Autoimmunity, HLA, Gm and Km polymorphisms in Turner's syndrome

Hyperglycemia in Turner syndrome: Impact, mechanisms, and areas for future research

Turner syndrome (TS) is a common chromosomal disorder resulting from complete or partial absence of the second sex chromosome. Hyperglycemia, ranging from impaired glucose tolerance (IGT) to diabetes mellitus (DM), is common in TS. DM in individuals with TS is associated with an 11-fold excess in mortality. The reasons for the high prevalence of hyperglycemia in TS are not well understood even though this aspect of TS was initially reported almost 60 years ago. Karyotype, as a proxy for X chromosome (Xchr) gene dosage, has been associated with DM risk in TS - however, no specific Xchr genes or loci have been implicated in the TS hyperglycemia phenotype. The molecular genetic study of TS-related phenotypes is hampered by inability to design analyses based on familial segregation, as TS is a non-heritable genetic disorder. Mechanistic studies are confounded by a lack of adequate TS animal models, small and heterogenous study populations, and the use of medications that alter carbohydrate metabolism in the management of TS. This review summarizes and assesses existing data related to the physiological and genetic mechanisms hypothesized to underlie hyperglycemia in TS, concluding that insulin deficiency is an early defect intrinsic to TS that results in hyperglycemia. Diagnostic criteria and therapeutic options for treatment of hyperglycemia in TS are presented, while emphasizing the pitfalls and complexities of studying glucose metabolism and diagnosing hyperglycemia in the TS population.

Immunological Profile and Autoimmunity in Turner Syndrome

Turner syndrome (TS), characterized by the partial or complete absence of an X-chromosome, provides a unique insight into the role of the X-chromosome and the immune system. While women have a 10-fold higher incidence of autoimmune disease (AD) compared with men, the risk in women with TS is thought to be further doubled. TS is associated with a propensity for a wide variety of ADs that increase in incidence across the life span. Isochromosome Xq as well as isolated Xp deletion karyotypes may predispose to higher rates of AD in TS suggesting the impact of X-chromosome gene dosage. It is likely, however, that epigenetic changes across the genome and the hormonal milieu may also have a profound impact on the immune profile in TS. This review explores the immune phenotype and the spectrum of ADs in TS. Genotype-phenotype correlations are presented with a brief overview of the genetic and hormonal underpinnings.

Autoimmunity and Turner's syndrome

Turner Syndrome (TS) is a common genetic disorder, affecting female individuals, resulting from the partial or complete absence of one sex chromosome, and occurring in approximately 50 per 100,000 liveborn girls. TS is associated with reduced adult height and with gonadal dysgenesis, leading to insufficient circulating levels of female sex steroids and to infertility. Morbidity and mortality are increased in TS but average intellectual performance is within the normal range. TS is closely associated to the presence of autoantibodies and autoimmune diseases (AID), especially autoimmune thyroiditis and inflammatory bowel disease. Despite the fact that the strong association between TS and AID is well known and has been widely studied, the underlying immunopathogenic mechanism remains partially unexplained. Recent studies have displayed how TS patients do not show an excess of immunogenic risk markers. This is evocative for a higher responsibility of X-chromosome abnormalities in the development of AID, and particularly of X-genes involved in immune response. For instance, the long arm of the X chromosome hosts a MHC-locus, so the loss of that region may lead to a deficiency in immune regulation. Currently no firm guidelines for diagnosis exist. In conclusion, TS is a condition associated with a number of autoimmune manifestations. Individuals with TS need life-long medical attention. As a consequence of these findings, early diagnosis and regular screening for potential associated autoimmune conditions are essential in the medical follow-up of TS patients.

GM and KM immunoglobulin allotypes in the Galician population: new insights into the peopling of the Iberian Peninsula

Background

The current genetic structure of Iberian populations has presumably been affected by the complex orography of its territory, the different people and civilizations that settled there, its ancient and complex history, the diverse and persistent sociocultural patterns in its different regions, and also by the effects of the Iberian Peninsula representing a refugium area after the last glacial maximum. This paper presents the first data on GM and KM immunoglobulin allotypes in the Galician population and, thus, provides further insights into the extent of genetic diversity in populations settled in the geographic extremes of the Cantabrian region of northern Spain. Furthermore, the genetic relationships of Galicians with other European populations have been investigated.

