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Recent cloning of RH genes has elucidated their structure, suggesting that RH proteins are part of an oligomeric complex with transport function in the erythrocyte. This observation prompted us to investigate a possible relationship between the RH system and the glycosylated hemoglobin level (Hb A(1c)) in diabetes. This compound is considered an important indicator- of glycemic control in diabetic disorders. We studied 278 subjects with non-insulin-dependent diabetes mellitus (NIDDM) from the population of Penne, Italy. Glycemic and glycosylated hemoglobin (Hb A(1c)) levels are associated with RH phenotype. Glucose and Hb A(1c) levels are increased in DCcEe subjects and decreased in ddccee subjects as compared to the mean values for other genotypes. Sex, age at onset of disease, duration of disease, and age of patients were also considered. Correlation analysis suggests that these variables influence glycemia directly and Hb A(1c) indirectly. The RH system, on the other hand, seems to influence the Hb A(1c) level directly. Preliminary data on 53 children with insulin-dependent diabetes mellitus (IDDM) from Sardinia seem to confirm the relationship between RH and Hb A(1c) observed in NIDDM. Since glycosylated hemoglobin is found inside red blood cells, the relationship between RH genetic variability and Hb A(1c) level suggests that RH proteins may influence glucose transport through red cell membrane and/or hemoglobin glycation.

Objective: To determine whether polymorphism in the manganese superoxide dismutase (MnSOD) gene is associated with susceptibility or disease outcome in rheumatoid arthritis (RA)., Methods: We used a case-control approach with 153 RA patients and 218 control subjects to examine for any associations between MnSOD genotypes and susceptibility to RA. We also investigated the influence of genotypes on radiologic outcome, as measured using the Larsen score for radiographs of the hands and feet, and on functional outcome, as assessed by the Health Assessment Questionnaire. MnSOD typing was carried out using polymerase chain reaction-based methods. Results were analyzed using multiple regression analysis, with adjustment for age, sex, and disease duration. In separate analyses, we corrected for rheumatoid factor (RF) status and/or the presence of the HLA-DRB1 "shared epitope" (SE). We also examined whether radiologic outcome was influenced by interactions between MnSOD and glutathione S-transferase (GST) genes., Results: No association between MnSOD genotype and development of RA was found. The MnSOD VV genotype was associated with a significantly higher (P = 0.04) Larsen score (104.4) than MnSOD AA (83.0), while MnSOD AV was associated with an intermediate score (91.8). Correction for RF status had no significant effect on the results of the analysis, but significance was lost (P = 0.09) after correction for the presence of the SE. There was evidence of interaction between the GSTT1 and MnSOD genotypes, with the MnSOD VV/GSTT1-null combination being associated with the highest Larsen score (142.1; P = 0.007 after correction for the SE)., Conclusion: Polymorphism in the MnSOD gene is not associated with susceptibility to RA. Our data suggest that MnSOD VV is associated with more severe radiologic outcome, although this relationship may not be independent of the effect of the SE. However, interaction between MnSOD and GST genes appears to influence radiologic outcome independently of the SE.

A total of 154 individuals belonging to three populations located at different altitude levels in northwest Argentina (San Salvador de Jujuy, 1,200 m; Tilcara, 2,500 m; Abra Pampa, 3,500 m) were studied for the GM, KM, HP, GC, PI and TF genetic systems. Individuals were selected on the basis of ethnocultural affiliation. Gene frequency values were found to be comparable to those reported for other South American populations. The populations studied showed a close genetic identity and an absence of interpopulation heterogeneity. Distribution of the GM phenotypes and haplotypes corresponds to historical data on human settlements in Jujuy Province. The presence of some alleles and the anthropological significance of the allele distribution are discussed, as are the effects of the admixture with Africans and Spaniards. The genetic pattern appears to be the result of a varying admixture due to the genetic isolation in populations located at various altitude levels.

