Deficit schizophrenia is a discrete diagnostic category defined by neuro-immune and neurocognitive features: results of supervised machine learning

Deficit schizophrenia is characterized by neurocognitive impairments and changes in the patterning of IgA/IgM responses to plasma tryptophan catabolites (TRYCATs). In the current study, supervised pattern recognition methods, including logistic regression analysis (LRA), Support Vector Machine (SVM), and Soft Independent Modeling of Class Analogy (SIMCA), were used to examine whether deficit schizophrenia is a discrete diagnostic class with respect to Consortium To Establish a Registry for Alzheimer’s disease (CERAD) and Cambridge Neuropsychological Test Automated Battery (CANTAB) tests and IgA/IgM responses to noxious (NOX) and generally more protective (PRO) TRYCATs. We recruited patients with (n?=?40) and without (n?=?40) deficit schizophrenia and healthy volunteers (n?=?40). The combined use of TRYCAT and CERAD features strongly segregates deficit from nondeficit schizophrenia and healthy controls. Three out of the top five most important features in LRA, SVM and SIMCA agreed, namely two different NOX/PRO TRYCAT ratios and false memory recall. SIMCA shows that deficit schizophrenia is significantly separated from nondeficit schizophrenia and controls with as top 6 features IgA responses to picolinic acid, IgM responses to 3-OH-kynurenine and kynurenic acid, and impairments in Word List Memory and Verbal Fluency Tests and Mini-Mental State Examination. Nevertheless, nondeficit schizophrenia was not significantly separated from controls. The results show that schizophrenia is not a unitary disease with mere continuous differences in severity of illness between apparent subtypes. Deficit schizophrenia is a qualitatively distinct class defined by neuroimmune (autoimmune responses to TRYCATs) and neurocognitive (episodic and semantic memory) features coupled or not with clinical (negative) symptoms.     

In vivo stability of heterogeneous expression classes in clinical isolates of methicillin-resistant staphylococci

To define the stability of methicillin-resistant Staphylococcus aureus (MRSA) in vivo, 22 isolates collected at one New York institution in 1989 and 1990 were studied. All 22 belonged to one of two distinct methicillin-resistant phenotypes (class 3 or 2), which were precisely identified as belonging to two distinct genotypes. Genotypic classification was based on restriction analysis of chromosomal DNA with EcoRI and HindIII and Southern analysis of ClaI digests using two DNA probes. One was specific for the mec gene; the other was specific for transposon Tn554. The findings suggest that the MRSA isolates studied were representative of two genetically distinct MRSA "clones," each with a unique strain-specific methicillin-resistant phenotype that is stable under the conditions of invasive disease, carriage, and spread from patient to patient.     

Diagnosis of basal cell carcinoma by infrared spectroscopy of whole blood samples applying soft independent modeling class analogy

Attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy was applied to discriminate the blood samples obtained from healthy people and those with basal cell carcinoma, demonstrating high accuracy while soft independent modeling class analogy (SIMCA) chemometric technique is benefited. It was aimed to classify the normal case and cancer case blood samples through the use of ATR-FTIR spectroscopy as a rapid method while the sample preparation is so easy in comparison with the common pathologic methods. A total of 72 blood samples, including 32 cancer and 40 normal cases, were analyzed in 1,800-900 cm(-1) spectral region. Results showed 97.6% of accuracy being compared with the current clinical methods. Research results were exemplified with comparable data of other classification methods such as principal component analysis (PCA) and Cluster analysis. The residual errors in prediction (REP) of calibration model for normal and cancerous groups in SIMCA method were 0.00362 and 0.00343, respectively.     

Targeted next-generation sequencing reveals MODY in up to 6.5% of antibody-negative diabetes cases listed in the Norwegian Childhood Diabetes Registry

Aims/hypothesis

MODY can be wrongly diagnosed as type 1 diabetes in children. We aimed to find the prevalence of MODY in a nationwide population-based registry of childhood diabetes.

Methods

Using next-generation sequencing, we screened the HNF1A, HNF4A, HNF1B, GCK and INS genes in all 469 children (12.1%) negative for both GAD and IA-2 autoantibodies and 469 antibody-positive matched controls selected from the Norwegian Childhood Diabetes Registry (3882 children). Variants were classified using clinical diagnostic criteria for pathogenicity ranging from class 1 (neutral) to class 5 (pathogenic).