Results

Galician population shows a genetic profile for GM haplotypes that is defined by the high presence of the European Mediterranean GM*3 23 5* haplotype, and the relatively high incidence of the African marker GM*1,17 23' 5*. Data based on comparisons between Galician and other Spanish populations (mainly from the north of the peninsula) reveal a poor correlation between geographic and genetic distances (r = 0.30, P = 0.105), a noticeable but variable genetic distances between Galician and Basque subpopulations, and a rather close genetic affinity between Galicia and Valencia, populations which are geographically separated by a long distance and have quite dissimilar cultures and histories. Interestingly, Galicia occupies a central position in the European genetic map, despite being geographically placed at one extreme of the European continent, while displaying a close genetic proximity to Portugal, a finding that is consistent with their shared histories over centuries.

Conclusion

These findings suggest that the population of Galicia is the result of a relatively balanced mixture of European populations or of the ancestral populations that gave rise to them. This would support the importance of the migratory movements that have taken place in Europe over the course of recent human history and their effects on the European genetic landscape.

Ankylosing spondylitis in a patient with Turner syndrome: a case report

Turner's syndrome (TS) is a chromosomal disorder where phenotypic females have either a missing chromosome (45 X0) or a structural aberration of one of the chromosomes. It is possible for TS to accompany such autoimmune diseases as thyroid diseases, inflammatory intestinal diseases, diabetes mellitus, psoriatic arthritis and juvenile rheumatoid arthritis. Herein, we present an unusual case with Ankylosing spondylitis (AS) and autoimmune thyroiditis associated with TS. We suggest that the possibility that TS patients may also develop such other diseases as AS apart from the already known accompanying autoimmune diseases should not be ruled out when monitoring TS patients.

Increased liver enzymes and hormonal therapies in girls and adolescents with Turner syndrome

Elevated liver enzymes can be seen relatively frequently in patients with Turner syndrome (TS), while the pathogenesis of this remains unclear. Our epidemiological and prospective study aimed to investigate: a) the natural 2-yr course of liver disease in a selected cohort of young patients with TS, who had been preliminarily recruited on the basis of persistently elevated liver enzymes; b) the role of prolonged hormonal therapies in the etiology of liver dysfunction. From an overall population of 214 TS patients younger than 20 yr, only 19 (8.9%) were recruited, according to the following inclusion criteria: increased serum concentrations of one or more liver enzymes, exceeding the uppermost limit of the respective normal ranges, and persistence of these liver alterations for 6 months after the preliminary assessment. On the basis of the results of this prospective study, we can conclude that: a) the prevalence of liver abnormalities in girls and adolescents with TS is much lower and more strictly related to hormonal therapies than in TS adults; b) both autoimmunity and obesity are not frequently involved in the etiology of TS liver dysfunction; c) liver damage is either mild or moderate and its severity is not conditioned by karyotype; d) its course may be self-limiting; e) its natural history may be characterized in some cases by a slight deterioration of intrahepatic cholestasis, with no negative repercussions on liver synthetic function.

Halo nevus, rather than vitiligo, is a typical dermatologic finding of Turner's syndrome: Clinical, genetic, and immunogenetic study in 72 patients

Turner's syndrome (TS) is a genetic disorder caused by numeric and/or structural abnormalities of the X chromosome; it is characterized by short stature, gonadal dysgenesis, and frequently by webbed neck, cubitus valgus, and lymphedema at birth. TS has been associated with several cutaneous abnormalities including an increased frequency of pigmented nevi, but few reports consider nevi in detail. Halo nevus (HN) is clinically defined as a melanocytic nevus surrounded by a halo of depigmentation. Vitiligo, a dermatologic disorder characterized by the presence of depigmented patches on the skin, has been described in the list of cutaneous findings associated with TS. The aim of this study was to determine the prevalence of HN and vitiligo in TS and to evaluate if a correlation between major histocompatibility complex genes, karyotype, autoimmunity, therapies, and the presence of HN exists. Of the 72 patients with TS examined, 13 had HN, a prevalence of 18.05%, which was significantly higher than in our control group (1%; P=.000001). On the contrary, only 2 patients with TS (2.77%, P=not significant) had vitiligo. By comparing the distribution of HLA class I alleles between patients with TS who did (13 of 72) and did not (59 of 72) have HN, we observed a significantly higher frequency of HLA-Cw6 in patients with TS and HN than in those without HN (26.92% vs 6.78%, respectively; P=.0067; odds ratio=5.06). The study of HLA class II genomic polymorphisms showed that the DRB1(*)0701 and DQB1*02 alleles for patients with TS and HN were overrepresented when compared with those without HN (34.61% vs 11.86%, respectively, P=.0078, odds ratio=3.93; and 34.61% vs 19.49%, respectively, P=.1386, odds ratio=2.19). In conclusion, this study is the first to demonstrate an increased prevalence of HN for patients with TS. Furthermore, the data suggest that a HN putative susceptibility gene in TS is located close to the HLA-C locus.

