HLA-DQA1/B1 alleles as putative susceptibility markers in congenital toxoplasmosis

Figures & data

Table 1. Distribution of the two groups (with toxoplasmosis and without toxoplasmosis - control) according to the ethnicity, demographic, social and economic characteristics and other parameters that are of interest in the context of toxoplasmosis.

Variable		Toxoplasmosis N=122 (%)	Control group N=103 (%)	p value^*
Maternal age (years)	< 20	23 (18.8)	21 (20.4)	0.965
	20-29	65 (53.3)	56 (54.4)
	30-34	20 (16.4)	16 (15.5)
	≥ 35	14 (11.5)	10 (9.7)
Mother's skin color	White	56 (45.9)	46 (44.6)	0.937
	Mixed-ethnicity^a	47 (38.5)	42 (40.8)
	Black	19 (15.6)	15 (14.6)
Newborn's skin color	White	55 (45.1)	46 (44.6)	0.966
	Mixed-ethnicity^a	48 (39.3)	42 (40.8)
	Black	19 (15.6)	15 (14.6)
Maternal education (years)	0-4	56 (46)	43 (41.8)	0.325
	5-8	64 (52.4)	60 (58.2)
	9-11	2 (1.6)	0 (0)
Family income (quartiles)^b	≤ 1 (lowest)	74 (60.6)	65 (63.1)	0.865
	2	46 (37.7)	37 (35.9)
	3	2 (1.7)	1 (1)
Parity	None	65 (53.3)	53 (51.5)	0.823
	1	49 (40.2)	41 (39.8)
	2	8 (6.5)	9 (8.7)
Prenatal care^c	Yes	98 (80.3)	103 (100)	< 0.0001
	No	24 (19.7)	0 (0)
Delivery	Vaginal	78 (64)	60 (58.2)	0.383
	Cesarean	44 (36)	43 (41.8)
Gestational age^d	Preterm	22 (18)	0 (0)	< 0.0001
	Full term	100 (82)	103 (100)
Birth weight (Kg)	>3	50(40.1)	75 (72.8)	< 0.0001
	2.5 – 3	58 (47.5)	26 (25.2)
	< 2.5	14 (11.5)	2 (1.9)
Household contact with animals^e	Yes	55 (45.1)	50 (48.5)	0.604
	No	67 (54.9)	53 (51.5)
Consumption of meat per week	1	35 (28.7)	23 (22.3)	0.493
	2	49 (40.2)	48 (46.6)
	3	38 (31.1)	32 (31.1)
Ingestion of raw or undercook meat	Yes	18 (14.7)	17 (16.5)	0.718
	No	104 (85.3)	86 (83.5)

^a Mixed ethnicity refers to a mixture of black and white;

^b The family income was divided into quartiles according to the Brazilian minimum wage (1 minimum wage = U$240 American dollars);

^c Prenatal care: yes refers to > 3 prenatal care appointments; No refers to no prenatal care at all or < 3 appointments;

^d Gestational age: preterm < 37 weeks and full term 37- 40 weeks (gestational ages were estimated at birth by the last menstrual period, the ultrasound performed at 21– 28 weeks, the ultrasound at 29 weeks and the method of Capurro, even in preterm infants;¹⁷

^e Household contact with animals refers mainly to cats and dogs;

* p value was calculated using (χ²) test or the Fisher's exact test was used when the cell counts were < 5.

Table 2. Description of the 10 alleles investigated in the HLA-DQA1 region, the number of alleles and the allele frequency in the 122 fetuses with congenital toxoplasmosis (study group) and in the 103 fetuses of the control group.

	N° of alleles		Allele frequency
DQA1 Alleles	Control group	Study group	Control group	Study group	OR (95% CI)	Bonferroni p < 0.005
*01:01	12	17	5.8	7.0	1.21 (0.56 – 2.59)	0.702
*01:02	37	22	18.0	9.0	0.45 (0.25 – 0.79)	0.0073
*01:03	16	50	7.8	20.5	3.06 (1.68 – 5.56)	0.0002
*01:04	19	9	9.2	3.7	0.37 (0.16 – 0.85)	0.018
*02:01	25	12	12.1	4.9	0.37 (0.18 – 0.76 )	0.005
*03:01	29	24	14.1	9.8	0.66 (0.37 – 1.18)	0.187
*03:02	2	21	1.0	8.6	9.60 (2.22 – 41.49)	0.0001
*04:01	16	28	7.8	11.5	1.53 (0.80-2.93)	0.205
*05:01	48	53	23.3	21.7	0.91 (0.58 – 1.42)	0.734
*06:01	2	8	1.0	3.3	3.45 (0.72 – 16.47)	0.118
Total	206	244	100	100	–	–

OR: odds ratio; CI: confidence interval; Bonferroni correction was calculated considering significant

p value 0.05/10 combinations of DQA1 alleles. The alleles presented in bold could confer susceptibility to congenital toxoplasmosis.

Table 3. Description of the five loci and 12 alleles investigated in the HLA-DQB1 region, the number of alleles in each group and the allele frequency in the 122 fetuses with congenital toxoplasmosis (study group) and in the 103 fetuses of the control group.

	N° of alleles		Allele frequency
DQB1 Alleles	Control group	Study group	Control group	Study group	OR (95% CI)	Bonferroni p < 0.0041
^*02:01	22	20	10.7	8.2	0.74 (0.39-1.41)	0.417
^*03:01	33	23	16.0	9.4	0.54 (0.30-0.96)	0.044
^*03:02	5	8	2.4	3.3	1.36 (0.43-4.23)	0.779
^*03:03	6	5	2.9	2.1	0.69 (0.20-2.32)	0.559
^*03:04	3	7	1.4	2.9	1.99 (0.51-7.83)	0.356
^*04:01	2	2	0.9	0.8	0.84 (0.11-6.04)	1.000
^*04:02	13	12	6.3	4.9	0.76 (0.34-1.72)	0.542
^*05:01	26	22	12.6	9.0	0.68 (0.37-1.25)	0.224
^*05:02	2	7	0.9	2.9	3.01 (0.61-14.67)	0.189
^*05:03	22	14	10.7	5.7	0.50 (0.25-1.02)	0.057
^*05:04	5	36	2.4	14.7	6.95 (2.67-18.09)	<0.0001
^*06^§	67	88	32.5	36.1	1.17 (0.79-1.73)	0.485
Total	206	244	100	100	–	–

Notes. Due to a high ambiguity, the frequencies of the

* 06 alleles were not discriminated, and the results were expressed as the total number of alleles at the *06 locus.

OR: odds ratio; CI: confidence interval; Bonferroni correction was calculated considering significant p values of 0.05/12 combinations of DQB1 alleles. The allele presented in bold could confer susceptibility to toxoplasmosis

^§ Due to a high ambiguity, the frequencies of the

Table 4. The number of cases in each group carrying the susceptibility haplotypes in the HLA-DQA1 and -DQB1 regions.

Susceptibility haplotypes	Study group	Control group	OR (CI - 95%)	Bonferroni p<0.005
Cases/total (%)	10/122 (8.20)	1/103 (0.97)	9.37 (1.17-74.54)	0.011

OR: odds ratio; CI: confidence interval; Bonferroni correction was calculated considering significant p value 0.05/9 combinations of DQA1and DQB1 haplotypes.

Pereira AP, Dias MA, Bastos MH, da Gama SG, Leal Mdo C. Determining gestational age for public health care users in Brazil: comparison of methods and algorithm creation. BMC Res Notes 2013; 6:60; PMID:23402277; http://dx.doi.org/10.1186/1756-0500-6-60

 PubMedGoogle Scholar