Results

We identified 58 rare exonic and splice variants in cases and controls. Among antibody-negative patients, 6.5% had genetic variants of classes 3–5 (vs 2.4% in controls; p?=?0.002). For the stricter classification (classes 4 and 5), the corresponding number was 4.1% (vs 0.2% in controls; p?=?1.6?×?10^?5). HNF1A showed the strongest enrichment of class 3–5 variants, with 3.9% among antibody-negative patients (vs 0.4% in controls; p?=?0.0002). Antibody-negative carriers of variants in class 3 had a similar phenotype to those carrying variants in classes 4 and 5.

Conclusions/interpretation

This is the first study screening for MODY in all antibody-negative children in a nationwide population-based registry. Our results suggest that the prevalence of MODY in antibody-negative childhood diabetes may reach 6.5%. One-third of these MODY cases had not been recognised by clinicians. Since a precise diagnosis is important for treatment and genetic counselling, molecular screening of all antibody-negative children should be considered in routine diagnostics.

     

From the Cover: High-impact rare genetic variants in severe schizophrenia

Extreme phenotype sequencing has led to the identification of high-impact rare genetic variants for many complex disorders but has not been applied to studies of severe schizophrenia. We sequenced 112 individuals with severe, extremely treatment-resistant schizophrenia, 218 individuals with typical schizophrenia, and 4,929 controls. We compared the burden of rare, damaging missense and loss-of-function variants between severe, extremely treatment-resistant schizophrenia, typical schizophrenia, and controls across mutation intolerant genes. Individuals with severe, extremely treatment-resistant schizophrenia had a high burden of rare loss-of-function (odds ratio, 1.91; 95% CI, 1.39 to 2.63; P = 7.8 × 10⁻⁵) and damaging missense variants in intolerant genes (odds ratio, 2.90; 95% CI, 2.02 to 4.15; P = 3.2 × 10⁻⁹). A total of 48.2% of individuals with severe, extremely treatment-resistant schizophrenia carried at least one rare, damaging missense or loss-of-function variant in intolerant genes compared to 29.8% of typical schizophrenia individuals (odds ratio, 2.18; 95% CI, 1.33 to 3.60; P = 1.6 × 10⁻³) and 25.4% of controls (odds ratio, 2.74; 95% CI, 1.85 to 4.06; P = 2.9 × 10⁻⁷). Restricting to genes previously associated with schizophrenia risk strengthened the enrichment with 8.9% of individuals with severe, extremely treatment-resistant schizophrenia carrying a damaging missense or loss-of-function variant compared to 2.3% of typical schizophrenia (odds ratio, 5.48; 95% CI, 1.52 to 19.74; P = 0.02) and 1.6% of controls (odds ratio, 5.82; 95% CI, 3.00 to 11.28; P = 2.6 × 10⁻⁸). These results demonstrate the power of extreme phenotype case selection in psychiatric genetics and an approach to augment schizophrenia gene discovery efforts.

Schizophrenia affects nearly 1% of the population (1) and has sufficiently high heritability (80%) (2) to suggest that identifying genetic risk factors would provide insights into disease mechanisms. Yet, with one exception (3), definitively linking the hundreds of schizophrenia-associated common variant loci (4) to the pathophysiology of the disorder has been difficult. A more direct path to understanding the molecular basis of schizophrenia would come from the identification of highly penetrant rare variants in single genes, but this approach has so far been challenging. The Schizophrenia Exome Sequencing Meta-Analysis (SCHEMA) consortium recently conducted the largest sequencing study of schizophrenia to date, analyzing over 24,000 cases and identified 10 genes with a statistically significant excess of rare variants (5). While this represents a significant step forward, this yield is low compared to the hundreds of genes discovered in other neuropsychiatric disorders such as developmental delay and autism spectrum disorder (6, 7).In many complex genetic disorders, individuals with more severe or earlier-onset manifestations are more likely to harbor rare, deleterious variants of large effect (8–11). As a consequence, extreme phenotype sampling—selecting individuals at the extreme ends of the distribution of a phenotypic trait—substantially reduces the sample size needed to identify genetic causes of disease (12). Sequencing studies of extreme phenotype cohorts have successfully identified rare variants of large effect in hypercholesterolemia (10), epilepsy (9), autism (11), childhood-onset schizophrenia (8, 13), and other conditions. We therefore applied this approach in a sequencing study of individuals with severe, extremely treatment-resistant schizophrenia.Our primary analyses focused on testing for an enrichment of rare loss-of-function and damaging missense variants across “intolerant” genes. Intolerant genes are significantly depleted of functional variation (i.e., missense and loss-of-function) in healthy populations and are under strong negative selection as they are associated with a significant reduction in fecundity (14). Prior studies of schizophrenia have shown that the case-control burden of rare loss-of-function (odds ratio, 1.26) and damaging missense variants (odds ratio, 1.06 to 1.25) is concentrated exclusively in intolerant genes (5, 15). Using an extreme phenotype sequencing approach, we identified the highest burden of rare variants reported in the schizophrenia literature to date, suggesting that careful phenotype selection can augment gene discovery efforts in psychiatric genetics.     

