Details Pertaining to Ptc Filter Paper Test

Principal Investigator: James Fozard
Collaborating Investigators: (none)
Year First Collected: 1958
Year Last Collected: 1985
Frequency of Collection: n/a
Subset Data Files on the VMS Cluster? Files info403.*, Inactive as of 11/97. Available to all users authorized to access Common BLSA Data Set.

Data Type Notes: Description: PTC stands for phenythiocarbamide. When tasted on a piece of appropriately treated filter paper, the expected taste experience should be reported as "bitter." Those who respond positively to the test material are believed to have inherited a dominant genetic trait for this sensory experience. Those who do not respond positively, have inherited a recessive gene.

In practice, a nontaster was identified in two ways: first, the person would not report a taste of bitter or some closely related experience; second, the person would not be able to distinguish the paper treated from a second, untreated control paper. If the person is negative with respect to both, (s)he was a nontaster. This explains why there were two questions asked -- one about the taste experience, and the other about whether the person could distinguish between the treated and untreated papers.

According to the description, the PTC test was part of a larger protocol called "The Genetic Survey." The other parts included a "family history," data on birth and death of relatives from grandparents, parents, siblings, offspring and similar information for spouse. Much of this information has been gathered in more than one format in the BLSA. Another element was the smoking history. Whether this was the same or different than the present one is not known. The final part was a blood typing test performed at a laboratory in the Baltimore City Hospital by a Dr. Thelma Bias. The records were to be stored with the family history.

Frequency: The documentation states that the test was to be administered to participants on each visit. It is not clear why repeated measures of a test for an inherited trait would have to be repeated.


JM - Disclaimer

Revised 12/09/98 -- Send comments to our Web Master .