Objective: Sarcoidosis is believed to be one of the T cell-mediated granulomatous diseases with unknown aetiology. We attempt to search for the causative T cell clones of sarcoidosis., Methods: We study T cell receptor beta-chain variable region (Vbeta) repertoire in peripheral blood (PB) and bronchoalveolar lavage fluid (BALF) from patients with sarcoidosis, using semi-quantitative reverse transcriptase-polymerase chain reaction method. The expression of 22 kinds of Vbeta genes is examined in 17 patients with sarcoidosis and nine normal subjects., Results: Compared with control subjects, the group with sarcoidosis exhibits significantly high expressions of the Vbeta2 (P < 0.005, Wilcoxon's test) and Vbeta6 (P = 0.005) genes in BALF. In each BALF sample, the Vbeta2 (P < 0.01, chi2 test) and Vbeta6 (P < 0.01) genes were overexpressed (> 2 SD above the mean value for each Vbeta observed in control subjects) in 11 and 10 of 17 patients with sarcoidosis, respectively. Furthermore, the amino acid sequences of Vbeta6+ complementarity determining region 3 were conserved in one of three patients. There is, however, no disposition of Vbeta gene usage in PB from patients with sarcoidosis compared with control subjects., Conclusions: The T lymphocytes with Vbeta2 and/or Vbeta6 are associated with the pathogenesis of sarcoidosis. The possibility exists that these T lymphocytes might be capable of recognizing the restricted antigens, thereby inducing oligoclonal expansion.

One of the obstacles to progress in dairy cattle selection is that milk production traits are only expressed after the first calving. However, the use of the quantitative trait loci (QTL) technology will improve the efficiency of dairy industry with a positive image for the consumers. QTL are part of the genome showing a preponderant action and explaining the major part of variation of the trait production. At the present time, the two major strategies developed to detect such QTL are the candidate gene approach and the positional genetics approach. The somatotropic axis contains the most promising candidates in this respect, as it strongly regulates milk production. Then, the identification of favorable QTL associated with the somatotropic axis that are significantly correlated with genetic merits for milk production could lead to more effective selection programs.

Neuroendocrine tumours of the gastroenteropancreatic tract are growths originating either from the cells of the diffuse (neuro)endocrine system, such as gastric carcinoids and islet cell tumours, or from nerve structures, such as duodenal paragangliomas. A great deal of cellular and clinical information is available whereas data concerning the genetic and molecular basis of diffuse (neuro)endocrine system tumours of the gastroenteropancreatic tract are very few and fragmentary. The present paper reviews some genetic and molecular investigations of potential interest. As far as concerns the genetic background of diffuse (neuro)endocrine system tumours, the frequent loss of heterozygosity for the locus of Multiple Endocrine Neoplasia type 1 in tumour samples suggests a potential role of the Multiple Endocrine Neoplasia gene. With regard to the molecular background, no mutation of the p53 or retinoblastoma susceptibility (Rb) genes has been demonstrated. Useful data have been generated by in situ analysis of the proliferation activity of tumours.

Several studies have suggested a role for the histocompatibility complex of loci (HLA) in the genetic susceptibility to autism. We have tested this hypothesis by linkage analysis using genetic marker loci in the HLA region on chromosome 6p in multiplex families with autism. We have examined sharing of alleles identical by descent in 97 affected sib pairs from 90 families. Results demonstrate no deviation from the null expectation of 50% sharing of alleles in this region; in fact, for most marker loci, the observed sharing was less than 50%. Thus, it is unlikely that loci in this region contribute to the genetic etiology of autism to any significant extent in our families.

In this study, a PstI polymorphic site with two individual alleles, namely A1 and A2, was identified withinthe boundary between intron 1 and exon 2 of the cholecystokinin (CCK) type A receptor gene. The PstI polymorphic site was used as a genetic marker to study its association with psychotic symptoms in schizophrenia. A significant difference in allelic frequency was found between schizophrenic patients with and without auditory hallucinations(chi(2) = 6.26, df = 1, P = 0.012), and the odds ratio for the allelic association was 2.21 (95% CI 1.18-4.15) with an attributable fraction of 0.1. The frequency of A1-A1 and A1-A2 genotypes showed a significant excess in schizophrenic patients with auditory hallucinations as compared to those without such symptoms (chi(2) = 5.45, df = 1, P = 0.02), and the odds ratio for the genotypic association was 2.27 (95% CI 1. 13-4.57) with an attributable fraction of 0.177. The haplotype-based haplotype relative risk (HHRR) test revealed a significant difference between transmitted and non-transmitted alleles in nuclear families of schizophrenic patients with auditory hallucinations (chi(2) = 4.54, df = 1,P = 0.033) but not in those of schizophrenic patients without them. The present study suggests that the CCK-A receptor gene may be associated with auditory hallucinations in schizophrenia.

