Am J Hum Genet 35:484-496, 1983

H-Deficient Groups of Reunion Island. II. Differences between Indians (Bombay Phenotype) and Whites (Reunion Phenotype) JACQUES LE PENDU,' GILBERT GERARD,2 DIDIER VITRAC,3 GENEVIEVE JUSZCZAK,4 GENEVIEVE LIBERGE,4 PHILIPPE ROUGER, CHARLES SALMON,4 FRANCINE LAMBERT,' ANNE-MARIE DALIX,' AND RAFAEL ORIOL'

SUMMARY Two variants of recessive, H-deficient nonsecretor individuals (h/h, sel se) were identified on Reunion Island: (1) H-negative individuals cor- responding to the classical Bombay phenotypes (Oh0, OhA, OhB, OhAB) who lack completely the H antigen on their red cells; all of them were Indian and had strong anti-H reacting with normal 0 and Oh red cells from whites; and (2) H-weak individuals (Oh, Ah, Bh, ABh). This phenotype represented the majority (85%) of the H-deficient phenotypes on Reunion Island, and all of them were white. They had only a weak expression of the H antigen and showed small but detectable amounts of ABH antigens on their red cells. Their anti-H antibodies reacted with normal 0 erythrocytes, but failed to react with Oh red cells, regardless of the ethnic origin of the donor. They were all from the same geographical area on the Island (Cilaos) and showed homogeneous titers of anti-H antibodies in sera. We propose to call this particular variant of weak H phenotype, belonging to the so-called para-Bombay series, Reunion.

