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   Table of Contents      
ARTICLES
Year : 1977  |  Volume : 25  |  Issue : 4  |  Page : 30-32

Phenyl thiourea (PTC) taste sensivitity in ocular disorders


1 Department of Ophthalmology, Govt. Medical College, Jammu, India
2 M.U. Institute of Ophthalmology, J.L.N. Medical College, Aligarh, India

Correspondence Address:
S S Soodan
Department of Ophthalmology, Govt. Medical College, Jammu
India
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Source of Support: None, Conflict of Interest: None


PMID: 659005

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How to cite this article:
Soodan S S, Gupta S, Rahi A H, Saiduzzaffar H. Phenyl thiourea (PTC) taste sensivitity in ocular disorders. Indian J Ophthalmol 1977;25:30-2

How to cite this URL:
Soodan S S, Gupta S, Rahi A H, Saiduzzaffar H. Phenyl thiourea (PTC) taste sensivitity in ocular disorders. Indian J Ophthalmol [serial online] 1977 [cited 2020 Nov 24];25:30-2. Available from: https://www.ijo.in/text.asp?1977/25/4/30/34610

Table 1

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Table 1

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The observations by Fox [4] and Black-slee [3] on the genetics of sensory thresholds and taste sensitivity to phenyl-thiourea (phenyl-thiocarba­mide or PTC) were the starting point for a significant study of Terry and Segall [15] who first demonstrated a sort of taste blindness in Dia­betes. This interesting study was further ex­tended to cases of thyroid diseases.

It was only in 1964 that Becker and Morton [1] tried to exploit the use of phenyl thiourea as a genetic marker in glaucoma. They are of the opinion that majority of open angle glaucoma cases (53%) fall in the category of non-tasters. This has further been corroborated by Kupfer, 1965 (53%). Becker and Ballin g observed that 60% offspring of open angle glaucoma patients were nontasters. In other surveys by the same authors, high applanation pressure values (over 25 mm Hg) were found twice as common among nontasters than in taster population.

In continuation to our earlier study (Soodan and Rahi [13] ) an attempt has been further made to evaluate the association of PTC taste sensitivity in normal Indians with open angle glaucoma population and mature senile cataract patients.


  Materials & Methods Top


Solutions of phenyl-thiourea (PTC) were prepared in the manner described by Harris and Kalmus [7] and Becker and Morton [1] . 1880 normal Indian subjects­male and female, of various age groups with no family history of glaucoma were studied for their ability to taste P.T.C. in dilutions of l0mg/100ml. The findings in turn were compared with 220 cases of open angle glaucoma and in 68 siblings and offspring of established cases of open angle glaucoma. The study was further extended to 260 cases of mature senile cataract to evaluate the incidence of taste insensitivity in this group.

A drop of P.T.C. solution was put with a dropper on the posterior surface of dried tongue so that no dilution with saliva occurred. The criteria of taste sensi­tivity was the appreciation of bitter taste. No leading questions were put to elucidate the taste sensitivity.


  Observations Top


These are shown in [Table - 1].


  Discussion Top


Since the ability to taste P.T.C. has got a genetic basis, the percentage of non-tasters shows a bimodial distribution in different races. According to Becker and Morton [1] 30% of normal caucasian population are non-tasters, whereas only 17% negro population is so. Kupfer [10] believes that 28% persons of white race are non-tasters. In the present study 38.83% persons of normal Indian population were grouped as non-tasters.

In the glaucomatous series 52.73% cases of established open angle glaucoma were non­tasters. Similarly 51.41% cases of suspected open angle glaucoma and 54.41% siblings and offspring of established open angle glaucoma patients had taste blindness for phenyl-thiourea. The relative high percentage of non-tasters in this population has been reported by Becker and Morton [1] ; Kupfer [10] and Becker and Balling and others [4],[5],[9],[12] .

Vogt quoted by sorsby [14] stressed the importance of genetic influences responsi­ble for mature senile cataract. The racial preponderance of cataract in Indians as compared to Mongolians, Africans, Europ­eans and Americans is well documented. It is more common in Indian community in South Africa than in Bantus of the same region. P.T.C. taste sensitivity was tested in 260 cases of mature senile cataract to find out possible influence of some genetic ground-work in formation of cataract and its relationship with racial distribution of the disease_ 41.15% patients were non-tasters for phenylthiourea. May be more than one factor is responsible for the genesis of cataract in different ethnic groups.

The open angle glaucoma is believed to have a hereditary basis. Its association with P.T.C. taste insensitivity suggests that this reagent can be used as a convenient genetic marker in various other ocular disorders whose hereditary character is in dispute or yet un­settled. At present no suitable explanation can be given for these findings but they are helpful in our abilities to diagnose the early stages of glaucoma process. May be further enzymatic and chromosomal studies could unravel this mystery.


  Summary Top


The association of phenyl-thiourea taste sensitivity has been studied in normal popula­tion, in established and suspected cases of open angle glaucoma; in siblings and offspring of established open angle glaucoma patients and in patients with mature senile cataract.

The percentage of nontasters is high in glaucomatous series as compared to normal Indian population. There is no significant increase of taste blindness in cataract patients than the normals.

 
  References Top

1.
Becker, B. and Morton, W.R., 1964, A.M.A. Arch. Ophthal., 72, 323.  Back to cited text no. 1
    
2.
Becker B. and Bailin, N., 1965, A.M.A. Arch. Ophthal., 74, 621.  Back to cited text no. 2
    
3.
Blakeslee, A.F., 1932, Proc. Nat. Acad. Sci., 18,120.  Back to cited text no. 3
    
4.
Duke Elder, S., 1969, System of Ophthalmology, 11, Henry Kimp, on London, p. 123.  Back to cited text no. 4
    
5.
Fraser, C.R., 1961, Lancit 1, 964.  Back to cited text no. 5
    
6.
Fox, A.L., 1932, Proc. U.S Nat. Acad. Sci., 18,155.  Back to cited text no. 6
    
7.
Harris, H. and Kalmus, H. 1949, Ann. Angen., 15, 24,  Back to cited text no. 7
    
8.
Harris, H., Kalmus, H. and Trotter, W.R., 1949, Lancet, 2, 1038.  Back to cited text no. 8
    
9.
Kitchin, F.D., et al, 1959, Brit. Med. J., 1, 1069.   Back to cited text no. 9
    
10.
Kupfer, C., 1965, J.A.M.A., 191, 592.  Back to cited text no. 10
    
11.
Mann, I., 1966, culture, race, climate and eye diseases. Charles c Thomas, illinois, P. 533.  Back to cited text no. 11
    
12.
Shepard, T.H. and Gartlar, S.M., 1960, Science 131, 929.  Back to cited text no. 12
    
13.
Soodan, S.S. and Rahi, A.H., 1968, paper presented at the XXVIII All India Ophthal. Conference held at Ahmedabad in January 1968.  Back to cited text no. 13
    
14.
Sorsby, A., 1970 Ophthalmic genetics. Butterworths, London. P. III.  Back to cited text no. 14
    
15.
Terry, M.C. and Segall G., 1947, J. Hered. 38,135.  Back to cited text no. 15
    



 
 
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