Pooling DNA from subjects within a group and comparing the pooled DNA across groups for a dense map of DNA markers offers a solution to the conundrum that linkage is systematic but not powerful whereas allelic association is powerful but not systematic. We used DNA pooling to screen 66 markers on chromosome 22 in original and replication samples of children of high general cognitive ability (g) and controls of average g. Although none of these markers survived our three-stage screening design (original pooling, replication pooling, individual genotyping), the results of DNA pooling were largely confirmed by individual genotyping. We can therefore exclude associations of major effect size on chromosome 22 for g, a key variable for cognitive neuroscience research on learning and memory.

Atrial natriuretic peptide (ANP), B-type natriuretic peptide (BNP) and C-type natriuretic peptide are the known members of the mammalian natriuretic peptide system. ANP and BNP genes are expressed in a specific manner in cardiac myocytes. They are natriuretic and diuretic hormones and cause vasorelaxation. ANP is mainly synthesized in the atria of the normal adult heart. However, ventricular hypertrophy is characterized by an augmentation of the synthesis and release of ANP from the ventricles. BNP is expressed in both the atria and the ventricles, but is mainly released from the ventricles. The major determinant of ANP and BNP secretion is wall stretch, and the levels of BNP messenger RNA increase substantially in response to cardiac overload. Acute increase in BNP gene expression occurs within 1 h and mimics the rapid induction of proto-oncogenes in response to haemodynamic stress. BNP can be used as a myocyte-specific marker to identify mechanisms that couple acute mechanical overload to alterations in cardiac gene expression.

Balkan endemic nephropathy (BEN) is of great clinical importance in the restricted areas of Bulgaria, Rumania, Croatia, Serbia, Bosnia and Herzegovina. So far, studies on the etiological factors for BEN have not discovered any single environmental causative agent of this puzzling disease. These data reject the possibility of a purely environmental causation of BEN. The pattern of BEN transmission in the risk families is not typical for single gene disorders. Extensive epidemiological and genetic studies disclose characteristics of multifactorial (polygenic) inheritance of BEN. The evidences of 'familial tendency', variation of the risk for BEN depending on the number of sick parents and the degree of relatedness; the development of BEN in individuals from at-risk families who were born in non-endemic areas; the data that disease is not found in the gypsy population and the expressions of 3q25 cytogenetic marker suggest that the genetic factors play an important role as causative factors in BEN development. The possible impact of environmental triggers on individuals genetically predisposed to BEN could be supposed by the following data: the cytogenetic results of the increased frequency of folate sensitive Fra sites, spontaneous or radiation-induced aberrations in several bands in BEN patients, the data from the detailed analysis of breaks in BEN patients and controls that generate structural chromosome aberrations; the occurrence of BEN in immigrants. Genetical epidemiological approaches to etiology and prevention of BEN are proposed. The predisposing genes for BEN could be genes localized in a region between 3q25-3q26; transforming growth factor-beta (TGF-beta), genetic heterogeneity of xenobiotic-metabolizing enzymes; defects in the host's immune system. The predisposing genes for BEN patients with urinary tract tumors could be germline mutations in tumor suppressor genes and acquired somatic mutations in oncogenes.

The major histocompatibility complex (MHC) is a multi-gene family unique to the vertebrates, whose products function to present peptides to T cells. Certain MHC loci are highly polymorphic, and this polymorphism is maintained by a form of balancing selection, probably overdominant selection. This selection has several consequences for MHC biology that make these genes different from neutrally evolving genes: an enhanced rate of nonsynonymous nucleotide substitution in codons encoding the peptide-binding region; long-lasting ("trans-species") polymorphism; and homogenization of introns relative to exons as a result of recombination and subsequent genetic drift. The MHC also reveals evidence of processes shared with other multi-gene families, including gene duplication and deletion and a low level of inter-locus recombination.

Myostatin belongs to the transforming growth factor-beta superfamily, and is expressed specifically in developing and mature skeletal muscle. Myostatin appears to act as a negative regulator of muscle development, since mice with targeted disruption of this gene display a large increase in muscle mass. In this study, the porcine myostatin gene was mapped to chromosome 15q2.3 by fluorescence in situ hybridization. Myostatin was also positioned within the chromosome 15 linkage group using both a polymorphism located in the second intron and an associated microsatellite. The development of highly polymorphic markers associated with myostatin will support population studies to identify alleles of this gene that affects muscle mass and/or fat deposition in swine.