Turner's syndrome in dermatology

Turner's syndrome (TS) is a common genetic disorder of girls and women, for which the defining clinical triad is short stature, impaired sexual development, and infertility. Although classically known as monosomy X, genetic heterogeneity is frequent in TS, with mosaicism conferring a survival advantage. Several genetic loci have been implicated in TS including the short stature homeobox gene. TS effects many organs, with cutaneous stigmata providing critical clues for early detection of TS. The presence of lymphedema and its cutaneous sequelae are predictive of other systemic disorders, such as cardiac disease. Although an increased number of benign nevi have been reported in TS, the decreased melanoma rate in this population suggests some protective factor is active. Keloids were thought to be prevalent in TS, but recent data suggest otherwise. Autoimmune diseases are common in TS, with a possible increased prevalence of alopecia areata and vitiligo. The following review discusses new insights into the genetics and pathogenesis of this complex disorder, summarizes the major systemic effects, and reviews skin manifestations of TS and their implications.

Parental GM and HLA genotypes and reduced birth weight in patients with Turner's syndrome

We investigated a possible influence on birth weight in Turner's syndrome of many clinical, hormonal, genetic and immunogenetic variables. We considered 97 patients with Turner's syndrome. Patients with parents with identical GM (Gamma heavy chains Marker) phenotype had a significantly lower birth weight than those with parents with different GM phenotype. Karyotype other than 45,X, HLA (Human Leukocyte Antigen) parental sharing, mother-patient compatibility and elevated 17-hydroxyprogesterone (17OHP) serum level after adrenocorticotropin hormone (ACTH) and absence of heart and kidney malformations and lymphedema were associated with a lower birth weight, but not significantly. Multiple interactions showed that the presence of an identical GM phenotype in parents, together with other conditions (karyotype other than 45,X, adrenal dysfunction, HLA parental sharing, mother-child compatibility, KM(3) [Kappa light chains Marker] phenotype) resulted in a further decrease of birth weight. These data might suggest a negative effect of genetic similarity on intrauterine growth in Turner's syndrome.

Turner syndrome and the heart: cardiovascular complications and treatment strategies

Turner syndrome is a condition usually associated with reduced final height, gonadal dysgenesis, and thus insufficient circulating levels of female sex steroids, and infertility. A number of other signs and symptoms are seen more frequently with the syndrome. With respect to cardiac function, congenital malformations of the heart and the great vessels, hypertension and ischemic heart disease, and increased risk of aortic dissection are all conditions that the pediatrician or the physician caring for females with Turner syndrome should keep in mind. Many girls and adolescents with Turner syndrome receive growth hormone (GH) treatment, which has so far been an effective and well-tolerated therapy. Nevertheless, because of the experience from acromegaly, the physician should monitor blood pressure and perform echocardiography, together with clinical examinations by a cardiologist at regular intervals. During adulthood most women with Turner syndrome are faced with premature menopause and the need for female hormone replacement therapy (HRT). During clinical evaluation of girls and women with Turner syndrome, these conditions and complications should be kept under surveillance. Here the cardiovascular complications of Turner syndrome are reviewed. The risk of congenital heart defects such as bicuspid aortic valves, aortic coarctation, other valve abnormalities, and septal defect is increased. Likewise, the risk of aortic dissection at a young age is increased, as is the risk of hypertension, ischemic heart disease, and stroke. GH therapy does not seem to adversely affect the heart, although longer-term follow-up studies are needed. In short-term studies, HRT lowers blood pressure, while any effect on the risk of ischemic heart disease has not been evaluated. Treatment with GH and HRT are discussed in relation to the heart and great vessels. Presently, the pathophysiology of the congenital cardiovascular malformation in Turner syndrome is unexplained, although different theories exist. Recommendations for clinical practice are given, including life-long surveillance of cardiac function, aortic diameter and blood pressure.

