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Investigations on taste blindness with thiocarbamides II (1). Intra-pair discrepancy of taste in pairs of identical twins

Published online by Cambridge University Press:  01 August 2014

P. E. Verkade ,
B. M. Wepster  and
L. J. Stegerhoek
P. E. Verkade
Affiliation:
Laboratory of Organic Chemistry, Technical University, Delft, Netherlands
B. M. Wepster
Affiliation:
Laboratory of Organic Chemistry, Technical University, Delft, Netherlands
L. J. Stegerhoek
Affiliation:
Laboratory of Organic Chemistry, Technical University, Delft, Netherlands

Summary

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During the World Twin Congress held at Eindhoven (Netherlands) in 1957 we tested 70 pairs of identical twins for their ability to taste para-ethoxyphenylthiocarbamide (EPTC). In 2 pairs a clear intra-pair discrepancy of taste was encountered. The tests with these 2 pairs were continued weekly for about six months. The result was always the same. One member of the pair found a bitter taste even in a solution 1:320,000 of EPTC; the other member considered even a solution 1:5,000 of this compound, i.e. a solution of the «taste blindness threshold concentration», completely tasteless. The former is a «taster», the latter is a «non-taster».

A similar intra-pair discrepancy in taste with regard to phenylthiocarbamide (PTC) in pairs of identical twins has been found by Ardashnikov c.s. and by Rife.

The ability to taste certain thiocarbamides without doubt being a hereditary property, the discrepancy of taste found must have an exogenic cause, the nature of which is unknown.

The fact in question is discussed on the basis of the well-established bimodality of the taste threshold concentration/frequency curve for thiocarbamides. It is pointed out that the «non-tasters» of the pairs of identical twins under consideration must be regarded as «crypto tasters». Their taste threshold concentration lies on the «wrong» side of the (more or less arbitrarily adopted) «taste blindness threshold concentration» (1:5,000 for EPTC and PTC).

The consequences of the existence of «crypto tasters» and also «crypto non-tasters» for work in the field of genetics with the aid of appropriate thiocarbamides are briefly indicated.

Riassunto

RIASSUNTO

Durante il Congresso Mondiale dei gemelli tenutosi a Eindhoven (Olanda) nel 1957 abbiamo esaminato 70 coppie di gemelli identici rispetto alla loro capacità di gustare la para-etossifeniltiocarbamide (EPTC). In due coppie fu riscontrata una chiara discordanza gustativa intracoppia. Le prove con queste due coppie furono continuate settimanalmente per circa 6 mesi. Il risultato fu sempre lo stesso. Un membro della coppia trovava un sapore amaro anche in una soluzione di 1:320.000 di EPTC; il cogemello considerava insapore anche una soluzione di 1 : 5.000 dello stesso composto, cioè una soluzione di «concentrazione limite di sensibilità gustativa». Il primo era un «gustatore», il secondo un «non gustatore».

Una simile discordanza gustativa per la feniltiocarbamide (PTC) in coppie di gemelli identici è stata trovata da Ardashnikov e da Rife.

La capacità di gustare certe tiocarbamidi essendo indubbiamente una proprietà ereditaria, la discordanza gustativa deve avere una causa esogena, la cui natura è sconosciuta.

La questione viene discussa in base alla ben nota bimodalità della curva concentrazione di soglia gustativa / frequenza. Si fa notare che i «non gustatori» delle coppie di gemelli identici considerati devono considerarsi come «cripto-gustatori». La loro concentrazione di soglia gustativa si trova dal lato «sbagliato» di quella che più ο meno arbitrariamente è stata adottata come «concentrazione limite di sensibilità gustativa» (1:5.000 per la PTC e la EPTC).

Vengono brevemente indicate le conseguenze della esistenza di «cripto-gustatori» ed anche di «cripto-non-gustatori» per le ricerche genetistiche col sussidio di appropriate tiocarbamidi.

Résumé

RÉSUMÉ

Pendant le Deuxième Congrès Mondial des Jumeaux qui a eu lieu à Eindhoven (Pays Bas) en 1957, nous avons examiné 70 couples de jumeaux identiques par rapport à leur capacité de goûter la para-éthoxyphénilthiocarbamide (EPTC). Chez deux couples on a trouvé une différence intra-couple bien marquée. Les examens sur ces deux couples ont été continués chaque semaine pendant six mois. Les résultats en ont été toujours les mêmes. L'un des jumeaux dans chaque couple goûtait encore amer avec une solution 1:320.000 de EPTC; l'autre jumeau considérait tout à fait insipide une solution 1:5.000 du même composé, soit une solution de «concentration de seuil de sensibilité gustative». Le premier jumeau est un «goûteur», l'autre un «non-goûteur».

Une différence semblable intra-couple par rapport à la capacité de goûter la phênilthiocarbamide (PTC) a été observée chez des couples de jumeaux identiques par Ardashnikov et par Rife.

La capacité de goûter certaines thiocarbamides étant sans doute une qualité héréditaire, la différence trouvée en ces cas doit avoir une cause extérieure dont la nature est inconnue.

La question est discutée sur la base de la bimodalité reconnue de la courbe concentration de seuil gustatif / fréquence pour les thiocarbamides. On conclut que les «non-goûteurs» des couples de jumeaux identiques étudiées sont à considérer comme «crypto-goûteurs». Leur concentration de seuil gustatif se trouve du côté «érroné» de celle que l'on a (un peu arbitrairement) adoptée comme «concentration de seuil de sensibilité gustative» (1: 5.000 pour l'EPTC et la PTC).

On indique les conséquences de l'existence des «crypto-goûteurs» et des «crypto-goûteurs» et des «crypto-non-goûteurs» pour les recherches de génétique par le moyen de thiocarbamides appropriées.

Type
Research Article
Information
Acta geneticae medicae et gemellologiae: twin research , Volume 8 , Issue 3 , July 1959 , pp. 361 - 368
Copyright
Copyright © The International Society for Twin Studies 1959

References

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