A set of yeast strains based on Saccharomyces cerevisiae S288C in which commonly used selectable marker genes are deleted by design based on the yeast genome sequence has been constructed and analysed. These strains minimize or eliminate the homology to the corresponding marker genes in commonly used vectors without significantly affecting adjacent gene expression. Because the homology between commonly used auxotrophic marker gene segments and genomic sequences has been largely or completely abolished, these strains will also reduce plasmid integration events which can interfere with a wide variety of molecular genetic applications. We also report the construction of new members of the pRS400 series of vectors, containing the kanMX, ADE2 and MET15 genes.

By investigating a group of 39 unrelated adults suffering from vitiligo it was found that alleles HLA-DRB1*0701, -DQB1*0201, and -DPB1*1601 differed in their frequencies in comparison to those observed in the healthy population. The allele HLA-DRB1*0701 was found in 26.5% of patients compared to 14.2% in the healthy group (p < 0,01, RR = 2.17). The allele HLA-DQB1*0201 was present in 33.8% of patients compared to 21.2% (p < 0,025, RR = 1.89). The allele HLA-DPB1*1601 was found in 6.41% of patients compared to 2.05% in the healthy group (p < 0.05, RR = 3.3). No other significant deviations in the frequencies of investigated alleles were observed.

Radiation hybrid mapping has become an established tool for building physical maps. It represents a powerful way of constructing YAC contigs and high-resolution maps for positional cloning experiments. Ideally, radiation hybrids should not only provide support for the true order of the markers, but also accurate estimates of the physical distances between them. Statistical analysis of radiation hybrids has proved difficult because of the number of parameters (representing the fragment retention probabilities) that must be estimated, and simplifying assumptions are needed to analyze large numbers of markers simultaneously. The ramifications of these assumptions for the calculation of physical distances are investigated. A simple two-locus model is presented to demonstrate that variation in marker retention can lead to distortions in the estimates of distance. Multilocus simulations show that, when marker retention is constant across the chromosome, good estimates of physical distance can be derived using simple models of retention. However, further simulations exploring variable retention schemes demonstrate that significant errors in the estimates of map distances can occur. Ways of minimizing these distortions are discussed.

Co-expression of several members of the matrix metalloproteinase (MMP) family is a characteristic of human carcinomas. To investigate the role of the recently cloned collagenase-3 (MMP-13) in epidermal tumors, we studied samples representing malignant (basal and squamous cell carcinoma, Paget's disease), pre-malignant (Bowen's disease, solar keratosis), and benign (keratoacanthoma, seborrheic keratosis, linear epidermal nevus) tumors. Basal cell carcinomas expressed collagenase-3 mRNA in focal areas of keratinized cells, the squamous differentiation of which was confirmed by positive immunostaining for involucrin. Apoptosis was observed in central parts of these foci. In squamous cell carcinomas, collagenase-3 expression was detected at the epithelial tumor front and less frequently in the surrounding stromal cells. Collagenase-3 mRNA co-localized with immunostaining for laminin-5, an adhesion molecule suggested to participate in the migration of tumor cells. The pre-malignant and benign tumors were mostly negative for collagenase-3. Stromelysin-1, a potential activator of latent collagenases, was frequently expressed by stromal cells surrounding the malignant tumors, and the two MMPs occasionally co-localized in keratotic foci. Our results demonstrate that in basal cell carcinomas, expression of collagenase-3 is associated with terminal differentiation of epithelial cells. Furthermore, the gene is activated during skin carcinogenesis, and we suggest a role for collagenase-3 in degradation of the extracellular matrix associated with malignant epithelial growth.

Serum pepsinogen, alpha 1-antitrypsin (alpha 1-AT) and blood groups were studied as genetic markers in 32 patients with endoscopically proven duodenal ulcer and 44 control subjects with no family history of ulcer disease. Serum pepsinogen was determined by the modified method of Edward et al, alpha 1-AT by single radial immunodiffusion (RID) and phenotyping was carried out by isoelectric focusing (IEF). Duodenal ulcer patients with hyper- pepsinogenemia (28%) and low serum alpha 1-AT (35%) had a dominant blood group O, lower mean age, an early onset of disease, a higher frequency of gastrointestinal (GI) bleeding and ulcer perforation. These parameters were found considerably different in patients with normal serum pepsinogen and alpha 1-AT. Phenotype analysis of alpha 1-AT revealed that four duodenal ulcer patients had partial deficiency of the protease inhibitor and none of the normal exhibited the deficiency pattern. The etiology of the disease appears to be genetic anomaly in 28% of patients while the rest (72%) had ulcers as a result of neuroendocrinological or environmental factors.

