Jewish Population Groups in Israel CHAIAM SHEBA, ISRAEL ASHKENAZI and ARYEH SZEINBERG

Taste Sensitivity to Phenylthiourea among the Jewish Population Groups in Israel CHAIAM SHEBA, ISRAEL ASHKENAZI AND ARYEH SZEINBERG

Government Hospital, Tel Hashomer, Israel THE JEWISH NATION which settled on the Eastern Mediterranean shores about 12 centuries B.C. has been dispersed to different parts of the world for more than 2,000 years. Guarded by strict observance of religious laws, the Jews succeeded in preserving their national identity among the indigenous populations, through intermarriage and other forms of mixing with local populations, particularly during times of national and social upheavals, are known. From the point of view of the genetics of human populations it is, therefore, of great interest to investigate the similarities and differences among the various Jewish communities as well as in relation to local population groups. The State of Israel, where during a comparatively short period a gathering of the dispersed Jewish tribes from the whole world took place, presents a unique opportunity for the study of such a problem. Several genetic traits, namely blood group distribution, fingerprint patterns, the occurrence of an inherited glucose-6-phosphate dehydrogenase deficiency in erythrocytes and the distribution of Familial Mediterranean Fever, have been extensively investigated in the various Jewish communities in Israel (Mourant et al., 1958; Sachs and Bat-Miriam, 1957: Szeinberg et al., 1958; Heller et al., 1960). Little information exists about the distribution among the Jews, of another genetically determined trait, namely that of taste sensitivity to phenylthiourea. The results of our investigations of this trait are summarized in the present communication. METHODS The examinations were performed by the sorting technique of Harris and Kalmus (1949). Solution No. 1 contained 0.13 Gm. phenylthiourea per 100 ml. of tap water, the subsequent solutions (up to 13) were prepared by serial two-fold dilutions. The majority of the subjects were 8-22 years old. Relatives closer than first cousins have not been included in the material. All the subjects investigated were either immigrants or belonged to the first generation born in Israel.

RESULTS A well defined bimodal distribution of the taste sensitivity was observed in all the communities investigated (table 1). The modes among the tasters were characterized by sharp peaks in solution No. 9 or 10 with the exception of Received June 22, 1961. This investigation has been aided by (Grant No. RF: 60101 from the Rockefeller Foundation. 44 SHEBA ET AL. 45

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c c.E X ZA co -O X1c C) 0 0 C.b 46 TASTE SENSITIVITY IN ISRAEL the Gerba community (however, in that community the investigated sample was too small to permit definite conclusions). Among the non-tasters the modes were not so well defined, possibly owing to the relatively small num- bers of subjects in each group. The antimode was in all cases at the solution No. 5 (in the subsequent analysis the few subjects with taste threshold at this solution were included among the non-tasters).

TABLE 2. MEAN THRESHOLDS AND MODES OF TASTERS Total Males Females Taste . Taste Taste threshold threshold 'threshold Count No. Of Mean ± No. of Mean ± No. of Mean ± ofgin subjects St. Dev. Mode subjects St. Dev. Mode subjects St. Dev. Mode North. Africa 289 9.57±1.59 9 155 9.14±1.58 9 134 9.36±1.56 9 Kurdistan 111 9.57±1.47 9 56 9.33±1.59 9 55 9.63±1.32 9 Iraq & Persia 282 9.60±1.33 9 145 9.46X1.32 9 137 9.76±|1.33 9 Yemen 214 9.59±1.39 10 108 9.71±1.47 10 106 9.47±1.30 10 Europe Ashkenazim 349 9.50±e1.59 9 179 9.18±1.56 9 170 9.83±1.54 9 Balkan Non Ashke- nazim 79 9.60±1.32 10 30 9.40±! 0.99 9 49 9.73±1.50 10

The mean threshold among tasters from Gerba was 8.4. In the other communities it varied between 9.1 and 9.8 according to the sex and origin of the subjects (table 2). With one exception (Yemen), the mean threshold of tasters was 'always higher in females than in males, but statistically signfficant differences between sexes were found only within the Ashkenazi and the North African groups (table 3). Statistically significant differences between communities regarding the mean threshold among the tasters were found (table 3) between (1) males from Yemen and those of North African or Ashkenazic origin, and (2) males from North Africa and those from Iraq and Iran.