INTRODUCTION Two main types of recessive H-deficient red cell phenotypes may be defined according to the genetic model [1] proposing that Se and H are closely linked structural genes: (1) the nonsecretor classical Bombay type (h/h, selse) [2], H- Received June 8, 1982; revised July 13, 1982. This study was supported by CRL 811043, INSERM U20 and U76, and CNRS LA 143. Institut d'Immuno-Biologie, HFpital Broussais, 75674 Paris Cedex 14, France. 2 Centre de Transfusion, H6pital Bellepierre, 97405 St-Denis, La R6union. Poste de Transfusion, H6pital St-Pierre, 97448 St-Pierre, La Rdunion. 4 CNTS, H6pital St-Antoine, 75571 Paris Cedex 12, France. C 1983 by the American Society of Human Genetics. All rights reserved. 0002-9297/83/3503-0013$02.00 484 H-DEFICIENT BLOOD GROUPS 485 deficient for both red cells and saliva, and (2) the secretor Bombay type with normal ABH in secretions but H-deficient for erythrocytes (h/h, Sel-) [3]. Bombay nonsecretors, the first type, have been shown to be heterogeneous [4, 5]. Some lack the H antigen completely. They have normal A or B enzymes in sera according to their ABO genotype OhA, OhB, OhAB), but their apparent red cell phenotype is always 0h. Other H-deficient individuals have only a weak expression of H. They have small amounts of H on erythrocytes that are transformed into A or B antigens and can be detected by direct agglutination or fixation-elution tests in A, B, or AB individuals and, consequently, have Ah, Bh, or ABh phenotypes. Although, theoretically, Oh with 0/0 genotype and weak expression of H should have small amounts of H and should be different from the 0h with complete lack of H, the difference between these two variants of Oh is difficult to ascertain. In practice, the heterogeneity of Oh phenotypes suggests that several weak alleles of H [6, 7] might exist, and therefore the H-h system could have a large quantitative polymorphism instead of the dimorphic H-h model classically accepted (reviewed in [8]). In accordance with this concept, Moores et al. [9] proposed the existence of at least two kinds of Oh phenotypes, since the 0h individuals from the Indian community of Natal were completely negative for ABH antigens, even with the most sensitive adsorption-elution tests. This was in contrast to other European reports showing some 0h phenotypes to have small amounts of erythrocyte ABH antigens detectable only by adsorption-elution tests [10-12]. The existence of the H-deficient phenotype on Reunion Island has been known for more than 10 years [13, 14], and a series of 42 H-deficient nonsecretor individuals has been reported recently [15]. The great majority of these phenotypes belong to the so-called para-Bombay group (Ah, Bh, and ABh). However, more detailed family studies described here suggest that at least three 0h individuals had normal A and/or B enzymes in sera but did not have detectable A and/or B antigens on red cells and were, consequently, OhA, OhB, and OhAB, respectively. Thus, two variants with complete and partial suppression for the expression of ABH antigens on red cells can be distinguished among the recessive H-deficient nonsecretor phenotypes of Reunion Island. Furthermore, quantitative analysis of ABH antigens on red cells and the reactivity of their anti-H antibodies showed a new and unexpected association between the amount of H antigen expressed on red cells and the ethnic origins (Indian or white) of the H-deficient individuals from Reunion Island. Indian H-deficient individuals were completely negative for the H antigen, while white H-deficient individuals had a weak, but positive, H antigen. In addition, the small amounts of H antigen produced by these white, weak H phenotypes were recognized by the anti-H antibodies of the H-deficient Indian individuals. MATERIALS AND METHODS The main reagents used for blood typing of the H-deficient subjects and their families were: Plant lectins Ulex europaeus whole extract was obtained from CNTS (Paris, France); Ulex europaeus lectin 1, purified by affinity chromatography, was obtained from Pharmindustrie IBF 486 LE PENDU ET AL. (Villeneuve-la-Garenne, France); Dolichos biflorus whole extract was obtained from CNTS; Bandeiraea simplicifolia lectin 1, purified by affinity chromatography, was obtained from E-Y Laboratories (San Mateo, Calif.). Animal Reagents Eel sera (anti-H), Helix pomatia extract (anti-A), and sheep hyperimmunized sera (anti- B) were obtained from CNTS. Human Antisera Human anti-A, and anti-B, and anti A+B were of immune origin and provided by CNTS. Anti-AI was obtained from an A2B individual. They were identified with the first four letters of the blood donor's surname. Papain Treatment of Erythrocytes One vol of washed red cells was incubated for 7 min with 1 vol of papain solution (Prolabo, Paris, France) in phosphate-buffered saline containing 1 mg/ml of cysteine [16]. Agglutination Tests were performed with native red cells (tests for identification of A,, A2, B, and H antigens) or papain-treated red cells (tests with sera of Oh donors). In each case, the tubes with 50 ,Il of the twofold serial dilutions of the reagents were incubated with 50 RIJ of a 5% suspension of erythrocytes for 1 hr at room temperature (20'C + 20C). The microag- glutination was observed with a microscope, and results were expressed in terms of cu- mulative scores ( + ++ = 10, + + = 8, + = 5, (+) = 2, - = 0) [16]. Immunoadsorbents Synthetic H type 1 and H type 2 trisaccharides bound to a solid matrix of crystalline silica were obtained from Chembiomed (University of Alberta, Edmonton, Canada). Glycosyltransferase Activity in Sera The A and B enzymes were measured by incorporation of N-acetyl [14C] galactosamine and [14C] on 2'-fucosylactose, respectively [17, 18]. A1 and A2 enzymes can be distinguished by their isoelectric points [19] and by their optimum pH activity [17]. The ratio of A-enzyme activity at pH 6.0 and pH 7.0 was used to determine the A, or A2 character of the A enzyme present in sera of two H-deficient individuals (see legends of figs. 4 and 5).