Both population (mass) strategies and targeted strategies for the management of high blood pressure are necessary. However, it has yet to be proven that reducing blood pressure by lifestyle changes in the population will confer the same cardiovascular benefit that results from lowering blood pressure by drugs. It is important to identify and correct those factors in hypertensive patients, such as obesity, smoking, elevated lipids, and diabetes, that confer high risk for an adverse cardiovascular event. It is now recognized that cardiovascular risk involves not only diet and lifestyle effects but that the structural and functional abnormalities resulting from high blood pressure are of great importance. There is a need to develop and validate new noninvasive methods for quantitating these structural and functional changes, together with assessment of endothelial dysfunction, hormonal profiling, and identification of susceptible genes so that high risk patients with hypertension can be selected for drug therapy. In the future, selection of an appropriate antihypertensive drug for an individual patient should also involve consideration of risk factors, structural changes, hormonal status, and genetic consideration. Central inhibition of peripheral sympathetic action by imidazoline receptor agonists, such as moxonidine, may lead to reversal of these structural and functional abnormalities without adverse effects on the central nervous system.

An extremely low production rate of a polymorphic allele (formally called the mutation rate)--a prerequisite for using the allele as a marker (particularly for anthropogenetic purposes where the alleles must be assumed to be monophyletic)--cannot be taken for granted for alleles of highly polymorphic VNTRs, but a low production rate can be used to identify alleles produced by a single nucleotide substitution. This property was indirectly tested for the (ACT)n COL1A2 (of type I collagen) microsatellite SSTR (degree of heterozygosity H = 0.72) by searching for linkage disequilibria between the SSTR's four common alleles (n = 6, 8, 9, or 10) and three RFLPs of the same gene. A strong linkage disequilibrium between at least three of the four SSTR alleles and two of the three closely linked RFLPs has been demonstrated in a Sardinian population (Italy), a finding that suggests a low production rate of these alleles. Thus it seems that this highly polymorphic system and, by a reasonable extrapolation, other VNTRs with a comparable degree of heterozygosity may be valuable anthropogenetic markers, at least in distinguishing subgroups of a major ethnic group.

Genetic diversity among ethnic groups is studied by comparing the genetic fingerprint of the examined groups. This index is constructed by aggregating the differential frequencies of various marker characteristics. Recent advances in the study of human biological rhythms may provide new indexes that will complement the genetic profile of a population. One of the rhythm parameters that is especially useful for this purpose is the acrophase (peak time location). The aim of the present study is to construct a rhythm profile based on acrophase distribution for various human groups and to estimate the contribution of genetic and environmental factors to that profile. The rhythm profiles were constructed by comparing the acrophases of 11 plasma hormones in women from three different ethnic-geographic populations (North Americans, Romanians, and Japanese) with reference to three age groups (adolescence-early postpuberty, young adulthood, and postmenopause). Genetic distances of these ethnic groups were determined by 14 genetic markers. Cluster and principal coordinates analyses were used to define the variation of the two parameters (genetic distances and acrophase dispersion). The analyses show that North Americans and Romanians are closer to each other with regard to both parameters and far apart from the Japanese. However, there was a difference between the variation presented by the first eigenvalue of the genetic profiles (94.5%) and that of the first eigenvalue of the acrophase pattern (69.1%), which means reduction in the variability (increased similarity) among the three ethnic groups according to the acrophase profiles.(ABSTRACT TRUNCATED AT 250 WORDS)

Contemporary problems have been presented, related to pathogenesis, clinical pathology and epidemiology of leprosy. It has been stressed that intensity of cell mediated immune response in the patient determines not only resistance or susceptibility to infection with Mycobacterium leprae but also defines traits of clinical pathology in leprosy, thus providing the basis for modern clinical classification. Present aims and investigative methods in lepra epidemiology have been shown. Current data have been provided on spread of leprosy in various parts of the world, mainly those remaining under monitoring by the World Health Organization. The data point to significant decrease in registered leprosy cases in the regions beginning from 1986 and, in particular, in years 1990-1994. The decrease has resulted from adequate verification of the disease stage in the patients and from applying the recommended multidrug therapy. The needs and perspectives of actions aiming at combatting leprosy have been described, aiming at eradication of leprosy as the international health problem till the year 2000. It has been stressed that at present, leprosy is no longer a hopeless disease and that it can be cured when sufficiently early diagnosed and properly treated.