The clinical and epidemiologic features in 140 patients with lupus nephritis in a predominantly black population from one center in Kingston, Jamaica

BACKGROUND: Lupus nephritis has emerged as a major factor in the overall survival of patients and may help to explain the poor prognosis associated with systemic lupus erythematosus (SLE) in black patients. METHODS: The authors reviewed the clinical and epidemiologic features of lupus nephritis in 130 women and 10 men who were mainly of African descent. RESULTS: The mean (standard deviation) age at diagnosis of SLE was 27.9 (10.3) years. The majority of patients (75%) developed renal involvement within 1 year of presentation with SLE. The most frequent extrarenal manifestations were arthritis (67%), malar rash (44%), serositis (41%), and neurologic disorders (30%). Class IV nephritis was the most common glomerular lesion, accounting for 49% of the biopsies, with class II accounting for a further 23%. Proteinuria was a common feature at presentation in all classes. Nephrotic range proteinuria was most common in classes III and IV. Prevalence of nephrotic range proteinuria was similar in classes II (23%) and V (19%). Hematuria occurred in more than one half of the patients with classes II, IV, and V disease. Fifty-nine percent of the patients had renal impairment at the time of renal biopsy. The prevalence of hypertension, the nephritic syndrome, and renal impairment was significantly higher in class IV patients compared with all the other groups. Factors that were significantly associated with classes III and IV disease compared with the other classes on univariate analysis were renal impairment, proteinuria (but not in nephrotic range), low C3 levels, and anemia. CONCLUSIONS: The clinical features of the study patients were similar to those of patients belonging to other ethnic groups, but a high proportion of the study patients had renal impairment at the time of renal biopsy.     

Integrating person-centered and variable-centered analyses: growth mixture modeling with latent trajectory classes

BACKGROUND: Many alcohol research questions require methods that take a person-centered approach because the interest is in finding heterogeneous groups of individuals, such as those who are susceptible to alcohol dependence and those who are not. A person-centered focus also is useful with longitudinal data to represent heterogeneity in developmental trajectories. In alcohol, drug, and mental health research the recognition of heterogeneity has led to theories of multiple developmental pathways. METHODS: This paper gives a brief overview of new methods that integrate variable- and person-centered analyses. Methods discussed include latent class analysis, latent transition analysis, latent class growth analysis, growth mixture modeling, and general growth mixture modeling. These methods are presented in a general latent variable modeling framework that expands traditional latent variable modeling by including not only continuous latent variables but also categorical latent variables. RESULTS: Four examples that use the National Longitudinal Survey of Youth (NLSY) data are presented to illustrate latent class analysis, latent class growth analysis, growth mixture modeling, and general growth mixture modeling. Latent class analysis of antisocial behavior found four classes. Four heavy drinking trajectory classes were found. The relationship between the latent classes and background variables and consequences was studied. CONCLUSIONS: Person-centered and variable-centered analyses typically have been seen as different activities that use different types of models and software. This paper gives a brief overview of new methods that integrate variable- and person-centered analyses. The general framework makes it possible to combine these models and to study new models serving as a stimulus for asking research questions that have both person- and variable-centered aspects.     

