Deficiency
A deficiency of porphobilinogen synthase is usually acquired (rather than hereditary) and can be caused by heavy metal poisoning, especially lead poisoning, as the enzyme is very susceptible to inhibition by heavy metals.Hereditary insufficiency of porphobilinogen synthase is called porphobilinogen synthase (or ALA dehydratase) deficiency poprhyria. It is an extremely rare cause of porphyria, with less than 10 cases ever reported. All disease associated protein variants favor hexamer formation relative to the wild type human enzyme. PBGS as the prototype morpheein
The morpheein model of allostery exemplified by PBGS adds an additional layer of understanding to potential mechanisms for regulation of protein function and complements the increased focus that the protein science community is placing on protein structure dynamics.This model illustrates how the dynamics of phenomena such as alternate protein conformations, alternate oligomeric states, and transient protein-protein interactions can be harnessed for allosteric regulation of catalytic activity. References
External links
Human ALAD genome location and ALAD gene details page  in the UCSC Genome Browser. delta-Aminolevulinic+Acid+Dehydratase at the US National Library of Medicine Medical Subject Headings (MeSH)
http://www.omim.org/entry/125270?search=pbgs&highlight=pbgs


== Further reading ==
Genital warts are a sexually transmitted infection caused by certain types of human papillomavirus (HPV). They are generally pink in color and project out from the surface of the skin. Usually they cause few symptoms, but can occasionally be painful. Typically they appear one to eight months following exposure. Warts are the most easily recognized symptom of genital HPV infection.HPV types 6 and 11 are responsible for causing majority of genital warts whereas HPV types 16, 18, 31, 33, and 35 are also occasionally found. It is spread through direct skin-to-skin contact, usually during oral, genital, or anal sex with an infected partner. Diagnosis is generally based on symptoms and can be confirmed by biopsy. The types of HPV that cause cancer are not the same as those that cause warts.Some HPV vaccines can prevent genital warts as may condoms. Treatment options include creams such as podophyllin, imiquimod, and trichloroacetic acid. Cryotherapy or surgery may also be an option. After treatment warts often resolve within six months. Without treatment, in up to a third of cases they resolve on their own.About 1% of people in the United States have genital warts. Many people, however, are infected and do not have symptoms. Without vaccination nearly all sexually active people will get some type of HPV at one point in their lives. The disease has been known at least since the time of Hippocrates in 300 BC.