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Ultradian rapid cycling in prepubertal and early adolescent bipolarity is not in transmission disequilibrium with val/met COMT alleles.

BACKGROUND: Prepubertal children and early adolescents with bipolar disorders (PEA-BP) who participate in the ongoing study "Phenomenology and Course of Pediatric Bipolar Disorders" have a high prevalence of ultradian (within 24-hour periods) rapid cycling. Based on a case-control finding reported in bipolar (BP) adults of an association between rapid and ultradian rapid cycling with the low-activity allele of catechol-O-methyltransferase (l-COMT), study of linkage and linkage disequilibrium of l-COMT in the PEA-BP population seemed warranted. METHODS: Genotypes on a subset of the larger PEA-BP sample, for whom trio blood collection was complete (i. e., probands and both of their biological parents), were used to perform transmission disequilibrium tests (TDTs). Diagnoses were established from a comprehensive battery that included WASH-U-KSADS (Washington University Kiddie Schedule for Affective Disorders and Schizophrenia) given to both mothers and children and from consensus conferences. Probands with PEA-BP (N = 52) were 10.9 +/- 2.8 years old at index episode; had a mean age of BP onset at 8.0 +/- 3.8 years; were severely impaired, with a mean Children's Global Assessment Scale score of 44.5 +/- 8.9; and manifested the cardinal features of BP (84.6% had euphoric mood, 76.9% had grandiosity, and 57.7% had psychosis). Ultradian rapid cycling occurred in 75%. Genotyping of the single nucleotide polymorphism at COMT was performed using automated capillary electrophoresis single-strand conformational polymorphism with detection by laser-induced fluorescence. RESULTS: Transmission disequilibrium tests were not significant for preferential transmission of l-COMT for the ultradian rapid-cycling subgroup or for the entire PEA-BP sample. CONCLUSIONS: The lack of linkage disequilibrium between l-COMT and ultradian rapid cycling in the PEA-BP sample compared to reported findings of an association in case-control studies of adults is discussed in terms of age-specific developmentally relevant phenotypes, anticipatory mechanisms, and heterogeneity. Repeat TDT analyses after these PEA-BP probands reach their adult phenotypes will be informative.

Adolescent↗

Molecular genetic analysis of two functional candidate genes in the autosomal recessive retinitis pigmentosa, RP25, locus.

PURPOSE: To identify the disease gene in five Spanish families with autosomal recessive retinitis pigmentosa (arRP) linked to the RP25 locus. Two candidate genes, EEF1A1 and IMPG1, were selected from the region between D6S280 and D6S1644 markers where the families are linked. The genes were selected as good candidates on the basis of their function, tissue expression pattern, and/or genetic data. METHODS: A molecular genetic study was performed on DNA extracted from one parent and one affected member of each studied family. The coding exons, splice sites, and the 5' UTR of the genes were amplified by polymerase chain reaction (PCR). For mutation detection, direct sequence analysis was performed using the ABI 3100 automated sequencer. Segregation of an IMPG1 single nucleotide polymorphism (SNP) in all the families studied was analyzed by restriction enzyme digest of the amplified gene fragments. RESULTS: In total, 15 SNPs were identified of which 7 were novel. Of the identified SNPs, one was insertion, two were deletions, five were intronic, six were missense, and one was located in the 5' UTR. These changes, however, were also identified in unaffected members of the families and/or 50 control Caucasians. The examined known IMPG1 SNP was not segregating with the disease phenotype but was correlating with the genetic data in all families studied. CONCLUSIONS: Our results indicate that neither EEF1A1 nor IMPG1 could be responsible for RP25 in the studied families due to absence of any pathogenic variants. However, it is important to notice that the methodology used in this study cannot detect larger deletions that lie outside the screened regions or primer site mutations that exist in the heterozygous state. A role of both genes in other inherited forms of RP and/or retinal degenerations needs to be elucidated.

Chromosome Mapping↗

Erythropoietic protoporphyria: identification of novel mutations in the ferrochelatase gene and comparison of biochemical markers versus molecular analysis as diagnostic strategies.