RESULTS White Pedigrees Forty-two H-deficient nonsecretor individuals, belonging to 25 different ped- igrees, were found on Reunion [15]. Twenty-one of these 25 families (85%) were white, and H-deficient individuals with at least one A and B gene expressed small amounts of the corresponding A or B antigens on their red cells (i.e., the two largest pedigrees of this series had two Ah, three Bh, and two ABh individuals [15]. Other examples of Reunion H-deficient white pedigrees are shown in figures 1-3. The CAD. family (fig. 1) has three H-deficient siblings, but the proposita (11-8) is Oh while her two H-deficient sibs (II-4 and II-10) are Bh. The sera of II- 8 had no glycosyltransferase activity, confirming that she had inherited 0 genes H-DEFICIENT BLOOD GROUPS 487 I. 1 20

0 Se Le

II. 1 2 3 4 5 6 7 8 9 10 11 12 13

l 6 6 6 -{ 6 B B Bh B 0 °h B Bh B B Se Se se Se Se Se se se se Se Se Le Le Le Le Le Le Le Le Le Le Le

III. 1 2 3 4 5 6 7 8 9 10 11 12 1314 15 16 17 18 19 20 21

B OO O O B OO B B O0O B 00 0 Se so Se se se Se se Se se Se se se se se se se se se se Le Le Le Le Le Le Le Le Le Le le Le le le Le Le le Le Le FIG. 1.-CAD. pedigree. White with weak expression of H antigen. Three H-deficient siblings were found (II-4, -8, -10). Erythrocytes of II-4 and 11-10 were agglutinated by anti-B (table 1), and normal B glycosyltransferase activity was found in their sera. Erythrocytes of II-8 were not agglutinated by anti-B, and there was no B glycosyltransferase in her serum. Offspring of II-8 x II-9 were nonsecretors (selse) as predicted by model proposed in [1]. Parents of 1-2 were cousins (degree not specified). A,, A2, B, and 0 = red cell phenotypes; Se = secretor phenotype; se = nonsecretor phenotype; Le = Le(a + b-) or Le(a-b + ) red cells and Leb and/or Le' saliva; le = Le(a-b-) red cells and Lewis negative saliva. Solid symbols (0, *): homozygous h/h genotype (Reunion h variant). Half-solid symbols (O, 0): assumed to be heterozygous Hlh genotype (Reunion h variant). from both parents and she has 0/0 genotype like her normal 0 sister 11-7. On the contrary, the other two H-deficient siblings must have received a B gene from their father, and they have B10 genotype like their normal B siblings (II-1, -3, -6, -11, -13). Seven out of the 21 white pedigrees had Oh phenotypes, and all of these Oh individuals seemed to have the 0/0 genotype since they did not have A or B

I. 1 2 A seOh Se Le Le II. 1 2 3I 4 5

0 A A A Se Se Se Se Le Le Le Le FIG. 2.-DIJ. pedigree. White with weak expression of H antigen. Erythrocytes of proband I-1 were not agglutinated by anti-A or anti-B (table 1), and his serum did not show either A or B glycosyltransferase activity. Symbols for ABO, Lewis, and secretor phenotypes and H genotypes as in figure 1. 488 LE PENDU ET AL. I. 1 2