Evidence of a normal mean telomere fragment length in patients with Ullrich-Turner syndrome

Clinical and epidemiological studies suggest that premature ageing and increased morbidity and mortality is present in Ullrich-Turner syndrome. We studied telomere restriction fragment length (TRFL) in 30 women with Ullrich-Turner syndrome and 30 age-matched control women. All Turner women had the 45,X karyotype verified by karyotyping. We found no difference in the mean TRFL in the young age group (TS: 7011+/-521 vs C: 7285+/-917 bp, P = 0.3), or in the older age group (TS: 7357+/-573 vs C: 7221+/-621 bp, P = 0.6). In conclusion, our data suggest that Ullrich-Turner syndrome is not associated with excessive telomere loss, at least when studied in peripheral blood leucocytes, and thus quite different from other premature ageing syndromes.

Aspects of the treatment of Turner syndrome

Several issues have to be considered when taking care of girls and women with Turner syndrome. During childhood, short stature is the primary concern and treatment with growth hormone (GH) is now widely used, often in conjunction with the androgen, oxandrolone. Recent studies indicate that doses used previously in the treatment of short stature have been too small. Induction of puberty should be performed at an appropriate age with reference to the peers of the patient. In adulthood, female sex hormone substitution should be offered to possibly prevent the increased morbidity seen in Turner syndrome, which consists of increased risk of fractures and osteoporosis, a clustering of diseases like ischaemic heart disease, hypertension, stroke and Type 2 diabetes, the latter entities being involved in the insulin resistance syndrome. Furthermore, hypothyreosis are often seen and the risk of Type 1 diabetes may also be increased. Congenital malformations of the heart are frequently seen in Turner syndrome, possibly increasing the risk of dissecting aorta aneurism. Liver enzymes are often elevated in Turner syndrome and there may be an increased risk of cirrhosis of the liver. Mortality does seem to be increased in Turner syndrome and women with the 'pure' 45,X karyotype do seem to be most severely affected. In the clinical practice of Turner syndrome, a careful monitoring of glucose and bone metabolism, weight, thyroid function and blood pressure should be performed. A cardiovascular risk profile should be determined and the patient informed concerning risks and benefits from sex hormone replacement therapy. Based on the available literature, sex hormone replacement therapy is highly recommended, although at present there are no longitudinal data documenting the long-term positive effect of sex steroid substitution. However, hypogonadism is expected to explain at least part of the decreased lifespan found in Turner syndrome. Since general physicians encounter Turner patients infrequently, it is recommended that the care and treatment of Turner syndrome is centralised.

Morbidity in Turner syndrome

Turner syndrome afflicts approximately 50 per 100,000 females and is characterized by retarded growth, gonadal dysgenesis, and infertility. Much attention has been focused on growth and growth promoting therapies, while less is known about the natural course of the syndrome, especially in adulthood. We undertook this study to assess the incidence of diseases relevant in the study of Turner syndrome. The study period was from January 1, 1984 to December 31, 1993, and the study base was all women living in Denmark during the study period. We used data from the Danish Cytogenetic Central Register and the Danish National Registry of Patients to assess morbidity. This study supports several earlier studies reporting increased morbidity and confirms results of a recent study on cancer in Turner syndrome. Women with Turner syndrome seem to have an increased incidence of fractures, osteoporotic fractures in adulthood, and non-osteoporotic fractures in childhood. Furthermore, diabetes mellitus, both NIDDM and IDDM, was found with a markedly increased incidence in Turner syndrome, as well as ischemic heart disease, hypertension, and stroke. The risk of cancer, except cancer of the large bowel, does not seem to be elevated in Turner syndrome. Our data suggest that patients with Turner syndrome are extraordinarily prone to abnormalities constituting the metabolic syndrome (e.g., hypertension, dyslipidaemia, NIDDM, obesity, hyperinsulinemia and hyperuricemia). The present data may help to explain the decreased life span found in patients with Turner syndrome.

