Recurrent extended HLA haplotypes in children with selective IgA deficiency

HLA supratypes as well as serum IgG, IgA and IgM levels were determined in 44 children and adolescents with severe IgA deficiency (serum IgA less than 5 mg/dl) and in first degree relatives. Frequencies of the HLA alleles B14, DR1, DQW1, C4A2 and C4B2 were significantly higher in the IgA-deficient patients than in the controls. The most recurrent haplotype among patients was B14, DR1 (p less than 10(-4) preferentially associated with A33, A28 or A blank. The supratype B14, Bfs, C4A2, C4B2, DR1, DQW1 was present in a 14-fold higher frequency than in the controls, and strongly suggests the presence of a gene in the HLA region involved in the deficiency of IgA. The fact that this supratype was not always associated with IgA deficiency in the parents and that not all IgA-deficient subjects had this supratype is discussed. Severe IgA deficiency was found in four mothers (two of the four mother-child pairs shared the B14, DR1 haplotype); three other relatives (one father and two brothers) had partial IgA deficiency and did not have the B14, DR1, DQW1 haplotype.

Immunoglobulin Allotypes in Familial Malignant Melanoma

There is some evidence that genes at loci on the lower end of chromosome 14, encoding for the immunoglobulin heavy chains allotypes (Gm), may influence susceptibility to human tumors. We examined the Gm and Km (IgK light chain) allotype distribution in a sample of 41 patients with familial malignant melanoma and in 79 healthy relatives. An increased frequency of the haplotype carrying the Gm (2) allotype, namely Gm (1, 2, 17;..; 21), seemed to be peculiar to patients, since it was almost twice as frequent in them than in the healthy population and four times as frequent with respect to the healthy relatives. Our findings are in keeping with previous suggestions that in Caucasian melanoma patients genes of the immunoglobulin heavy chain constant region, or Gm-linked genes, may enhance susceptibility to malignant melanoma.

Possible interaction between HLA and Ig light chain markers in susceptibility to uveitis

We detected and analysed the Gm and Km allotype markers of Ig in 57 patients affected by uveitis, an ocular inflammation with multifactorial etiology. The aim of the present study has been to investigate the possibility that different immunogenetic factors predispose to the various forms of the disease. We found a statistically significant alteration of Km(1) allele frequency (relative risk = 2.65). That seems to predispose to anterior uveitis, especially when associated with a blank at HLA-A locus (RR = 7.83) but predispose to the posterior form when in combination with HLA-B38 (RR = 19.24). Moreover, a high frequency of Km(1)/A blank phenotypic association was noticed in uveitis with infectious aetiology (RR rising to 10.44). The Km(1) genotype may itself predispose to uveitis and its combination with different HLA alleles could enhance the susceptibility to one particular form rather than to another.

Report of one case of familial sarcoidosis

Familial sarcoidosis is a quite unusual occurrence. We describe two affected sisters, in which the clinical features of the disease were fairly similar. Interestingly, the two patients and two unaffected siblings share an HLA haplotype [A10 (26); CW7; B16 (38); DRW6; DQW1] rare in Caucasians.

Italian extended HLA haplotypes in congenital adrenal hyperplasia

In order to complete the data on human 21-Hydroxylase deficiency, we present a study on HLA markers in 35 Italian families (14 from Northern, eight from Central and 13 from Southern Italy) with one affected child. Three children from the issue of first cousin marriages were homozygous for the whole HLA haplotype. Extended haplotypes shared by unrelated patients were not found, and a total absence of the HLA Bw47 allele among the haplotypes carrying the disease as well as normal haplotypes was observed. The absence of A1 Cw7 B8 BfS C4AQ0 C4B1 DR3 extended haplotype was instead confirmed. Allele frequencies in the different clinical forms were analyzed: BfSO7 allele frequency was significantly increased on haplotypes of the salt-wasting form (p less than 0.01). We noticed two duplications (C4B1-2) of C4B genes, on haplotypes involved in the disease. Allele distribution in the regions studied showed that Bw22 (w55), Cw3 and DR2 were characteristic of Northern patients, while B15 was found in patients from Central Italy.

