Prevalence and gene frequencies of phenylthiocarbamide (PTC) taste sensitivity, ABO and Rhesus factor (Rh) blood groups, and haemoglobin variants among a Nigerian population

Abstract

Background: Blood groups and phenylthiocarbamide (PTC) are the most studied genetic traits among human populations around the world. In most of these studies, PTC taste sensitivity was described as a bimodal autosomal trait inherited in a simple Mendelian recessive pattern.
ABO blood group is the most studied blood groups followed by Rhesus factors (Rh) and haemoglobin variants. Information from the study of these traits is useful to biologists, geneticists, anthropologists and clinicians. No information on the prevalence and gene frequencies of these
traits among a population from Nigeria.

Aim: This study presents information on the prevalence and gene frequencies of PTC taste sensitivity, ABO blood group and Rhesus factor, and Haemoglobin variants from male and female Nigerians
examined.
Subjects and methods: A total of 232 (51.33%) male and 220 (48.67%) female Nigerians participated in this study. Filter paper impregnated with 81.25 mg/L of saturated solution of PTC wasused to determine PTC tasters, while blood group phenotypes, Rhesus factor and haemoglobin
types were determined by classical method. Hardy–Weinberg method was used to determine allelic frequencies and graphpad 5 computer software was used for the data processing.

Results: The percentage frequency for non tasters of PTC was 29.42% with allele frequency t= 0.5424. There were more male (33.62%) non tasters than female (25.0%), but more female (75.0%) tasters than male (66.38%). This observation was statistically significant (p= 0.0444).
Our findings support the bimodal inheritance of PTC taste sensitivity among Nigerians. Overall trend of ABO blood group was O > B >A > AB. This same trend was observed for females but differed for males (O> B = A> AB). O blood group was the highest while AB group was the least among studied Nigerians in both genders. The distribution pattern did not differ significantly (p= 0.1406) from those expected under Hardy–Weinberg Law. 93.14% of the studied population was Rh+ (DD and Dd) and there were more Rh+ males than females but more Rh females than males. The proportions and distributions of Rh factor among
studied population did not show statistical significance (X2= 0.6047, df = 1, P = 0.4624). The overall allele frequency of the blood group as computed according to Hardy–Weinberg Law is r = 0.8201, q= 0.0977 and p= 0.0822. Similar trend in allele frequency was observed for both genders. The allele frequency for Rh+ (D) is 0.7381 and Rh (d)= 0.2619. This trend is also similar in both sexes. Among the six haemoglobin variants common to Nigerians CC was not detected in our study. The other five were observed in the order AA (76.55%)> AS (20.35%)> AC (1.99%) > SS (0.66%) >SC (0.44%). The overall allele frequency was A =0.8772, S =0.1106, C = 0.0122.

Conclusion: The findings from this study provide information on the studied traits. It will provide background information for further studies and will be useful to clinicians, geneticists and anthropologists with respect to blood transfusion, marriage counseling and population studies.