TABLE 3. MEAN THRESHOLDS AMONG TASTERS: STATISTICAL ANALYSIS OF THE RESULTS

N._of subiects Community Sex investigated t P Ashkenazim Males vs. Females 347 3.814 P<0.001 N. Africa " " " 287 2.610 P<0.01 N. Africa vs. Yemen " " Males 261 2.915 P<0.01 N. Africa vs. Iraq Pt " 298 2.885 P<0.01 Ashkenazim vs. Yemen " " " 283 2.807 P<0.01 The relative frequencies of non-tasters in the various communities are presented in table 4. Intersex differences were statistically significant only in the SHEBA ET AL. 47 North African community, in which a higher frequency of non-tasters among females than among males was observed (table 5). The highest frequency of non-tasters was observed in the Gerba and Cochin communities (41 and 31 per cent, respectively). The statistical analysis demonstrated that these two communities differed significantly from most of the other groups (table 5). It should be stressed, however, that only small sam-

TABLE 4: FREQUENCY OF NON-TASTERS

Total Males Females Countyof No. of % of non. No. of % of non- No. of % of non- origin subjects tasters subjects tasters subjects tasters Kurdistan 129 13.95±1-3.05 64 12.50± 4.13 65 15.38± 4.48 North- 340 15.00±1.94 174 10.91± 2.38 166 19.37+ 3.07 Africa' Iraq & 336 16.07±2.00 167 13.17± 2.62 169 18.93± 3.01 Persia Yemen 261 18.00±2.38 132 18.18± 3.36 129 17.82± 3.37 Europe- 440 20.68±1.93 227 21.14± 2.71 213 20.18± 2.75 Ashkenazim2 Balkan-Non- 101 21.78±4.11 41 26.82± 6.92 60 18.33± 4.99 Ashkenai Cochin 41 31.70±7.27 20 30.00±10.25 21 33.33+10.29 Gerba 41 41.46+7.69 14 50.00±13.36 27 37.03± 9.29

lThe results pertaining to the North African Jews comprise the findings among subjects from Tunisia (97), Morocco (184) and Tripolitania (59). As no significant differences were found between these groups they are presenetd as one community. 'A separate analysis was also performed for two groups of Ashkenazi subjects: (a) those originating from Poland, Western Russia, and Lithuania (number of subjects 319, frequency of non-tasters 20.8 per cent; (b) subjects from Roumania, Hungary and Czecho- slovakia (number of subjects 121, frequency of non-tasters 20.5 per cent). There is ex- cellent agreement between their frequencies and consequently all Ashkenazi Jews are presented as one group. ples from Gerba and Cochin communities have been examined, owing to the high rate of consanguinity and the necessity of exclusion of close relatives from the investigated material. The comparison between other groups is complicated by different findings among males and females. A close similarity in the frequency of non-tasters was observed among the Ashkenazi females and those from North Africa, Kurdistan, Iraq, Persia, Yemen and the Balkan countries (15.4 - 20.1 per cent non-tasters). On the other hand, some statistically significant differences were seen between males from these communities. A low frequency of non- tasters was found among the males from North Africa, Kurdistan, Iraq, and Persia (10.9 - 13.1 per cent), while a much higher frequency was seen among the Ashkenazi and non-Ashkenazi (Balkan) males from Europe (21.1 - 26.8 per cent respectively, tables 4 and 5). 48 TASTE SENSITIVITY IN ISRAEL