C4A7: a new variant of human complement C4

A rare variant of complement C4 was found in 2 related individuals. It has the most anodic mobility found to date, no hemolytic activity detected by the overlay technique and a Bgl II RFLP pattern very similar to that of the C4A6 type.

Human MHC class III genes, BF and C4. Polymorphism, complotypes and HLA class I and II associations in the Lombardy population (Italy)

The polymorphisms of the fourth component of human serum complement and factor B (BF) (controlled by class III MHC genes) was investigated in a panel of 250 unrelated individuals from the Lombardy population, previously HLA typed (A, B, C, DR, DQ antigens) and in 25 families. Nine different alleles at the C4A and eight at the C4B loci were detected. At both loci, alleles without a gene product (i.e. "null alleles") were observed with high frequency: 8.2% for C4A "nulL" and 10% C4B "null". As expected from allele frequencies the most common haplotype was C4A*3, C4B*1 (52%). The most common BF alleles, BF*S and BF*F had a frequency of 77.7% and 17.7% respectively, while the gene frequencies of SO.7 and F1 were 2.9 and 0.9% respectively. The association of complotypes and HLA haplotypes was analysed in 50 chromosomes. The most common combination, defined by class I, II and III alleles was B35-S31-DR5 (11%) followed by B16(38)-S31-DR5 with a frequency of 6.5%. Two duplications at the C4B locus were detected. A new variant (C4A*X) strikingly faster than that of the C4A*6 product was identified in two related individuals (aunt and nephew). The practical advantages of complotype determination in disease association studies and in healthy population is discussed.

Human leukocyte antigen region involvement in the genetic predisposition to alopecia areata

Human leukocyte antigens (HLA) of classes I and II were studied in 127 patients with alopecia areata (AA). The patients were subdivided into different groups depending on hair loss area, sex, pathogenesis, response to topical immune modulators (squaric acid dibutylester and diphencyprone) and age of onset of the disease. The frequencies of class I HLA markers (loci A, B, C) were not significantly different from the controls. However, among the class II antigens (loci DR, DQ), the frequency of DR5 was increased in both alopecia areata and alopecia universalis when compared with the control group. In particular, DR5 was strongly linked to the early-onset form. The highest DR5 frequency (62%) was found in the group of patients which presented both the early onset and the most severe form of the disease (p less than 0.01; RR = 3.14). A decrease of the HLA-B8 phenotype frequency was found in the alopecia areata group versus the alopecia universalis one. No significant deviation was found between the female patients and the control group. However, an increase of CW3 and a decrease of DR1 was seen in the males. In the group including 'combined', 'prehypertensive', 'atopic' alopecia of Ikeda's classification the frequency of HLA-A28 and DR5 was increased and that of DR1 was decreased in comparison with the 'common' type of alopecia and the controls. It was not possible to find any relationship between these genetic markers and the response to topical immune modulators.

Genetic heterogeneity in uveitis

Eighty-nine unrelated patients with ocular inflammation (uveitis) were investigated for the HLA class I and class II genetic markers, We subdivided our patients according to: 1. the anatomical location of the lesion; 2. the temporal course of the disease; 3. the aetiology. We eliminated from our sample of patients the individuals with other systemic diseases. We could not find an association with B27, as previously described, but we did note statistically significant differences between the class II antigen distribution in the different anatomical subgroups. HLA-DR3 seems a marker of the intermediate form of uveitis (p, uncorrected 0.03); the absence of DR1 in the patient group with posterior uveitis may be a protecting factor (p. uncorrected less than 0.01); the presence of DR4 in all cases of panuveitis is statistically significant (p, uncorrected = 0.0006).