Organ- and non-organ-specific auto-antibodies in children with hypopituitarism on growth hormone therapy

Serum non-organ-specific antibodies (NOSA) against nuclear, mitochondrial (AMA), smooth muscle, liver/kidney microsomal (LKM), reticulin, ribosomal, and organ-specific antibodies (OSA) against pituitary gland, gonads (testis, ovary) adrenal cortex, thyroid (thyroglobulin and microsomal), pancreas islet cells, gastric parietal cells and intestinal epithelial cells were evaluated in 45 patients with hypopituitarism (mean age 12.4 +/- 4.0 years). In 22 of them, 9 with isolated growth hormone (GH) deficiency (IGHD) and 13 with multiple pituitary hormone deficiency, MRI showed anterior pituitary hypoplasia with structural stalk abnormality and ectopic posterior pituitary. Twelve had isolated small anterior pituitary and IGHD and 11 had normal morphology of pituitary gland and IGHD. Controls were healthy age-sex-matched subjects. Thyroid antibodies were detected by a passive haemagglutination test while indirect immunofluorescence was used for the others. The auto-antibodies were found in 7/45 asymptomatic patients, a frequency not significantly different from that in controls; 5 were type NOSA and 2 type OSA. Pituitary antibodies were positive in 1 girl with IGHD and normal pituitary morphology. One girl developed hyperthyroidism during the follow up. Autoantibodies were equally distributed between the three groups and the frequency was not dissimilar from that in controls; this suggests that these patients are not at a higher risk of developing auto-immune disease, at least during the first two decades.

CONCLUSION

Pituitary insufficiency in children with different MRI features seems unlikely to be secondary to an auto-immune process.

Anticardiolipin antibodies in children and adolescents with insulin-dependent diabetes mellitus

Anticardiolipin antibodies were determined in 29 diabetic children and adolescents, aged 3.9-26.8 years, with disease duration from 1 month to 19 years. Anti-islet cell antibodies (ICA-IgG and CF-ICA), anti-insulin antibodies (IAA), antithyroid antibodies and non organ-specific (NOSA) antibodies were also determined. Patients were grouped according to insulin-dependent diabetes mellitus (IDDM) duration: group I (n = 11) < 6 months, and group II (n = 18) > 5 years. Eleven of group II patients showed precocious signs of micro-angiopathic complications. Forty-two age- and sex-matched healthy subjects served as controls. IgG and IgM anticardiolipin antibodies were evaluated by ELISA and their results expressed as arbitrary units (AU). IgG anticardiolipin antibodies were found in 7 patients (24%), while IgM anticardiolipin antibodies were absent in all. IgG anticardiolipin antibodies were more frequent in IDDM patients than in controls (P < 0.005) and group I (in 6 out of 11 patients; 54.5%) than in group II (in 1 out of 18 patients; 5.5%) (P < 0.025). In five out of six group I patients with IgG anticardiolipin antibodies, ICA-IgG and/or CF-ICA were also found. No correlation was observed between anticardiolipin and other auto-antibodies, micro-angiopathic complications, and HLA typing.

CONCLUSION

Anticardiolipin antibodies may reflect an abnormal immunological response in the early stage of diabetes mellitus and represent a transient auto-immune phenomenon.

Immunoglobulin allotypes (GM and KM) and their interactions with HLA antigens in autoimmune diseases: a review

GM and KM immunoglobulin (Ig) allotypes and their interactions with HLA antigens have been analyzed in various autoimmune diseases: multiple sclerosis, rheumatoid arthritis, insulin-dependent diabetes mellitus (IDDM), systemic lupus erythematosus, coeliac disease, Crohn's disease, Graves' disease, atrophic thyroiditis, Hashimoto's thyroiditis, myasthenia gravis, chronic active hepatitis, alopecia areata, uveitis, vitiligo, Turner's syndrome, glomerular nephritis, Berger's disease and idiopathic dilated cardiomyopathy. This review reports published results about associations or linkages, as well as the origins of the populations, the numbers of patients and controls tested. The possible role of Ig polymorphisms in the physiopathology of autoimmune diseases is discussed. Ig allotypes and statistical methods used to analyse the HLA and Ig data are also described.

HLA-A, B and DR antigens in patients with gonadal dysgenesis

HLA (human leukocyte antigens) antigens A, B, and DR were determined in a series of 50 patients with gonadal dysgenesis (GD), separated into different groups according to karyotype. There were no significant differences in frequency of HLA antigen types between GD patients and the population control. When frequencies of the HLA antigens in the various GD patient groups by karyotype were compared, only one significant difference was found: HLA-A3 was more common among GD patients with isochromosome X than among GD patients with karyotype 45,X (p < 0.001, corr. p < 0.008). Although GD patients have a higher expectancy for development of autoimmune disorders, and in our 50 patients thyroglobulin and/or microsomal antibodies were detected in 20 (i.e., 40%), we failed to find any increased frequency of specific HLA antigen types known to be associated with juvenile autoimmune thyroiditis.