BACKGROUND: Erythropoietic protoporphyria (EPP) results from an inherited deficiency of the last enzyme of the heme biosynthetic pathway, ferrochelatase (FC). EPP is usually inherited in an autosomal dominant fashion, and the mutations in the FC gene on chromosome 18q21.3 detected in EPP patients are heterogeneous. METHODS: In this study, we screened the FC gene for mutations in 12 patients from 10 unrelated families with EPP and their family members using heteroduplex analysis, automated sequencing, and restriction enzyme digestion. RESULTS: We detected 8 different mutations in these patients, including 1 missense mutation, 5 frameshift mutations, and 2 splice site mutations, 6 of which are previously undescribed. CONCLUSIONS: We have established the molecular basis of EPP in 10 unrelated families, thereby providing further evidence for the heterogeneity in this disorder. Importantly, molecular diagnosis allowed revisions in the status of several clinically unaffected silent mutation carriers within the families. We compare the value of genetic research strategies with the combination of biochemical data and clinical phenotype as diagnostic tools to confirm a putative diagnosis in EPP.

Biomarkers↗

Cholinesterase assay automated in the Cobas-Bio centrifugal analyzer.

We describe a method for measuring plasma cholinesterase (EC 3.1.1.8) and dibucaine and fluoride numbers by using the Cobas-Bio. Benzoyl choline chloride is used as substrate. Reaction conditions are the same as in the corresponding manual method. The reaction is stopped with physostigmine. Choline oxidase (EC 1.1.3.17) is coupled with 4-aminoantipyrene. In the presence of peroxidase (EC 1.11.1.7), the 2-hydroxy-3,5-dichlorobenzenesulfonate indicator reaction gives a red product, measured at 505 nm. The analyzer is used in the "Multi Run" mode, with plasma cholinesterase and dibucaine and fluoride inhibition concurrently measured for eight samples. Coefficients of correlation between the manual and present method for plasma cholinesterase and dibucaine and fluoride numbers in 40 patients of various phenotypes were 0.843, 0.923, and 0.717, respectively. The inter-batch CV for each of the three assays was 2% to 3%.

Autoanalysis↗

A pentaplex automated fluorescent typing system for forensic identification and French Caucasian population data.

The polymerase chain reaction (PCR) amplification of short tandem repeat (STR) loci has already proven to be a method of choice for large scale typing of DNA samples in which the conventional restriction fragment length polymorphism (RFLP) technique is ineffective. A quadruplex PCR including HUMvWFA31A, HUMF13A01, HUMTH01, and HUMFESFPS STR loci is used successfully for routine forensic applications in our laboratory. However, the need to increase the discrimination power of the PCR systems used prompted us to develop a second system of a pentaplex PCR for the analysis of 4 additional STR loci (HUMD8S1179, HUMD18S51, HUMD21S11, and HUMFIBRA) and the sex determination by amplification of a segment of the X-Y homologous Amelogenin gene. Allele and phenotype frequencies for these 4 STR systems were obtained by multiplex amplification, from approximately 200 randomly selected and unrelated French Caucasian individuals. Statistical calculations for these phenotype distributions met expectations for Hardy-Weinberg equilibrium. Furthermore, the French allelic frequencies of D18S51, D21S11, and HUMFIBRA loci were compared with the data obtained by the Forensic Science Service (UK) for the British Caucasian population and proved to be similar.

Alleles↗

Cleaning genotype data.

The identification of genes contributing to variation in complex phenotypes requires genetic data of high fidelity. Thus, the identification of pedigree and genotyping errors is a crucial prerequisite to the analysis of data from a genome scan for disease genes. The problem has been given little attention in most gene hunting papers; the focus has often been on eliminating mendelian inconsistencies in order that the analysis may proceed, rather than on achieving the best possible data. Though a number of computer programs are available to assist in the identification of genotyping and pedigree errors, the process is still not completely automated. While the Collaborative Study on the Genetics of Alcoholism (COGA) data set for GAW11 is completely compatible with Mendel's rules, there are still some errors present. We inspected the COGA data for the presence of additional errors, and identified five possible pedigree errors.

Alcoholism↗

Prenatal and postnatal diagnoses of thalassemias and hemoglobinopathies by HPLC.