To determine the HLA-linked immune response gene that controls low responsiveness to hepatitis B surface antigen (HBsAg), HLA typing was performed in 33 initial non-responders (male:female = 23:10, age 1.5-46 years) who had poor antibody response (anti-HBs < 10 mIU ml-1) after four doses of plasma-derived hepatitis B vaccine. Of 33 initial non-responders, 26 received two additional doses of either the same vaccine (n = 18) or recombinant hepatitis B vaccine (n = 8) and returned for anti-HBs measurement. At 1 month after the sixth dose, anti-HBs was still < 10 mIU ml-1 in 20 cases and 10-20 mIU ml-1 in three cases. Analysis of HLA antigen frequencies in these 23 ultimate low responders revealed that nine (39%) were positive for DR14, a statistically significant association of low responsiveness to hepatitis B vaccine with HLA-DR14. In addition, 26% of the ultimate low-responders were positive for DQ3, a frequency significantly lower than the expected rate in the general population. Among the nine ultimate low-responders with DR14, seven were heterozygous for this allele, while the other two cases had a single isolated DR14; and all nine were in association with DR52. These results suggest that a DR14-DR52 association, probably dominantly expressed, may be involved in the low immune responsiveness to hepatitis B vaccine of the Chinese population in Taiwan.

Most strains of Helicobacter pylori are naturally competent for uptake of chromosomal DNA. Transformation frequencies for streptomycin resistance or rifampicin resistance markers ranged from 1 x 10(-4) to 1 x 10(-3) per viable cell using a plate transformation procedure. Transformation of a metronidazole resistance marker (MtrR) was demonstrated when either a laboratory-derived mutant or a MtrR clinical isolate were used as the source of donor DNA. MtrR was transformed at a frequency of 3 x 10(-5) per viable cell. All H. pylori strains tested produce large amounts of DNAase, which may reduce DNA available for transformation. Four H. pylori plasmids were isolated. DNA fragments from H. pylori plasmids were deleted or rearranged when cloned in pUC19 and propagated in Escherichia coli DH5 alpha. An H. pylori plasmid, pUOA26 which contained a chloramphenicol resistance determinant from Campylobacter coli, was constructed in H. pylori. This plasmid could be successfully introduced by natural transformation only into H. pylori recipients which contained a homologous resident plasmid. Transformation of pUOA26 into plasmid-free cells of H. pylori was achieved by electroporation. Transformation frequencies were 1 x 10(-4) transformants per viable cell when plasmid DNA was isolated from the same strain; however, introduction of pUOA26 DNA derived from H. pylori 8091 into a different H. pylori strain, NCTC 11639, resulted in transformation at much lower frequencies (< or = 1 x 10(-7) per viable cell).(ABSTRACT TRUNCATED AT 250 WORDS)

A foreign gene coding the bacterial enzyme, chloramphenicol acetyltransferase (CAT), was introduced into a primary culture of the mouse cerebellar primordium by a retrovirus vector which harbors the neomycin-resistant gene. Following selection of the gene-transferred cells based on neomycin resistance, most of the selected cells expressed the CAT gene product as well as a marker for astrocytes, glial fibrillary acidic protein (GFAP), when examined immunocytochemically. These cells were transplanted into the adult mouse cerebellum, and the surviving cells were examined immunohistochemically by marking them with anti-CAT antibody. The distribution of CAT-immunopositive cells coincided with that of GFAP-immunopositive cells observed in serial sections of grafted sites at 10 days after transplantation. Some of the transplanted CAT-immunopositive cells extended processes and exhibited the morphological appearance of fibrous astrocytes. Migration of the genetically labeled cells into the host molecular layer was also observed and the morphological plasticity of the differentiated primary cells was shown according to the grafted sites. These results indicate that stable marking of cells for grafting can be accomplished by retrovirus-mediated introduction of a foreign gene into the primary culture, and that the fate and behavior of the labeled donor cells can be analyzed immunohistochemically following transplantation into neural tissue.