Immunodiagnosis of human hydatid disease

A study was undertaken to evaluate the efficacy of Enzyme Linked Immunosorbent Assay using locally prepared antigens for immunodiagnosis of human hydatid disease. A total of 90 cases clinically suspected to be suffering from hydatid disease and 100 controls matched for age and sex were included in the study. Two types of ELISA were performed on detected specific antihydatid antibodies belonging to IgG/IgM/IgA classes and other type detected IgE class of antibodies. Antigen prepared from the human hydatid fluid was found to be unsuitable for diagnosis as it contained host proteins i.e. IgG. Sheep hydatid fluid obtained from the fertile hydatid cyst was used to prepare and standardize the antigen. ELISA test to detect anti hydatid antibodies belonging to either IgG, IgM and or IgA was found to be highly specific (98 per cent) in surgically confirmed hydatid disease and was negative in all the controls. The results of the study indicate that ELISA along with casoni test may provide the best results in diagnosis of hydatid disease.     

Unique plasma metabolomic signatures of individuals with inherited disorders of long-chain fatty acid oxidation

Blood and urine acylcarnitine profiles are commonly used to diagnose long-chain fatty acid oxidation disorders (FAOD: i.e., long-chain hydroxy-acyl-CoA dehydrogenase [LCHAD] and carnitine palmitoyltransferase 2 [CPT2] deficiency), but the global metabolic impact of long-chain FAOD has not been reported. We utilized untargeted metabolomics to characterize plasma metabolites in 12 overnight-fasted individuals with FAOD (10 LCHAD, two CPT2) and 11 healthy age-, sex-, and body mass index (BMI)-matched controls, with the caveat that individuals with FAOD consume a low-fat diet supplemented with medium-chain triglycerides (MCT) while matched controls consume a typical American diet. In plasma 832 metabolites were identified, and partial least squared-discriminant analysis (PLS-DA) identified 114 non-acylcarnitine variables that discriminated FAOD subjects and controls. FAOD individuals had significantly higher triglycerides and lower specific phosphatidylethanolamines, ceramides, and sphingomyelins. Differences in phosphatidylcholines were also found but the directionality differed by metabolite species. Further, there were few differences in non-lipid metabolites, indicating the metabolic impact of FAOD specifically on lipid pathways. This analysis provides evidence that LCHAD/CPT2 deficiency significantly alters complex lipid pathway flux. This metabolic signature may provide new clinical tools capable of confirming or diagnosing FAOD, even in subjects with a mild phenotype, and may provide clues regarding the biochemical and metabolic impact of FAOD that is relevant to the etiology of FAOD symptoms.     

Phenotypic and functional deficiencies of leukaemic dendritic cells from patients with chronic myeloid leukaemia

Chronic myeloid leukaemia (CML) dendritic cells (DC) are possible candidates for inducing antileukaemic immunity. This study aimed to investigate the frequency, phenotype and function of blood-derived leukaemic DC in comparison with DC from healthy donors using flow cytometric assays and mixed leucocyte reaction (MLR). Immature leukaemic DC displayed a reduced endocytotic capacity as compared with healthy controls. Moreover, in vitro maturation of leukaemic DC was found to be deficient. Expression of CD80, CD83, CD86, and major histocompatibility complex class I and class II antigens were reduced on lipopolysaccharide (LPS)-matured leukaemic DC but were enhanced by a mixture of interleukin 1beta (IL-1beta), IL-6, tumour necrosis factor-alpha (TNF-alpha) and prostaglandin E2 (PGE2). Upon stimulation with bacterial LPS, intracellular TNF-alpha and IL-8 production was diminished in maturing DC from CML patients. This distinct cytokine deficiency was overcome when leukaemic DC were stimulated with cytokines/PGE2. MLR showed fully functional leukaemic DC after TNF-alpha-induced maturation, but a reduced proliferative alloresponse of leukaemic peripheral blood mononuclear cells. Further, intracellular production of cytokines in CML-derived T cells was markedly reduced. These data indicated that, in CML, the maturation response of leukaemic monocyte-derived DC to a natural stimulus like LPS is abnormal and may be caused by an aberrant TNF-alpha response in these cells. Thus, TNF-alpha alone or in combination with pro-inflammatory and T-cell stimulatory cytokines should be considered as an adjuvant for DC-based immunotherapy in CML.     

Serum Metabolic Profiling in Inflammatory Bowel Disease

Background

The inflammatory bowel diseases (IBD), Crohn’s disease (CD), and ulcerative colitis (UC), are chronic inflammatory conditions of the gastrointestinal tract whose pathogenesis is not completely understood. ¹H nuclear magnetic resonance (NMR) spectroscopy of serum generates comprehensive metabolic profiles, reflecting systemic metabolism, which may be altered in disease states.