The conventional approach to qualitative and quantitative analyses of hemoglobin (Hb) molecules for the diagnoses of hemoglobinopathies requires a combination of tests. We used an automated HPLC (VARIANT) system to study alpha-thalassemia and beta-thalassemia syndromes in Thailand. The beta-thalassemia short program is applicable to the diagnosis of alpha-thalassemia and beta-thalassemia disorders, including Hb H, EA Bart's disease, and EF Bart's disease, in adults, newborns, and fetuses. The system cannot quantify accurately certain Hb molecules, such as Hb H and Hb Bart's. The alpha-thalassemia short program was therefore developed and used to quantify Hb Bart's to detect alpha-thalassemia genotypes in cord blood. This automated HPLC system is an alternative approach to the diagnosis of complicated thalassemia syndromes in Thailand and Southeast Asia.

Adult↗

Identification of novel cellular genes transcriptionally suppressed by v-src.

Our aim is to identify cellular genes whose transcriptional suppression by the v-src oncogene contributes directly and specifically to the transformed and tumorigenic phenotype. We used a modified PCR-based subtractive hybridization technique to isolate 9 cDNAs whose abundance in NIH3T3 fibroblasts is decreased 3-15-fold following transformation by the activated oncogene, v-src. Sequence analysis reveals that 3 cDNAs are unlike those in GenBank. The remaining 6 cDNAs are indentical or highly similar to rat helix-destabilizing protein gene (hnRNP A1), mouse CTLA-2 alpha cysteine protease, rat cytochrome c oxidase (COX) VIc subunit, mouse Type I collagen, human gravin and a partial human cDNA (clone A7C09) isolated by random automated sequencing. Northern blot analysis indicates that the basal level of transcripts in untransformed NIH3T3 of all the genes except mouse Type I collagen was at least 10-fold lower than that of HMG Co-A Reductase, which is abundantly transcribed. These data suggest that the down-regulation of some or all of these genes contributes to v-src-induced changes in mitogenic control or cell morphology.

3T3 Cells↗

An uncoupling protein 2 gene variant is associated with a raised body mass index but not Type II diabetes.

AIMS/HYPOTHESIS: Linkage between markers close to the uncoupling protein 2 and 3 genes (11q13) and resting metabolic rate and a pre-diabetic phenotype have been found. The syntenic region in mouse has been found to be linked to quantitative traits associated with obesity and diabetes. UCP2 and UCP3 could therefore have an important role in body weight regulation and susceptibility to diabetes. We investigated a recently identified variant of the UCP2 gene in exon 8 as a marker for glucose and weight homeostasis. METHODS: Length variation of the UCP2 exon 8 variant was studied by the polymerase chain reaction and agarose gel electrophoresis. Sequence variants of the UCP3 gene were sought by semi-automated DNA sequencing. RESULTS: In 453 South Indian subjects, we found an association in women between the UCP2 exon variant and body mass index (p = 0.018). These findings were replicated in a separate group of South Indian subjects (n = 143, p < 0.001) irrespective of sex. Although no association was found between the UCP2 exon 8 variant and overt obesity in British subjects, the UCP2 genotype of obese women (n = 83) correlated with fasting serum leptin concentration (p = 0.006) in the presence of extreme obesity. These observations could not be explained by tight linkage disequilibrium with a coding region variant in the region of the UCP3 gene of biological significance. Lastly, no association was found between UCP2 and Type II (non-insulin-dependent) diabetes using either a family based design (85 families) or case control study (normal glucose tolerance n = 335, impaired glucose tolerance n = 42, Type II diabetes n = 76). CONCLUSION/INTERPRETATION: We have described a UCP2 gene exon 8 variant that may affect susceptibility to weight gain by influencing regulation of leptin.

Adult↗

Classification of abnormal fundus autofluorescence patterns in the junctional zone of geographic atrophy in patients with age related macular degeneration.