TABLE 5. FREQUENCY OF NON-TASTERS: STATISTICAL ANALYSIS OF THE RESULTS

Community Sex Chi square P. North Africa Males vs. females 4.64 0.02

DISCUSSION The distribution of taste sensitivity to phenylthiourea among Jews has been previously investigated only to a limited extent. Parr (1934) reported the following frequencies of non-tasters on the basis of tests performed with paper strips impregnated with phenylthiourea: Sep- hardic Jews 28 per cent, Ashkenazi Jews 31.5 per cent, Yemenites 32.3 per cent. The findings of Parr among non-Jews were: Egyptians 24.6 per cent, white Americans 30 per cent, Armenians 32 per cent, Arabs from Syria 36.5 per cent. The sorting technique of Harris and Kalmus is considered by most investigators a much more precise tool of measurement. By the use of this method Saldanha and Becak (1959) reported a frequency of 21.5 per cent non- tasters among Polish Jews living in Brazil as compared to 32.3 per cent among other Ashkenazi Jews from Central Europe living in that country. In the present investigation we have found about 20 per cent of non-tasters among all Ashkenazi Jews examined and no difference emerged between those from Western Russia, Poland and Lithuania on one hand, and Roumania, Hungary, and Czechoslovakia on the other. As no details about the composition of the group named "other Ashkenazi Jews" were given by the authors from Brazil, no comparison of our respective results is possible. Investigations of the distributions of taste sensitivity in various nations by the sorting technique leads to a crude division into three groups: (a) low frequency of non-tasters (e.g., Japanese, Chinese, African Negroes, 2-10 per SHEBA ET AL. 49 cent); (b) an intermediate group (for instance the Malayans, 18 per cent); (c) high frequency of non-tasters (West and North European nations and Hindus 24-33 per cent) (less Saldanha, 1958; Thambipillai, 1956). Our results suggest that Jews should be classified (with some exceptions) in the intermediate group. The anthropological and historical significance of these findings is at present not clear, owing to the lack of comparable data obtained by the same technique among the East European, Mediterranean, Middle-eastern and Near-eastern nations. A high frequency of non-tasters was found in two Jewish communities studied by us, namely, in the subjects from Cochin and Gerba. Both communities constituted small isolates in their countries of origin, leading to a high rate of marriage within families. The frequency of non-tasters in the Jewish Cochin community (about 31 per cent) is similar to that of Hindus (about 33 per cent) (Saldanha, 1959; Das, 1956). Also the ABO blood group distribution in the Cochin Jews dif- fers from all the other Jewish groups. A higher frequency of B than A gene was observed in this community, a feature which is found in many parts of India (Mourant et al., 1958; Gurevitch et al., 1954). In regard to the frequency of glucose-6-phosphate dehydrogenase deficiency, the Cochin Jews are intermediate between the Jews of the Near East and those of Yemen (Szeinberg et al., 1959). This abnormality has also been detected among Hindus, but its frequency in various Hindu groups is yet unknown (Szeinberg et al., 1959; Motulsky, 1960). The highest frequency of non-tasters was detected among the Gerba Jews. This finding suggests that they differ from all the other North African communities in which a significantly lower frequency of non-tasters was observed. A homogenous ABO blood group distribution has been found among Jews from Algeria, Tripolitania, Morocco and Tunisia, while a small sample of the Gerba Jews demonstrated a higher 0 and lower A blood group frequency (Mourant et al., 1958). No case of erythrocyte glucose-6-phosphate dehydrogenase deficiency has been detected among 100 Gerba Jews. The frequency of this abnormality in other North African communities was about I per cent (Szein- berg etal., 1959). The comparative evaluation of other results presented in this communication is complicated by the different findings in males and females. The frequency of non-tasters among females from Europe, North Africa, Near East and Yemen was almost identical, while among the males significant differences were observed. The reason for the divergent findings among males and females is not clear. Most investigators have found that females are more sensitive to phenylthiourea than males, (Kalmus, 1957-1958; Harris and Kalmus, 1956; Das, 1956; Falconer, 1947). In the present investigation, the mean threshold of tasters was usually higher in females than in males, but the differences were significant in two communities only. In the North African community the frequency of non-tasters was higher among females than among males, in all the other groups no significant sex differences are observed. Kalmus has recently proposed an improvement in the classification of the tasters by additional determination of sensitivity to quinine (Kalmus, 1957- so TASTE SENSITIVITY IN ISRAEL 58). Owing to technical difficulties this method has not been employed in the present investigation. However, in most of our investigated groups the antimode was quite distinct and it is felt that the additional test would not alter the results significantly. A deterioration of taste sensitivity with age has been demonstrated by Harris and Kalmus (1949), amounting to about one dilution step for each 20 years of age (Kalmus, 1957-58). In the present investigation the majority of subjects belonged to the 6-26 age group. When the frequencies of non-tasters in this age group alone are compared in the different communities, the results are essentially similar to those obtained for the whole samples. Age differences, therefore, cannot explain the intercommunity differences in the taste sensitivity observed among males.

