.The IVS8-1G>C is the most frequently reported mutation in DHCR7. This disrupts the joining of exons eight and nine, and results in the insertion of 134 nucleotides into the DHCR7 transcript. This is a nonsense mutation, thus patients that are homozygous for this allele are severely affected. It is thought that this mutation first occurred in the British Isles, and it has a carrier (those that are heterozygous for the allele but not affected) frequency of 1.09% for Caucasians of European heritage. The frequency of mutations differs for various ethnicities, depending on the origin of the mutation.
The appearances can vary but generally show wide, ribbon-like filaments that generally do not have septa and that—unlike in aspergillosis—branch at right angles, resembling antlers of a moose, which may be seen to be invading blood vessels. Other
Matrix-assisted laser desorption/ionization may be used to identify the species. A blood sample from an artery may be useful to assess for metabolic acidosis. Differential diagnosis
Other filamentous fungi may however look similar. It may be difficult to differentiate from aspergillosis. Other possible diagnoses include anthrax, cellulitis, bowel obstruction, ecthyma gangrenosum, lung cancer, clot in lungs, sinusitis, tuberculosis and fusariosis. Prevention
Preventive measures include wearing a face mask in dusty areas, washing hands, avoiding direct contact with water-damaged buildings, and protecting skin, feet, and hands where there is exposure to soil or manure, such as gardening or certain outdoor work. In high risk groups, such as organ transplant patients, antifungal drugs may be given as a preventative. Treatment
Treatment involves a combination of antifungal drugs, surgically removing infecting tissue and correcting underlying medical problems, such as diabetic ketoacidosis. Medication
Once mucormycosis is suspected, amphotericin B at an initial dose of 1 mg is initially given slowly over 10–15 minutes into a vein, then given as a once daily dose according to body weight for the next 14 days. It may need to be continued for longer. Isavuconazole and Posaconazole are alternatives. Surgery
Surgery can be very drastic, and, in some cases of disease involving the nasal cavity and the brain, removal of infected brain tissue may be required.