Aim

The aim of this study was to use ¹H NMR-based serum metabolic profiling in the investigation of CD patients, UC patients, and controls, potentially to provide insights into disordered metabolism in IBD, and into underlying mechanisms of disease.

Methods

Serum metabolic profiles were acquired from 67 individuals (24 CD patients, 20 UC patients, and 23 healthy controls). The multivariate pattern-recognition techniques of principal components analysis (PCA) and partial least squares discriminant analysis with orthogonal signal correction (OSC-PLS-DA) were used to investigate differences between cohorts.

Results

OSC-PLS-DA distinguished CD and UC cohorts with significant predictive accuracy, highlighting differences in lipid and choline metabolism. Metabolic profiles of both CD and UC cohorts, and the combined IBD cohort, differed significantly from controls: metabolites of importance in the OSC-PLS-DA models included lipoproteins (especially HDL cholesterol), choline, N-acetylglycoprotein, and amino acids.

Conclusions

¹H NMR-based metabolic profiling has identified distinct differences in serum metabolic phenotype between CD and UC patients, as well as between IBD patients and controls.     

Clinical and immunogenetic features of patients with autoantibodies to asparaginyl–transfer RNA synthetase

Objective

We have previously described anti‐KS autoantibodies and provided evidence that they are directed against asparaginyl–transfer RNA (tRNA) synthetase (AsnRS). The aim of the present study was to identify patients with anti‐AsnRS autoantibodies and elucidate the clinical significance of this sixth antisynthetase antibody. In particular, we studied whether it was associated with the syndrome of myositis (polymyositis or dermatomyositis [DM]), interstitial lung disease (ILD), arthritis, and other features that had been previously associated with the 5 other anti–aminoacyl–tRNA synthetase autoantibodies.

Methods

More than 2,500 sera from patients with connective tissue disease (including myositis and ILD) and controls were examined for anti‐AsnRS autoantibodies by immunoprecipitation (IP). Positive and control sera were tested for the ability to inhibit AsnRS by preincubation of the enzyme source with the serum. The HLA class II (DRB1, DQA1, DQB1, DPB1) alleles were identified from restriction fragment length polymorphism of polymerase chain reaction–amplified genomic DNA.

Results

Anti‐AsnRS antibodies were identified in the sera of 8 patients (5 Japanese, 1 American, 1 German, and 1 Korean) by IP of the same distinctive set of tRNA and protein that differed from those precipitated by the other 5 antisynthetases, and these antibodies showed specific inhibition of AsnRS activity. Two of these patients had DM, but 7 of 8 (88%) had ILD. Four patients (50%) had arthritis, and 1 had Raynaud's phenomenon. This antisynthetase was very rare among myositis patients (present in 0% of Japanese myositis patients), but it was found in 3% of Japanese ILD patients. Thus, most patients with anti‐AsnRS had chronic ILD with or without features of connective tissue disease. Interestingly, all 4 Japanese patients tested had DR2 (DRB1*1501/1502), compared with 33% of healthy controls.

Conclusion

These results indicate that anti‐AsnRS autoantibodies, like anti–alanyl–tRNA synthetase autoantibodies, have a stronger association with ILD than with myositis and may be associated with the DR2 phenotype.

     

VA and Medicare Utilization Among Dually Enrolled Veterans with Type 2 Diabetes: A Latent Class Analysis

BACKGROUND

Many Veterans treated within the VA Healthcare System (VA) are also enrolled in fee-for-service (FFS) Medicare and receive treatment outside the VA. Prior research has not accounted for the multiple ways that Veterans receive services across healthcare systems.

OBJECTIVE

We aimed to establish a typology of VA and Medicare utilization among dually enrolled Veterans with type 2 diabetes.

DESIGN

This was a retrospective cohort.

PARTICIPANTS

316,775 community-dwelling Veterans age ≥ 65 years with type 2 diabetes who were dually enrolled in the VA and FFS Medicare in 2008–2009.

METHODS

Using latent class analysis, we identified classes of Veterans based upon their probability of using VA and Medicare diabetes care services, including patient visits, laboratory tests, glucose test strips, and medications. We compared the amount of healthcare use between classes and identified factors associated with class membership using multinomial regression.