SUMMARY Taste thresholds for phenylthiourea were measured in several Jewish communities living in Israel. The highest frequencies of non-tasters were found among Jews from Cochin (31 per cent) and from the Island of Gerba on the Tunisian coast of the Mediterranean (41 per cent). A close similarity of taste distribution was observed among females from Eastern Europe (Ashkenazic), the Balkan countries (non-Ashkenazic), Kurd- istan, Iraq, Persia, Algeria, Tunisia, Morocco, Tripolitania and Yemen (15 - 20 per cent of non-tasters). Significant differences were found between European males (21 - 27 per cent of non-tasters) and those from North Africa, Iraq and Persia (11 - 13 per cent of non-tasters). REFERENCES DAS, S.R. 1956. A contribution to the heredity of the P.T.C. taste character based on a study of 845 sib-pairs. Ann. Hum. Genet. 20: 334-343. FALCONER, D. S. 1947. Sensory threshold for solution of phenyl-thiocarbamide. Ann. Hum. Genet. 13: 211-222. GUREVITCH, J., HASSON, E., MARGOLIS, E. AND PULISHUK, Z. 1954. Blood groups in Jews from Cochin, India. Ann. Hum. Genet. 19: 254-256. HARRIS, H.A., AND KALMUS, H. 1949. The measurement of taste sensitivity to phenylthiourea (PTC). Ann. Hum. Genet. 15: 24-31. HELLER, H., GAFNi J., PRASS, M., AND SOHAR, E. 1960. Febbre Mediterranean fainil- iaire (FMF). Acta Genet. Med. (Rome) 3: 344-360. KALMUS, H. 1957. Defective colour vision, PTC tasting and drepanocytosis in sample from fifteen Brazilian populations. Ann. Hum. Genet. 21: 313-317. KALMUS, H. 1958. Improvements in the classification of the taste genotypes. Ann. Hum. Genet. 22: 222-239. MOTULSKY, A.G. 1960. Metabolic polymorphisms and the role of infectious diseases in human evolution. Hum Biol. 32: 28-62. MOURANT, A.E., KOPEC, A.C., AND DOMANIEWSKI-SOBEZAK, K. 1958. The ABO blood groups: Comprehensive tables and maps of world distribution. Oxford. PARR, L. W. 1934. Taste blindness and race. J. Heredity 25: 187-190. SACHS, L., AND BAT-MIRIAM, M. 1957. The genetics of Jewish populations. 1. Finger print patterns in Jewish populations in Israel. Amer. J. Hum. Genet. 9: 117-126. SALDANAH, P. H. 1958. Taste threshold for phenylthiourea among Japanese. Ann Hum. Genet. 22: 380-384. SHEBA ET AL. 51

SALDANAH, P., AND BECAK, W. 1959. Taste threshold for phenylthiourea among Ash- kenazic Jews. Science 129: 150-151. SZEINBERG, A., SHEBA, C., AND ADAM, A. 1958. Selective occurrence of glutathione in- stability in red blood corpuscles of the various Jewish tribes. Blood 13: 1043-1053. SZEINBERG, A., SHEBA, C., ADAM, A., AND RAMOT, B. 1959. A hereditary abnormality of the metabolism of glutathione in red blood cells. Symposium Genet. Haemet. Rome. Acta Genet. Med. Gemel. Suppl. Secundum. 1: 151-157. THAMBIPILLAI, V. 1956. Taste threshold for phenylthiourea in Malay school children. Ann. Hum. Genet. 20: 232-238.