Adrenocorticotrophin stimulation and HLA polymorphisms suggest a high frequency of heterozygosity for steroid 21-hydroxylase deficiency in patients with Turner's syndrome and their families

OBJECTIVE

Following the chance observation of congenital adrenal hyperplasia in a patient with Turner's syndrome we decided to evaluate the incidence of 21-hydroxylase deficiency (21-OHD) in patients with Turner's syndrome and in their relatives.

SUBJECTS

Fifty-two patients with Turner's syndrome (mean age +/- SD 14.7 +/- 5.6 years) and 26 relatives were studied.

MEASUREMENTS

17-Hydroxyprogesterone (17-OHP) serum levels before and after i.m. administration of 0.25 mg of ACTH(1-24) were evaluated in patients with Turner's syndrome and relatives. In Turner patients basal testosterone and dehydroepiandrosterone concentrations were determined. The results of ACTH tests were analysed according to HLA class I and II alleles of subjects.

RESULTS

The baseline 17-OHP was in the range of the classical form of 21-OHD in one Turner patient, who had severe clitoral enlargement since birth. In 11 patients the stimulated 17-OHP serum level was higher than in normal controls and similar to that found in 21-OHD heterozygous subjects. Clitoral enlargement was significantly more frequent in patients with high stimulated 17-OHP levels (P < 0.001). The frequency of heterozygous-type responses was higher in Turner subjects (1:4.6) than in the Italian population (1:47 for the classic form and 1:9.5 for the non-classic form of the disease). In our patients the frequencies of HLA antigens and haplotypes, usually associated with 21-OHD, were different compared to the controls. HLA-B8, which is negatively associated to 21-OHD, was less frequent in Turner patients than in controls and absent in those with an elevated 17-OHP level. HLA-B14, B22 and B35 were more frequent, though not significantly so, in Turner patients than in controls and even more so in the group with an elevated 17-OHP level. The same investigations performed in 26 relatives of the Turner patients showed a high frequency of carriers of 21-OHD and three subjects with the cryptic form of the disease.

CONCLUSIONS

Although in the literature there are only two reports of the association of Turner's syndrome and 21-OHD, on the basis of our experience this association was more frequent, in the Italian population. Since some of the typical signs of 21-OHD (short final stature, varying degrees of virilization, menstrual irregularities, amenorrhoea, infertility) in patients with Turner's syndrome could also be attributed to the chromosomal abnormality, it is therefore more difficult to diagnose 21-OHD in Turner subjects. Adrenal function should be assessed, at least in the presence of clitoral enlargement, in patients with Turner's syndrome, particularly if their karyotype does not contain a Y chromosome. The hypothesis of the presence of cryptic Y chromosome material in these patients should also be considered.

CD5-positive B cells in type 1 (insulin-dependent) diabetic children

We have measured CD5+ B cell levels in the peripheral blood of 35 type 1 (insulin-dependent) diabetic children, aged 1.1-21.2 years (10.7 +/- 4.6 years). Patients were divided into two groups according to disease duration (group I < 6 months and group II > 1.5 years). Group I included 18 patients and group II 17 patients. Thirty-nine healthy subjects, comparable for age and sex, served as controls. CD5+ B cells were identified by double immunofluorescence staining with rhodamine-conjugated rabbit anti-human immunoglobulin and with a mouse anti-CD5 monoclonal antibody revealed by a fluorescein-conjugated goat anti-mouse immunoglobulin. We found that CD5+ B cell levels (expressed as percentages of peripheral blood B lymphocytes) were significantly higher in group I (median 24; range 4-48) than in controls (median 14; range 0-36, P < 0.001) and in group II (median 4; range 0-20, P < 0.001). A follow-up study of 12 group I patients showed a significant decline in CD5+ B cell levels. The data obtained in our diabetic patients suggest that CD5+ B cells are expanded in the early phase of type 1 diabetes mellitus and may play a role in the autoimmune process of the disease.