0 0 Se se Le le

11. 1 2 3 4 5 6 7 8 9 S () L'I ]bS Oh Oh 0 0 0 0 0 Oh se se se Se se Se Se se Le Le Le Le le Le le Le FIG. 3.-HOA. pedigree. White with weak expression of H antigen. No A or B glycosyltransferase activity was detected in sera of the three H-deficient siblings (II- 1, -3, -9). Symbols for ABO, Lewis, and secretor phenotypes and H genotypes as in figure 1. glycosyltransferase activity in their sera: for example, the father I-I from the DIJ. pedigree must have 0/0 genotype because he does not have A or B enzymes in his serum (fig. 2). In addition, some had blood group 0 parents like the HOA. pedigree (fig. 3). In this family, it is evident that the three Oh siblings (11-1, II- 3, and 11-9) must have 0/0 genotype since both parents are 0. Indian Pedigrees Eight H-deficient individuals were identified in the four Indian pedigrees found on Reunion, and all eight had Oh phenotype. This is in contrast to the white H- deficient individuals who had a normal distribution of Ah, Bh, ABh, and Oh phe- notypes [15]. Segregation analysis of the Indian pedigrees showed that they are, in fact, different from the white pedigrees. The SEL. family (fig. 4) showed that the Oh proband 11-6 had transmitted the A allele, received from her mother (1-2), to her daughter (111-4), and therefore she must have AI0 genotype. The complete absence of A antigen on her red cells should be secondary to the complete lack of expression of H antigen, and her real phenotype is OhA. This was confirmed by the presence of a normal A2 enzyme in the sera of the proband (11-6). Her two Oh sisters (II- 13 and 11-15), on the contrary, did not show A glycosyltransferase activity in their sera, suggesting that they have 0/0 genotype. The BAR. family (fig. 5) showed two Oh phenotypes (11-8 and II-12). However, the 10 normal siblings tested were B, suggesting that the father (l- 1) is BIB. Four out of the 10 normal siblings were A2B, suggesting that the mother (1-2) is A2/ 0. Consequently, the most probable ABO genotypes for the two Oh siblings would be 0/B or A2/B. The determination of A and B enzymes in their sera showed normal A2 and B glycosyltransferase activity in the proband (11-8) and normal B glycosyltransferase in her H-deficient brother (II-12), showing that they are OhA2B and OhB, respectively. The two Oh siblings of the third Indian pedigree (RAM., fig. 6) could be 0/B or 0/0, but they did not show B glycoslytransferase activity in their sera, suggesting H-DEFICIENT BLOOD GROUPS 489

I.

I. 1 2 3 4 13 14 15 16 17

h 2 2 h 2 2 2 h Se se se Se se Se se se le le Le le Le le le le le le le le

III. 1 2 3 4 5 6 7

O 0 B A B se Se se Se Se se Le Le Le le Le Le

FIG. 4.-SEL. pedigree. Indian completely lacking the H antigen. Three Oh siblings were found (11-6, -13, -15). Erythrocytes of 11-6 were not agglutinated by anti-A or anti-H (table 1), but her serum showed A2 glycosyltransferase (optimum activity at pH 6.0), suggesting that she received an A2 gene from her mother 1-2 and transmitted it to her daughter III-4. Erythrocytes of II-13 and II-15 were not agglutinated by anti-A or anti-H (table 1), and they had no A glycosyltransferase activity in sera. 1-1 and 1-2 are first cousins. ABO, Lewis, and secretor phenotype as in figure 1. Solid symbols (0, *): homozygous h/h genotypes (Bombay h variant). Half-solid symbols (O, 0): assumed to be heterozygous Hlh genotypes (Bombay h variant). that they must have the 0/0 genotype, as do their two normal 0 siblings 11-6 and 11-7. The propositus of the fourth Indian pedigree was also Oh; unfortunately, she refused family and enzyme studies. Therefore, we cannot know the real ABO genotype of this particular Oh individual.

I. 1 2 B A2 se Se Le Le

1. 1 2 3 4 5 6 7 8 9 10 11 12 13 14

B A B B B B BA2B B A2B oB A2B B 2 h 2 2 h 2 Se Se se se Se se Se Se Se se Se Se Le Le Le Le Le Le Le Le Le Le Le Le

FIG. 5.-BAR. pedigree. Indian completely lacking the H antigen. Two Oh siblings were found. Their erythrocytes were not agglutinated by A, B, or H reagents, but serum of the proband II-8 had normal A2 (optimum activity at pH 6.0) and B glycosyltransferase activities, and serum of the I-12 had normal B glycosyltransferase activity. Therefore, their true phenotypes are assumed to be OhA2B (table 1) and OhB, respectively. According to the ABO phenotypes of the offspring, ABO genotypes of the parents must be: I-1, BIB and I-2 A2/O. I-1 and I-2 are second cousins. Symbols for ABO, Lewis, and secretor phenotypes as in figure 1. Symbols for H genotypes as in figure 4. 490 LE PENDU ET AL. I. 1 2

0 B Se se Le Le

I.1 2 3 4 5 6 7

Oh B Oh B 0 0 se Se se se Se Se Le Le Le Le Le Le FIG. 6.-RAM. pedigree. Indian completely lacking the H antigen. Red cells of the two Oh siblings (II-2, -4) were not agglutinated by A, B, or H reagents (table 1), and their sera did not show B glycosyltransferase activity. Consequently, they are expected to be Oho. Mother (I-2) and father of the father (I-1) were first cousins. Symbols for ABO, Lewis, and secretor phenotypes as in figure 1. Symbols for H genotypes as in figure 4.