AIM: To describe and classify patterns of abnormal fundus autofluorescence (FAF) in the junctional zone of geographic atrophy (GA) in patients with age related macular degeneration. METHODS: Digital FAF images were recorded in 164 eyes of 107 patients using a confocal scanning laser ophthalmoscope (cSLO; excitation 488 nm, detection above 500 nm) as part of a prospective multicentre natural history study (FAM Study). FAF images were obtained in accordance with a standardised protocol for digital image acquisition and generation of mean images after automated alignment. RESULTS: Image quality was sufficient for classification of FAF patterns in 149 eyes (90.9%) with lens opacities being the most common reason for insufficient image quality. Abnormal FAF outside GA in 149 eyes was classified into four patterns: focal (12.1%), banded (12.8%), patchy (2.0%), and diffuse (57.0%), whereby 12.1% had normal background FAF in the junctional zone. In 4% there was no predominant pattern. The diffuse pattern was subdivided into four groups including reticular (4.7%), branching (27.5%), fine granular (18.1%), and fine granular with peripheral punctate spots (6.7%). CONCLUSIONS: Different phenotypic patterns of abnormal FAF in the junctional zone of GA can be identified with cSLO FAF imaging. These distinct patterns may reflect heterogeneity at a cellular and molecular level in contrast with a non-specific ageing process. A refined phenotypic classification may be helpful to identify prognostic determinants for the spread of atrophy and visual loss, for identification of genetic risk factors as well as for the design of future interventional trials.

Aged↗

Data acquisition, data storage, and data presentation in a modern genetics laboratory.

Modern genetic analysis can be divided into three main areas of investigation. The first is data acquisition, in the form of genomic sequence and the cataloguing of polymorphism data of the single nucleotide polymorphism variety (so called SNPs). Once identified, such genetic information can be adapted into high throughput tests to examine genetic information in large populations, making the analysis of sufficiently large numbers both cost and time effective so that relatively low-penetrant genetic effects can be accurately detected. The third step is correlating variation with phenotype (e.g. disease susceptibility or resistance) for a variety of disorders is paramount in our motivation and indeed is a common goal of modern human genetic analysis. While the technology to acquire vast amounts of genetic data is now well established and continues to expand, the ability to deal with such data, from the process of acquisition, storage, and analysis depends fundamentally on a solid informatics infrastructure as an essential component. Indeed, most of the major gains in productivity in this field are to be realized on the informatics front, and involve automating data acquisition, defining and sorting data in databases for quality control and analysis and facilitating access to data for the large variety of data analyses. Informatics-related issues including those relating to data acquisition, database structure, and analysis tools are summarized here in an effort to define some of the issues relevant to establishing informatics infrastructure in a small genetics laboratory focused on resequencing human immune response genes. From inherited diseases to drug efficacy to the specific genetic changes occurring during tumor development, this new field of medical genetics promises a profound impact on the state of human health. Ultimately, any and all advances in this field will continue to depend on major investments in informatics.

Computational Biology↗

The molecular basis of phenylketonuria in Lithuania.

We report the spectrum of phenylalanine hydroxylase (PAH) gene mutations in patients with phenylketonuria (PKU) residing in Lithuania. A total of 184 independent chromosomes was investigated. R408W mutation was first analysed through restriction enzyme digestion of exon 12. The remaining uncharacterised PKU chromosomes were analysed by scanning the whole coding sequence of PAH gene by multiplex 'broad range' denaturing gradient gel electrophoresis. Mutations were identified by fluorescent automated sequencing or by restriction enzyme digestion analysis if an abnormal DGGE pattern was recognised. 21 different mutations were identified for 175 PKU chromosomes, with a mutation detection rate of 95%. The most common ones were R408W (73.5% chromosomes) and R158Q (7.0% chromosomes) whereas the remaining mutations appeared to be rare (relative frequencies 0.5%-2%). The high mutation detection rate obtained is an evidence of the efficiency of PAH genetic testing achieved in Lithuania. Moreover, the definition of the PKU mutation profile in the Lithuanian population will allow to perform a genotype-phenotype correlation study thus making feasible genotyped-based prediction of the biochemical phenotype in newborns with hyperphenylalaninemia. This may be useful for refining diagnosis and anticipating dietary requirements.

Amino Acid Substitution↗

von Willebrand disease phenotype and von Willebrand factor marker genotype in Doberman Pinschers.

