Search

Recessively inherited ovalocytosis in coastal Melanesians is associated with widespread, but selective, depression of blood group antigens in homozygotes, who comprise about 15% of these populations. It is suggested that a membrane anomaly exists, and that the series of depressed determinants all depend, for their full expression, upon the same membrane component(s), the proper synthesis of which is being genetically affected. Affected antigens would thus be associated by position and/or structure. Antigens subject to depression include IT, IF, LW,D,C,e,S,s,U,Kpb,JKa,JKb,Xga,Wrb,Scl and Ena, which are simultaneously affected when present on oval cells. Reactivity of A1,ID,i,P1,M,N,Lub,k,Fya,Coa, Vel and Gea appears to be within the normal range on depressed cells, as does sialic acid content. Indirect evidence suggests that Z (associated with S and s) is among the depressed series, while NA and Leb are not. High H variants, common among Melanesians, seem absent among depressed bloods, and when such variants were excluded, H, A and B did not appear subject to depression. The distribution pattern of ovalocytosis suggests that it may confer some selective advantage in the tropical coastal environment. The findings also have implications concerning population genetic work in New Guinea.

The results of blood group surveys on a number of linguistic groups inhabiting contiguous areas within the Goilala sub-district of the Central District, the southern part of the Morobe District and the Northern District are reported. Altogether about 1900 subjects were tested, but the extent of testing varied. Red cell enzyme and serum protein systems were also investigated in two groups. Similarities and dissimilarities of blood group distributions are noted, as also are some possible gene gradients among peoples living to the north of the main divide. Two groups, the Kuni/Tauade of the Goilala sub-district, and the Roro/Kovio living towards the Papuan Gulf coast seem well distinguished from the remainder. Genetic distances were calculated for five populations north of the divide, and agree with the geographical and linguistic situation. The Weri people of the middle Waria provided an example of Hp 2-1 modified, two examples of the MDH.NG.1 variant and one of AK 2-1.

A series of blood samples from four villages in the Jimi Valley, Western New Guinea Highlands, has been tested for genetic variation in blood group, serum protein, and red cell enzyme systems. Polymorphic variation was present for the AB0, MNS, P, and Rh blood group systems, for the Hp and Tf serum protein systems, and for the acid phosphatase, 6-PGD, PGM, MDH, and ADA enzyme systems. One each of the following variants was detected: Ge(a-), G6PD deficient, AK 2-1 and PHI 7-1 or 8-1. All samples tested were Cw-, K-, Kp(a-), Wr(a-), Fy(a+ b-), Rd-, and LDH normal. Genetic distance analysis places the Jimi Valley populations closer to peoples of the Chimbu-Chuave and Wahgi-Hagen areas than to the Maring people of the Simbai Valley to the north.

A distinctive type of hereditary ovalocytosis has been found in Papua New Guinea and a few areas of Southeast Asia. Its main features include a high incidence among tropical lowland dwellers, autosomal recessive inheritance, specific depression of a number of red cell antigens, a characteristic morphology in blood films, and an effect on the erythrocyte sedimentation rate. Speculation has occurred as to whether the high incidence of ovalocytosis in malarious areas may be related to a selective advantage possessed by ovalocytics with regard to severe malaria. Preliminary data tend to support this hypothesis, but the evidence is not conclusive and much further work is needed.