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MEN2B Case Study

Satisfactory Essays
Choice “A” is the best answer. This patient has signs and symptoms consistent with multiple endocrine neoplasia 2B. These signs include mucosal neuromas, as seen in the images above. He also has headaches, palpitations and sweating episodes consistent with a pheochromocytoma. The etiology of MEN2B stems from mutations in RET, a transmembrane proto-oncogene. Although its function is still unknown, the protein produced by RET is critical during embryonic development of the enteric nervous system and kidneys. RET is a RTK that consists of 3 domains, including a cysteine-rich extracellular receptor domain, a hydrophobic transmembrane domain, and an intracellular tyrosine kinase catalytic domain. Point mutations associated with MEN 2A and the FMTC-only subtype has been identified in exons 10 and 11. Evidence of genotype/phenotype correlation exists. Almost all individuals with MEN 2B have an identical mutation in codon 918 of exon 16. Inheritance is autosomal dominant, with variable penetrance and expressivity [1].

Choice “B” is not the best answer. An autosomal recessive disorder develops when two copies of an abnormal gene are passed onto the offspring. Examples of autosomal recessive disorders include cystic fibrosis, sickle cell anemia, and Tay-Sachs disease.
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X-linked dominant inheritance is a mode of genetic inheritance by which a dominant gene is carried on the X chromosome. X-linked dominant traits do not necessarily affect males more than females (unlike X-linked recessive traits). The exact pattern of inheritance varies, depending on whether the father or the mother has the trait of interest. All daughters of an affected father will also be affected but none of his sons will be affected (unless the mother is also affected). In addition, the mother of an affected son is also affected (but not necessarily the other way round). Examples of X-linked dominant conditions include Rett syndrome, Fragile X syndrome, and Alport
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