OBJECTIVE: To define the relationship between clinical expression of a type-1 von Willebrand disease phenotype and genotype at 2 von Willebrand factor marker loci in Doberman Pinschers. ANIMALS: 102 client-owned Doberman Pinschers. PROCEDURES: Dogs were recruited on the basis of plasma von Willebrand factor concentration, clinical history, and pedigree. Blood samples and response to a history questionnaire were obtained for each dog. Plasma von Willebrand factor concentration was measured by use of an ELISA, and genotyping was performed via polymerase chain reaction for 1 intragenic and 1 extragenic von Willebrand factor marker. Amplification product size was determined by use of polyacrylamide gel electrophoresis (intragenic marker) or automated sequence analysis (extragenic marker). Western blots were prepared from a subset of dogs with low plasma von Willebrand factor concentration to evaluate multimer distribution. RESULTS: Strong associations were detected between plasma von Willebrand factor concentration and von Willebrand factor marker genotype. Twenty-five dogs had substantial reduction in plasma von Willebrand factor concentration and multiple hemorrhagic events. All were homozygous for a 157-base-pair intragenic marker allele and homozygous or compound heterozygous for 1 of 4 extragenic marker alleles. These marker genotypes were exclusively detected in dogs with low plasma von Willebrand factor concentration, although some dogs with these genotypes did not have abnormal bleeding. CONCLUSIONS AND CLINICAL RELEVANCE: Type-1 von Willebrand disease in Doberman Pinschers is associated with the von Willebrand factor gene locus; however, the expression pattern in this breed appears more complex than that of a simple recessive trait.

Alleles↗

The genetic basis of "Scarsdale Gourmet Diet" variegate porphyria: a missense mutation in the protoporphyrinogen oxidase gene.

The porphyrias are disorders of porphyrin or porphyrin-precursor metabolism that result from inherited or acquired aberrations in the control of the porphyrin-heme biosynthetic pathway. Variegate porphyria (VP), one of the acute hepatic porphyrias, is characterized by a partial reduction in the activity of protoporphyrinogen oxidase (PPO), and recently, mutations in the PPO gene on chromosome 1q22-23 have been described. Our purpose was to identify the underlying genetic lesion in a severely affected patient with VP and to detect the silent mutation carriers in her family. The disease in this patient was precipitated by carbohydrate restriction as outlined in the "Scarsdale Gourmet Diet". Our mutation detection and confirmation strategy included PCR, automated sequencing, and restriction enzyme digestion. We identified a missense mutation in the patient and five family members. The mutation consisted of a previously unreported C-to-T transition in exon 5 of the PPO gene, resulting in the substitution of arginine by cysteine, designated R152C. This arginine residue is evolutionarily highly conserved in humans, mice, bacteria, yeast, and plants, indicating the importance of this residue in PPO. Our study established that a missense mutation in the PPO gene was the underlying mutation in this patient with VP and explained the occurrence of the phenotype in this family.

Amino Acid Sequence↗

[Impact of the removal of A2 test erythrocytes and the anti-AB reactant on the interpretation of the ABO blood grouping].

This work evaluates the impact of the removal of the anti-AB reagents and A2 test-red blood cells on the interpretation of ABO blood grouping. The first step of the work was a multicentric study concerning the interpretation of "all coming" blood groupings, reporting the results of 105 195 ABO blood groupings of donors and patients carried out on microplates using an automated or a half-automated technique. Their interpretation was performed following four different methods, in order to appreciate the impact on the results of the removal of either anti-AB test-serum, A2 test-red blood cells, or the combination of both. Moreover, a qualitative and quantitative analysis of the interpretations of the blood groupings that were initially not performed (rejections), was carried out in order to determine the most often implied reagent and to quantify a possible gain in interpretation after removing it. A complementary study of the same type concerning more specifically weak ABO phenotypes was carried out to evaluate, in terms of sanitary risks, the consequences of a possible non-interpretation of these phenotypes in patients who would be potential receivers of blood cell products, and in blood donors.

ABO Blood-Group System↗

Low frequency of microsatellite instability in sporadic breast cancer.