Quantitative Estimation ofABH Antigens in Erythrocytes of Reunion H-deficient Individuals Erythrocytes of H-deficient donors from Reunion Island were tested with different anti-A, -B, and -H reagents (table 1). Eel sera and the Ulex europaeus whole extract, the two reagents used in routine typing for H antigen at CNTS, did not agglutinate any of the H-deficient eryth- rocytes, regardless of their ethnic origin, confirming our previous report [15]. However, since these two anti-H reagents were also negative with the A, normal control, and relatively weak with the B normal control, a third and stronger anti- H reagent was tested: the purified lectin 1 from Ulex europaeus at a starting concentration of 1 mg/ml on papain-treated red cells [20]. This test made a clearcut difference between Indian 0h samples (completely negative) and white 0h samples from Reunion Island (positive but weaker than the normal 0 controls). It also showed a weak positive reaction with Ah phenotypes and a very weak but positive reaction with Bh phenotypes (table 1). The two anti-Al reagents Dolichos biflorus and a human anti-A, serum were negative with all the samples. However, three strong anti-A Helix pomatia and two human antisera showed positive agglutination reactions with Ah and ABh samples. The human anti A+B serum reacted with all Ah, Bh, and ABh samples and the three B reagents; Bandeiraea simplicifolia lectin 1, sheep anti-B, and a human immune anti-B serum reacted with Bh and ABh samples. The reactions of Ah, Bh, and ABh samples with their corresponding A and B reagents were always weaker than reactions of the normal A or B control erythrocytes, but they were clearly positive (table 1). Alloantibodies in Sera from 0h Donors Agglutinating Normal 0 Erythrocytes In addition to the natural A and/or B agglutinins present in normal sera, all H- deficient donors found on Reunion Island had antibodies reacting with normal 0 H-DEFICIENT BLOOD GROUPS 491

U

+ < L eCnOS ) v) en n e r n "o

0~~~~~~.

< ~~~~~,)CoC o oC) ° °> °> CD C)"t CD CO-Nsoooc>CD )

a 000000o 0000 0 0000 00 CD CD CD c

0~~~~~

<

cl-C~~ ~ ~ ~

l-~~~~~~~QE -j - - 0 C%.0 CI~~~~~~~~~~~~~0 -

Cl 00000~~00 0 0 0000 0 0 0 00 0 z~~~~ 0~~~~~~~~~~~~~~~~~ 492 LE PENDU ET AL. control erythrocytes. The sera from 0h Indian donors (sera 1-6, table 2) had stronger average scores (62 + 8) than did sera (7-14, table 2) from the white 0h donors (24 + 11), with the five control 0 erythrocytes tested (P < .001, t = 16). Serum no. 15 was not included in this cluster analysis because it came from an 0h donor with normal H antigen in secretions (expected to be h/h, Se/- according to the model proposed in [1]), and this phenotype usually does not show anti-H antibodies as can be seen in table 2.