Transient IgG subclass deficiencies in newly diagnosed diabetic children

In 27 children (15 males and 12 females) with insulin-dependent diabetes mellitus (IDDM), aged 1.2-13.5 years (mean 9.9 +/- 3.6 years) we investigated immunoglobulins (IgG, IgA, IgM), IgG subclass levels and islet-cell antibodies (ICA) at diagnosis and at 6 and 12 months after disease onset. At diagnosis, IgG levels were lower than -2SD in 7 patients (26%), IgA in 1 (3.7%), IgM in 1 (3.7%). IgG subclass levels were below the 3rd percentile in 13 patients (48.1%); in particular IgG1 in 7 (26%), IgG2 in 3 (11.1%), IgG3 in 2 and IgG4 undetectable in 1 case. In 3 out of the 13 patients combined IgG1-IgG3, IgG1-IgG2 and IgG1-IgG4-IgA deficiencies were observed. ICA were greater than 20 Juvenile Diabetes Foundation units in 17/27 patients. The HLA-DR2 frequency was higher in patients with IgG subclass deficiency than in patients with normal IgG subclass levels. During follow up, IgG levels normalized in 6 patients while IgA and IgM did not change. IgG1 normalized in 5 out of the 7 patients, IgG2 in all patients while IgG3 and IgG4 did not change. One year later ICA were still present in 8/27 patients. The hypogammaglobulinaemia and IgG subclass deficiencies observed in our patients could have either a genetic or an acquired basis.

Influence of HLA genotype on birth weight of patients with Turner syndrome

Growth failure starting before birth is a common characteristic in Turner syndrome, and its pathogenesis is still not completely explained. Experiments performed in mice and rats to test whether a genetic disparity between mothers and offspring and maternal immunological status have any influence on litter size have demonstrated that allogenic litters are significantly larger in size than genetically compatible ones. Studies in humans have given contrasting results, but some authors have found that heterozygosity at enzyme loci and in blood groups is positively correlated with intrauterine growth. HLA class I and II polymorphisms were defined in 53 patients with Turner syndrome and in their parents, and lymphocytotoxic antibody detection was performed in 36 mothers. These data were related to the patients' birth weight. The frequency of the HLA-B16 allele in patients with a birth weight greater than 10th centile was significantly higher in comparison with those less than 10th centile. HLA antigen sharing was present in 43 couples (81.1%). Mean birth weight was 2934 +/- 472 g in patients without HLA antigen parental sharing and 2721 +/- 529 g in those whose parents shared HLA antigens. The mean birth weight of the 10 patients whose parents do not share HLA antigens was significantly higher than that of the patients with parental HLA-B+ DR sharing (P less than 0.05) and not significantly highe than in those patients with parental HLA sharing at other HLA loci. Patients whose parents shared B+DR antigens also had significantly smaller birth weights than those with B and A+B+DR sharing (P less than 0.025 and P less than 0.025). No significant difference in mean birth weight was found in relation to other parameters, such as mother-child histocompatibility, HLA homozygosity and lymphocytotoxic production in the mothers.

Autoimmunity in vitiligo: relationship with HLA, Gm and Km polymorphisms

Eighty-six patients affected by vitiligo were investigated for Gm, and Km polymorphisms, HLA markers and the presence of organ and non organ-specific autoantibodies. Vitiligo patients had an increased frequency of autoantibodies (71%), in particular anti-parietal cells (26.6%), antithyroglobulin (24.4%) and antithyroid microsomal antibodies (43%). One patient was also affected by Hashimoto's thyroiditis, 4 by Graves' disease and two others by nontoxic, multinodular goiter. No correlation was found between chronologic age and sex and the presence of autoantibodies, while an increased frequency of organ-specific autoantibodies was found with longer duration of vitiligo. HLA-A3 and Gm (3; 23; 5, 10, 11, 13, 14) phenotype frequencies were significantly increased in patients without autoantibodies (P less than 0.05). Patients negative for these two phenotypes were significantly more prone to develop autoantibodies than those positive (P = 0.0032). C4AQO allele showed a significantly decreased frequency in the whole group of patients when compared to the controls (P less than 0.05).

Excess of HLA parental sharing in families with Turner patients

In utero selection processes are probably related to mother-father compatibility as has been reported in abortion-prone couples and in Down syndrome studies. In order to analyse this phenomenon, we investigated families with chromosomal imbalance (Turner syndrome). We chose this model because previous data indicated a high frequency of HLA-A31 and B38 in Turner patients and in their mothers. We report high HLA antigen sharing in Turner families and great histocompatibility between mother and affected daughter, not related to abortion histories. The proportion of HLA-A homozygous cases among Turner children was higher than expected. The level of lymphocytotoxic antibodies against fetus in mothers of Turner patients was comparable to that of mothers of families with normal fertility and probably favoured these pregnancies.