In some tumors, defects in mismatch repair enzymes lead to errors in the replication of simple nucleotide repeat segments. This condition is commonly known as microsatellite instability (MSI) because of the frequent mutations of microsatellite sequences. Although the MSI phenotype is well recognized in some colon, gastric, pancreatic, and endometrial cancers, reports of MSI in breast cancer are inconsistent. The purpose of this study was to determine the presence of MSI in breast cancer and to correlate its occurrence with clinicopathological parameters, including expression of estrogen and progesterone receptors. We have analyzed the status of 10 different microsatellite loci (mono and dinucleotide repeats). Mmicrosatellite size patterns and LOH were compared in 88 paired breast-cancer/peripheral-blood DNA samples. Fluorescent polymerase chain reaction (PCR) for typing microsatellites coupled with DNA fragment analysis in an automated DNA sequencer was applied. Microsatellite instability in at least two microsatellite markers was observed in 6 out of 88 (7%) of the cases, all beloging to stage II or III. LOH was found in 48/88 (55%) of the cases. Five of the six cases with MSI also had LOH in other markers different from those of MSI. These MI and LOH data were analysed using a range of clinicopathological parameters, no correlation between MSI and histopathological characteristics were found. A significant correlation was observed between MSI and negative expression of both estrogen and progesterone receptors (p<0.02), indicating a possible relatioship between specific genetic changes at these microsatellite regions and hormonal deregulation in the progresion of breast cancer.

Adult↗

Overexpression of transforming growth factor-alpha and epidermal growth factor-receptor in idiopathic pulmonary fibrosis.

BACKGROUND AND AIM: A recent transgenic mouse model overexpressing transforming growth factor alpha (TGF-alpha) led to a phenotype of pulmonary fibrosis. In order to validate this mouse as a model for idiopathic pulmonary fibrosis in humans, we studied the expression of TGF-alpha in lung tissue of patients with idiopathic pulmonary fibrosis compared to control lung tissue. METHODS: Tissue from both groups was obtained from operative specimens and immediately formalin-fixed and paraffin embedded. Contiguous four micron sections were prepared for conventional histochemical staining and staining with antibodies to either TGF-alpha or the epidermal growth factor-receptor (EGF-R). Immunostaining was performed using the Ventana ES automated immunohistochemistry system. Four cell types were examined (vascular endothelium, bronchial epithelium, type 2 pneumocytes, and fibroblasts) and stain activity was scored on a six point scale. RESULTS: Eleven patients with IPF were compared to seven control subjects. TGF-alpha immunoreactivity was significantly higher in the IPF patients than in controls in the vascular endothelium, type 2 pneumocytes, and fibroblasts (P < 0.005). [IPF (4(2-4) Median (Range)) than the controls (0.5(0-2), p < 0.0005).] The differences in EGF-R, one of the receptors for TGF-alpha, between these two patient populations were not as striking. There was a small but significantly greater expression of EGF-R in the bronchial epithelium and type 2 pneumocytes of the IPF patients. CONCLUSIONS: TGF-alpha is overexpressed in patients with IPF, especially in the vascular endothelial cells.

Adult↗

Microsatellite instability correlates with negative expression of estrogen and progesterone receptors in sporadic breast cancer.

In some tumors, defects in mismatch repair enzymes lead to errors in the replication of simple nucleotide repeat segments RER+ tumors. This condition is commonly known as microsatellite instability (MSI) because of the frequent mutations of microsatellite sequences. Although the MSI phenotype is well recognized in some colon, gastric, pancreatic, and endometrial cancers, reports of MSI in breast cancer are inconsistent. The purpose of this study was to determine the presence of MSI in breast cancer and to correlate its occurrence with clinicopathological parameters, including expression of estrogen and progesterone receptors. We analyzed the status of 10 different microsatellite loci (mono- and dinucleotide repeats). In this study, microsatellite size patterns were compared in 88 paired breast-cancer/peripheral-blood DNA samples. Fluorescent polymerase chain reaction (PCR) for typing microsatellites coupled with DNA fragment analysis in an automated DNA sequencer was applied. MSI in at least two microsatellite markers was observed in 6 out of 88 (7%) of the cases, all belonging to Stage II or III. These MSI data were analyzed using a range of clinicopathological parameters; no correlation between MSI and histopathological characteristics were found. A significant correlation was observed between MSI and negative expression of both estrogen and progesterone receptors (P<0.02), indicating a possible relationship between specific genetic changes at these microsatellite regions and hormonal deregulation in the progression of breast cancer.

Adult↗