Question

Explain why certain porphyria’s (e.g., acute intermittent porphyria) may show intermittent clinical expression.

Answer 1

Acute intermittant porphyria occurs in the liver prophyria. This intermittant clinical condition is caused by deficiency in the enzyme porphobilinogen deaminase (PBGD), also known as hydroxymethylbilane synthase (HMBS). Ths genetic condition if due to the mutation in the HMBS gene. In some patients, the presence of the HMBS genetic mutation does not allow to cause any symptoms. These individuals develop latent AIP disorder. This is because the mutation of the gene is not alone responsible for the disease. The PBGD deficiency is not alone enough to cause the disease but also involve some hormones, drugs or dietary changes that trigger the disorder. So those who show intermittent clinical symptoms appear latent expressors as the secretion of some hormones are required to trigger the symptoms of the disorder, although the gene is inherited.