Alloantibodies in Sera from 0h Donors Agglutinating 0h Erythrocytes Table 2 also shows the reactions of the 15 0h sera with erythrocytes of the same 15 0h donors. As expected, each antiserum was negative with the autologous cells (diagonal in table 2). However, cluster analysis showed two different reaction patterns: (1) sera from white Oh donors were negative with all the Oh red cells tested, regardless of the ethnic origin of the erythrocyte donor; (2) sera from Indian Oh donors were also negative with red cells from Indian Oh donors, but they showed positive reactions with red cells from Oh white donors. Quantitative analysis of these reactions showed the average scores of Oh eryth- rocytes from white Reunion donors (28 + 16) to be weaker than the average scores involving reactions of the same sera with 0 controls (62 + 8) (P < .0001, t = 10.2). The Oh erythrocytes from European white donors showed apparently lower average agglutination scores (9 + 11) than did the Oh erythrocytes of Reunion white donors (28 + 16). However, detailed analysis of this cluster (sera 1-6 with red cells 11-15 in table 2) showed it to be heterogeneous. Two red cells (donors 11 and 12) were OhAl and had almost negative scores. These two cells had weak but positive adsorption-elution tests for the A antigen. One Oh red cell (donor 14) was intermediate between the scores of Indian and white Oh phenotypes of Reunion Island, and two other Oh red cells (donors 13 and 15) had similar agglutination scores as the Oh red cells of white Reunion donors.

Specificity of the Alloantibodies Present in Reunion H-Deficient Individuals The results oftable 2 strongly suggest that the main specificity involved is anti-H. The absorption of the antibody activity of an Oh serum (SEL. 11-6) with synthetic H immunoadsorbents confirmed its anti-H specificity (table 3). However, the H type 2 immunoadsorbent was more efficient in removing the anti- H activity than was the H type 1 immunoadsorbent.

DISCUSSION All Reunion H-deficient pedigrees analyzed, until now, are compatible with the model that proposes that H and Se are two closely linked structural genes [1]. This model implies that the Se allele is fully expressed in H-deficient individuals and that H-deficient nonsecretors must have selse genotype. The CAD. family (fig. 1) is particularly interesting in this respect because both the proband (11-8) and her husband (11-9) are nonsecretors, and, as predicted by our model, all the tested children (111-13, -14, -16, -17, -18, -20, -21) were selse. H-DEFICIENT BLOOD GROUPS 493

o 0 0 0 0 0 0 0 0 0) o 0 o 0 0 0 0 0 o 0 0 0 00 _ ^ 0 rr ~ r~l o o o o~~~~~~~~~~~~~~~~~~~~~~ 0 o o 0 0 0 0 0) 0 0D 0 00o (N - _ o~~ C o) o O C 0I o 0 0 0 0 0 rN 00 00 kfN 00

0: 0 0D 0: Nr eN) eN o o 0 0 0 0 C=)0 k(Nm LQ

0~H crO O O OC O O a)0 O O CD CD CD _ CD CD a) _n z 0.LU Oa 0 00 000C D0 00o (1n -

0 LL 2 0 0 o0o0o0o o o o o o oo0o o0000 N - ooo _~~ VU ---7 k) 0 0 0 0 0rO w N 00 00 kr) t1) 0 U) 00- LU 00 00 - - O) O - M M re) 00 - NI0- LU CL) -j -~ cI) 00 00 kr) 00 Cn N 0 0: 0 rm 0- 0 Lu 0 N (N 0 oo 00 0) CLI 'IC N- \O - r eN m ON~ 00 ON 'IC - 00 C "N- CIN eLI)Cm LI) ON

0- - - O- C)o f of)C 00 " o C( e- 1 - 00 - 'IC adH Nl z o o ooo - 2. m "t trI LQ 0 , ON V)0 z0 N ac) zLQ 00o N 00 ON 0 'IC 00 04 C13 00 ./ Z o o o o o CL. z =3 0 .... 0 0 0 .... oj z Ln .... (A 0 '3 0 o o o ooo *. -r- r- -o 0 z U 0 0 O 0 0 0. . C: u u u u -E 10< u o0 C; c 0 .r_ .r- ob 0. .-:2 0 LI- :3 LI.. I )

=3C 0 z jl OI_ 494 LE PENDU ET AL. TABLE 3 AGGLUTINATION SCORES OF ANTI-H SERA FROM AN Oh DONOR (SEL.V.) BEFORE AND AFTER ABSORPTION WITH SYNTHETIC H TYPE 1 AND H TYPE 2 IMMUNOADSORBENTS

