Leukocyte adhesion deficiency (LAD) is a genetic defect that leads to recurrent

Question

Leukocyte adhesion deficiency (LAD) is a genetic defect that leads to recurrent infections in the tissue and severe problems with wound healing. LAD patients also develop severe gingivitis (infections and inflammation of the gums). In LAD, leukocyte migration into tissues is severely impaired. All of these problems can be traced back to a genetic defect. Of the genetic defects listed below, which is the most likely cause of LAD? A mutation that introduces a stop codon into a gene that encodes part of the LFA-1 molecule (leading to a truncated protein). O A defect in blood cell development that leads to very low numbers of monocytes, but normal numbers of other blood cells. A mutation in the promoter of the TNFa gene that leads to high TNFa expression in tissue. A mutation that increases the stability of the E-selectin ligand protein

Explanation / Answer

Answer is A

A mutation that introduces a stop codon into a gene that encodes part of the LFA-1 molecule( leading to truncated protein)

The main gene responsible for leukocyte adhesion deficiency is ITGB2 mutations. This produces ?2 integrins like CD11a/CD18 (LFA-1). The mutated gene may lead to the production of ?2 subunits and that are unable form other ?2 integrins and prevents the attachment to the blood vessels and does not cross walls of vessels to provide an immune response. This can results in frequent infection, delayed wound healing and gingivitis.

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