KEY RESULTS

We identified four distinct latent classes: class 1 (53.9 %) had high probabilities of VA use and low probabilities of Medicare use; classes 2 (17.2 %), 3 (21.8 %), and 4 (7.0 %) had high probabilities of VA and Medicare use, but differed in their Medicare services used. For example, Veterans in class 3 received test strips exclusively through Medicare, while Veterans in class 4 were reliant on Medicare for medications. Living ≥ 40 miles from a VA predicted membership in classes 3 (OR 1.1, CI 1.06–1.15) and 4 (OR 1.11, CI 1.04–1.18), while Medicaid eligibility predicted membership in class 4 (OR 4.30, CI 4.10–4.51).

CONCLUSIONS

Veterans with diabetes can be grouped into four distinct classes of dual health system use, representing a novel way to characterize how patients use multiple services across healthcare systems. This classification has applications for identifying patients facing differential risk from care fragmentation.

     

Specific interactions outside the proline-rich core of two classes of Src homology 3 ligands.

Two dodecapeptides belonging to distinct classes of Src homology 3 (SH3) ligands and selected from biased phage display libraries were used to investigate interactions between a specificity pocket in the Src SH3 domain and ligant residues flanking the proline-rich core. The solution structures of c-Src SH3 complexed with these peptides were solved by NMR. In addition to proline-rich, polyproline type II helix-forming core, the class I and II ligands each possesses a flanking sequence that occupies a large pocket between the RT and n-Src loops of the SH3 domain. Structural and mutational analyses illustrate how the two classes of SH3 ligands exploit a specificity pocket on the receptor differently to increase binding affinity and specificity.     

Medical comorbidity in women and men with schizophrenia

BACKGROUND: Persons with persistent mental illness are at risk for failure to receive medical services. In order to deliver appropriate preventive and primary care for this population, it is important to determine which chronic medical conditions are most common. OBJECTIVE: We examined chronic medical comorbidity in persons with schizophrenia using validated methodologies. DESIGN: Retrospective analysis of longitudinal administrative claims data from Wellmark Blue Cross/Blue Shield of Iowa. PARTICIPANTS: Subjects with schizophrenia or schizoaffective disorder (N=1,074), and controls (N=726,262) who filed at least 1 claim for medical services, 1996 to 2001. MEASUREMENTS: Case subjects had schizophrenia as the most clinically predominant psychotic disorder, based on psychiatric hospitalization, psychiatrist diagnoses, and outpatient care. Controls had no claims for any psychiatric comorbidity. Using a modified version of the Elixhauser Comorbidity Index, inpatient and outpatient claims were used to determine the prevalence of 46 common medical conditions. Odds ratios (ORs) were adjusted for age, gender, residence, and nonmental health care utilization using logistic regression. RESULTS: Subjects with schizophrenia were significantly more likely to have 1 or more chronic conditions compared with controls. Adjusted OR (95% confidence interval [CI]) were 2.62 (2.09 to 3.28) for hypothyroidism, 1.88 (1.51 to 2.32) for chronic obstructive pulmonary disease, 2.11 (1.36 to 3.28) for diabetes with complications, 7.54 (3.55 to 15.99) for hepatitis C, 4.21 (3.25 to 5.44) for fluid/electrolyte disorders, and 2.77 (2.23 to 3.44) for nicotine abuse/dependence. CONCLUSIONS: Schizophrenia is associated with substantial chronic medical burden. Familiarity with conditions affecting persons with schizophrenia may assist programs aimed at providing medical care for the mentally ill.     

Molecular consequences of cystic fibrosis transmembrane regulator (CFTR) gene mutations in the exocrine pancreas

BACKGROUND AND AIMS: We tested the hypothesis that the actual or predicted consequences of mutations in the cystic fibrosis transmembrane regulator gene correlate with the pancreatic phenotype and with measures of quantitative exocrine pancreatic function. METHODS: We assessed 742 patients with cystic fibrosis for whom genotype and clinical data were available. At diagnosis, 610 were pancreatic insufficient, 110 were pancreatic sufficient, and 22 pancreatic sufficient patients progressed to pancreatic insufficiency after diagnosis. RESULTS: We identified mutations on both alleles in 633 patients (85.3%), on one allele in 95 (12.8%), and on neither allele in 14 (1.9%). Seventy six different mutations were identified. The most common mutation was DeltaF508 (71.3%) followed by G551D (2.9%), G542X (2.3%), 621+1G-->T (1.2%), and W1282X (1.2%). Patients were categorized into five classes according to the predicted functional consequences of each mutation. Over 95% of patients with severe class I, II, and III mutations were pancreatic insufficient or progressed to pancreatic insufficiency. In contrast, patients with mild class IV and V mutations were consistently pancreatic sufficient. In all but four cases each genotype correlated exclusively with the pancreatic phenotype. Quantitative data of acinar and ductular secretion were available in 93 patients. Patients with mutations belonging to classes I, II, and III had greatly reduced acinar and ductular function compared with those with class IV or V mutations. CONCLUSION: The predicted or known functional consequences of specific mutant alleles correlate with the severity of pancreatic disease in cystic fibrosis.     