Supernatant after Supernatant after Supernatant after adsorption adsorption adsorption Erythrocytes Original sera on H type 1 on H type I and H type 2 on H type 2

O control ...... 48 31 0 0 O control ...... 46 25 0 0 OhHOA.J 13 0 0 0

Our present study documents the existence of two variants of recessive nonse- cretor H-deficient phenotypes on Reunion Island: (1) A small proportion (about 15%) are Indian, lack the H antigen completely, and show no detectable A or B antigens on their red cells. This variant has strong anti-H antibodies that react with normal 0 and white Oh red cells. All the properties of these H-deficient phenotypes suggest that they belong to the classical Bombay series, which lacks completely the H antigen (Oh0, OhA, OhB, OhAl). (2) The majority of H-deficient individuals (about 85%) are white, have a weak expression of H, and small amounts of A, B, and H antigens can be detected on their red cells. This variant has anti-H antibodies reacting only with red cells of normal 0 donors. The partial expression of H, in H-deficient whites from Reunion, suggests that this variant belongs to the so-called para-Bombay series (Ah, Bh, ABh). However, in our opinion, the term para-Bombay is not precise enough. It has been used only for Ah, Bh, and ABh with exclusion of Oh phenotypes, while the present results clearly show that the white 0h of Reunion Island belong to the same group, with weak expression of H, and are different from the Indian Oh with complete lack of H. In addition, the notation of para-Bombay has been used for both secretors and nonsecretors in a nonuniform way by different authors [6]. In fact, the term para- Bombay was created to stress that some H-deficient variants were different from the original H-deficient variant described in the city of Bombay [2], but it does not imply that there are restrictions for the or the ethnic group of the subject. In addition to the 35 nonsecretor, H-deficient whites with weak expression of H found on Reunion, other Ah, Bh, or ABh nonsecretor individuals have been reported in Czechoslovakia [21], Greece [22], Canada [23], England [24], and France [5], and they all were whites, while all of the large series of H-deficient phenotypes that lack the H antigen completely, found in Natal [25], were Indians, as were all Reunion H-deficient phenotypes that lack the H antigen completely. The four Indian Reunion families did not have any ancestors from the Cilaos area while almost all of the white Reunion H-deficient families could be traced back to this small amphitheater on Reunion Island [15]. In addition to a common geographical origin, the figures from tables 1 and 2 clearly show that white H- deficient phenotypes from Reunion Island are quite homogeneous for both the amounts of ABH antigen expressed on red cells and the strengths of their anti- H antibodies. This is in contrast to the findings published involving European H-DEFICIENT BLOOD GROUPS 495 and Japanese H-deficient phenotypes [5] that show that they are heterogeneous, and, in particular, to the five European H-deficient individuals tested in the present study that also had variable amounts of H antigen. The present results suggest that the white H-deficient individuals of Reunion represent one particular variant of the H-deficient phenotypes due to inheritance in a double dose of a recessive H weak character. This weak H phenotype is distinct from some of the weak H phenotypes described in Europe and Japan and differs also from the Indian (Bombay) phenotype. We propose to call this particular white H-deficient phenotype Reunion. If the same genetic model proposed in [1] applies to all these H-deficient phenotypes, one should find nonsecretor and secretor individuals for Bombay, European, Japanese, and Reunion phenotypes. At least four such