We have used a probe derived from TRP-2/DT to detect migratory melanoblasts shortly after they emerge from the neural crest, as early as 10 days post coitum (dpc). TRP-2/DT expression is otherwise restricted to the presumptive pigmented retinal epithelium, the developing telencephalon and the endolymphatic duct. The pattern of steel and c-kit hybridisation in the developing brain differed from that of TRP-2. TRP-1 and tyrosinase probes also detected melanoblasts but were both expressed later in development than TRP-2. We used the TRP-2/DT probe to investigate the way that the Steel-dickie (Sld) mutation interferes with melanocyte development, and found that the membrane-bound steel growth factor which is missing in Sld/Sld mutants is necessary for the survival of melanoblasts but not for their early migration and initial differentiation.

A rapidly increasing abundance of genetic markers which can be characterized on a large scale makes an application of the genetic linkage strategy, so successful with Mendelian diseases, ever more attractive for genetic investigations of common diseases such as essential hypertension. Variability in expression, lack of phenotypic specificity and multiple causation create unique challenges when approaches originally designed for single gene inheritance are applied to disorders with complex determination.

1. In no ethnic group is the overall association between systemic sclerosis and the MHC strong enough for direct clinical use. MHC associations do support the classification of the disease into limited cutaneous systemic sclerosis and diffuse cutaneous systemic sclerosis. 2. Indications are that associations between specific subsets of patients with systemic sclerosis and genetic markers will assume greater importance both diagnostically and prognostically. The group with lung fibrosis look prime candidates, for example. 3. Genetic markers are useful means of relating chemically induced systemic sclerosis like disorders with the classical disease. Vinyl chloride disease provides an example. 4. Evidence is emerging of strong associations between certain genetic markers and autoantibody production; a similar story has emerged in systemic lupus erythematosus. We believe that, eventually, genetic tests will be used to influence treatment in at least a subset of patients with systemic sclerosis but that a dramatic breakthrough will not be made until we know how the genetics of the disease relate to the primary biochemical disease characteristic--that is, the overproduction of collagen. In this respect it has been suggested that the 5' flanking DNA of dermal collagen genes is particularly susceptible to the action of Scl-70 (topoisomerase I). A problem is how to tie this and the other observations discussed above together. The association of autoantibodies with topoisomerase I provides a tentative link between the MHC and collagen gene expression. Although the role and reason for anti-Scl-70 in systemic sclerosis is unknown, humoral autoimmunity, at least in systemic lupus erythematosus, seems to be strongly dependent on specific HLA genes. With an understanding of the function of MHC products at the molecular level, HLA and disease associations can now be analysed on a mechanistic level. For insulin dependent diabetes mellitus it has been shown that the MHC determined susceptibility to the disease is conferred by neutral residues (Val, Ser, Ala), at position 57 of the DQ beta chain, while Asp at this position correlates with resistance. A similar phenomenon has been described in rheumatoid arthritis. Although DR4 in general is associated with rheumatoid arthritis, it is heterogeneous, but a subtype of DR4 which is characterised by positively charged residues at positions 70 and 71 of the beta chains is not found in patients with rheumatoid arthritis (Wordsworth B P et al, unpublished data). A similar approach applied to the study of systemic sclerosis is likely to be similarly rewarding. The precise subtyping of the class II genes and the characterisation of their associated haplotypes is therefore required for a complete understanding of the contribution of the MHC to the disease. Additional genes linked to the MHC must not be overlooked, and are relevant to associations of haplotypes with the disease. Of particular interest are the recent reports of a new class of proteins, which are determined by genes in the MHC and which are considered to play a part in the assembly of the antigen peptide/MHC molecule complex.

By means of starch gel electrophoresis, samples were analyzed from 3 populations (Batabanó, Guanímar and Isle of Youth) of Cubanichthys cubensis adult fishes, bioregulators of mosquito larvae. A study was made of six protein systems which are considered to be under the genetic regulation of 13 loci, 3 of which are polymorphic. The electrophoretic characteristics of each of them are described. By means of the genotypical frequencies of the polymorphic systems (PGI-1, PGI-2, and PGM), the 3 populations were compared with the use of the statistical G. No significant differences were found.