Molecular typing of candida albicans isolated from oral lesions of HIV-infected individuals.

OBJECTIVE: To evaluate the epidemiology of Candida albicans infection in HIV-infected patients with oral lesions using molecular techniques. METHODS: Thirty-nine isolates from HIV-positive patients with oral candidiasis were examined using two DNA probes (a Histoplasma capsulatum ribosomal DNA probe that cross-hybridizes with C. albicans and a C. albicans strain-specific probe derived from repetitive sequence DNA). C. albicans obtained from the oral cavity of patients receiving cytotoxic chemotherapy was used as controls. RESULTS: Using the H. capsulatum ribosomal DNA probe, isolates were shown to members of many distinct classes of C. albicans. Forty-nine per cent (19 out of 39) of isolates were members of the same class; however, 46% (6 out of 13) of control C. albicans isolates were also members of this class. Further analysis of the class-restricted isolates from the HIV-infected patients using the C. albicans strain-specific probe showed that these could be further separated into distinct strains. CONCLUSIONS: These data indicate that strains of C. albicans that cause oral candidiasis in HIV-positive individuals are not clonally restricted and are similar to those colonizing the oral cavity of other severely immunocompromised hosts. Most patients appear to be infected with unique strains of C. albicans.     

Association of human leukocyte antigen class II genes with autoantibody profiles, but not with disease susceptibility in Japanese patients with systemic sclerosis.

OBJECT: To examine the role of human leukocyte antigen (HLA) class II genes in the development of systemic sclerosis (SSc) as well as in the clinical and serologic expression of SSc in patients. METHODS: HLA-DRB1, DRB3, DRB4, DQB1, and DPB1 alleles were determined by genotyping; and serum antinuclear antibodies were identified using indirect immunofluorescence, double immunodiffusion and immunoprecipitation. PATIENTS: One hundred and five Japanese patients with SSc and 104 race-matched healthy controls. RESULTS: Frequencies of DRB1 and DQB1 alleles were not different between SSc patients and healthy controls, while DPB1*0901 was marginally increased in SSc patients. In contrast, SSc-related autoantibodies were closely associated with the clinical features. HLA class II genes were detected as follows: anti-DNA topoisomerase I antibody with diffuse cutaneous involvement, pulmonary fibrosis, and DRB1*1502-DQB1*0601-DPB1*0901; anti-U1RNP antibody with overlapping features of lupus and/or myositis and DRB1*0401/*0802-DQB1*0302; and anticentromere antibody with limited cutaneous involvement and DRB1*0101-DQB1*0501-DPB1*0402. In the analysis of the association of HLA class II and the clinical features in SSc patients significant differences were obtained only for the increased frequencies of arthritis and rheumatoid factor in patients with DRB1*0405 compared to those without. CONCLUSION: HLA class II genes strongly influence the production of SSc-related autoantibodies rather than the development of SSc. In addition, SSc is a composite disease of distinctive subsets defined by serum autoantibodies, which have specific clinical and HLA class II associations.     

Genetic analysis of developmental stages of the cellular slime mold Dictyostelium purpureum

71 Mutants of Dictyostelium purpureum, unable to carry out normal development, were isolated. These mutants fall into three phenotypic classes. The mutants of the first class do not aggregate. Those of the second class develop a little further and form conical aggregates. The mutants of the third class progress still further, and the conical aggregates are transformed into finger-shaped masses, but no fruiting bodies are formed. Mutants of each class were able to form fruiting bodies when mixed with mutants of other classes. Pairs of mutants belonging to the same class, however, never responded synergistically. This result indicates the presence of three distinct developmental stages in the process of the fruiting-body formation. Experiments with actinomycin D suggested that genes controlling the developmental process of D. purpureum were divided into three groups which were identical to those identified by the analysis of synergism.