Indian Bombay secretor families have already been reported [3, 25]; some European [5] and Japanese [26, 27] H-deficient secretor phenotypes have also been reported, but no Reunion secretor phenotype has been found yet on Reunion Island. REFERENCES 1. ORIOL R, DANILOVS J, HAWKINS BR: A new genetic model proposing that the Se gene is a structural gene closely linked to the H gene. Am J Hum Genet 33:421-431, 1981 2. BHENDE YM, DESHPANDE CK, BHATIA HM, ET AL.: A "new" blood-group character related to the ABO system. Lancet 1:903-904, 1952 3. SOLOMON JM, WAGGONER R, LEYSHON WC: A quantitative immunogenetic study of gene suppression involving A, and H antigens of erythrocyte without affecting secreted blood group substances. The ABH phenotypes Am. and 0mb. Blood 25:470-485, 1965 4. SALMON C, CARTRON JP, ROUGER P, ET AL.: H deficient phenotypes: a proposed practical classification Bombay Ah, Hz, Hm. Blood Transfus Immunohematol 23:233- 248, 1980 5. SALMON C, CARTRON JP: The Hh blood group system, in Handbook Series in Clinical Laboratory Science Section D, Blood Banking vol 1, edited by GREENWALT TJ, STEANE EA, Cleveland, Ohio, CRC Press, 1977, pp 221-243 6. BHATIA HM: Serologic reactions of ABO and oh (Bombay) phenotypes due to variations in H antigens, in Human Blood Groups, edited by MOHN JR, PLUMKETT RW, CUN- NINGHAM RK, LAMBERT RM, Basel, Switzerland, Karger, 1977, pp 293-305 7. CARTRON JP: Biosynthese des antigenes de groupes sanguins humains, in XVth Congress of the International Society of , main lectures, Paris, Librarie Arnette, 1978, pp 69-86 8. WATKINS WM: Biochemistry and genetics of the ABO, Lewis and P blood group systems. Adv Hum Genet 10: 1-136, 1980 9. MOORES PP, ISSITT PD, PAVONE BG, McKEEVER BG: Some observations on "Bombay" bloods, with comments on evidence for the existence of two different 0h phenotypes. Transfusion 15:237-243, 1975 10. LANSET S, ROPARTZ C, ROUSSEAU PY, GUERBERT Y, SALMON C: Une famille comportant les phenotypes Bombay O'" et OB. Transfusion (Paris) 9:255-263, 1966 11. DZIERKOWA-BORODEJ W, MEINHARD W, NESTOROWICZ S, PIR6G J: Successful elution of anti-A and certain anti-H reagents from two Bombay (O h) blood samples and investigation of isoagglutinins in their sera. Arch Immunol TherExp (Warsz) 20:841 - 849, 1972 12. RODIER L, LOPEZ M, LIBERGE G, BADET J, GERBAL A, SALMON C: Anti-H absorbed by and eluted from Oh (Bombay) red blood cells. Biomedicine 21:312-316, 1974 13. GERARD G, GUIMBRETIERE J, GUIMBRETIERE L: Difficultes de groupage chez un sujet vraisemblablement Ah. Rev Fr Transfus 13:267-274, 1970 496 LE PENDU ET AL. 14. LIBERGE G, SALMON C, GERBAL A, LOPEZ M: Le phenotype Bh. Rev Fr Transfus 13:357-363, 1970 15. GERARD G, VITRAC D, LE PENDU J, MULLER A, ORIOL R: H-deficient blood groups (Bombay) of Reunion Island. Am J Hum Genet 34:937-947, 1982 16. ROUGER P, SALMON C: Les epreuves d'agglutination, in La Pratique de l'Agglutination des Erythrocytes et du Test de Coombs, Paris, Masson, 1981, pp 31-35 17. CARTRON JP, ROPARS C, CALKOVSKA Z, SALMON C: Detection of AA2 and A2AmA1 heterozygotes among human A blood group phenotypes. JImmunogenet 3:155-161, 1976 18. CARTRON JP, MULET C, BADET J: Use of two chemically synthesized H acceptors as substrates for A and B blood group gene-specified glycosyltransferases. FEBS Lett 67:143-148, 1976 19. TOPPING MD, WATKINS WM: Isoelectric points of the human blood group A', A2 and B gene-associated glycosyltransferases in ovarian cyst fluids and serum. Biochem Biophys Res Commun 64:89-96, 1975 20. DODD BE, LINCOLN PJ: Serological studies of the H activity of oh red cells with various anti-H reagents. Vox Sang 35:168-175, 1978 21. LEVINE P, UHLhI M, WHITE J: Ah, an incomplete suppression of A resembling 0h Vox Sang 6:561-567, 1961 22. 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