The Rare and Atypical Diabetes Network (RADIANT) Study: Design and Early Results

OBJECTIVE

The Rare and Atypical Diabetes Network (RADIANT) will perform a study of individuals and, if deemed informative, a study of their family members with uncharacterized forms of diabetes.

RESEARCH DESIGN AND METHODS

The protocol includes genomic (whole-genome [WGS], RNA, and mitochondrial sequencing), phenotypic (vital signs, biometric measurements, questionnaires, and photography), metabolomics, and metabolic assessments.

RESULTS

Among 122 with WGS results of 878 enrolled individuals, a likely pathogenic variant in a known diabetes monogenic gene was found in 3 (2.5%), and six new monogenic variants have been identified in the SMAD5, PTPMT1, INS, NFKB1, IGF1R, and PAX6 genes. Frequent phenotypic clusters are lean type 2 diabetes, autoantibody-negative and insulin-deficient diabetes, lipodystrophic diabetes, and new forms of possible monogenic or oligogenic diabetes.

CONCLUSIONS

The analyses will lead to improved means of atypical diabetes identification. Genetic sequencing can identify new variants, and metabolomics and transcriptomics analysis can identify novel mechanisms and biomarkers for atypical disease.

Development of a molecular test of Paget's disease of bone

Depending on populations, 15 to 40% of patients have a familial form of Paget's disease of bone (PDB), which is transmitted in an autosomal-dominant mode of inheritance with incomplete penetrance. To date, only SQSTM1 gene mutations have been linked to the disease. Several single nucleotide polymorphisms (SNPs) have been associated with PDB in patient non-carriers of SQSTM1 mutations, but they have minor size effects. The current clinical practice guidelines still recommend to measure total serum alkaline phosphatase (sALP) for PDB screening. However, genetic or bone biomarkers alone may lack sensitivity to detect PDB. Thus, the objective of this study was to develop a molecular test of PDB, combining genetic and bone biomarkers, in order to detect PDB, which is frequently asymptomatic. We genotyped 35 SNPs previously associated with PDB in 305 patients, and 292 healthy controls. In addition, serum levels of 14 bone biomarkers were assayed in 51 patients and 151 healthy controls. Bivariate and multivariate logistic regression models with adjustment for age and sex were fitted to search for a combination of SNPs and/or bone biomarkers that could best detect PDB in patient non-carriers of SQSTM1 mutations. First, a combination of five genetic markers gave rise to the highest area under the ROC curve (AUC) with 95% confidence interval [95% CI] of 0.731 [0.688; 0.773], which allowed us to detect 81.5% of patients with PDB. Second, a combination of two bone biomarkers had an AUC of 0.822 [0.726; 0.918], and was present in 81.5% of patients with PDB. Then, the combination of the five genetic markers and the two bone biomarkers increased the AUC up to 0.892 [0.833; 0.951], and detected 88.5% of patients with PDB. These results suggested that an algorithm integrating first a screen for SQSTM1 gene mutations, followed by either a genetic markers combination or a combined genetic and biochemical markers test in patients non-carrier of any SQSTM1 mutation, may detect the PDB phenotype better than biomarkers already available in the clinical practice.

Detection of SQSTM1/P392L post-zygotic mutations in Paget's disease of bone

Paget’s disease of bone (PDB) is transmitted, in one-third of cases, in an autosomal dominant mode of inheritance with incomplete penetrance. The SQSTM1/P392L germinal mutation is the most common mutation associated with PDB. Given the focal nature of PDB, one team of investigators showed that SQSTM1/P392L somatic mutations could occur in pagetic bone lesions in the absence of germinal mutations detectable in the peripheral blood. The objectives of this study were to develop a reliable method to detect SQSTM1/P392L post-zygotic mutations, by optimizing a polymerase chain reaction (PCR)-clamping method reported to be effective in detecting post-zygotic mutations in peripheral blood from patients with fibrous dysplasia; and to evaluate the frequency of this post-zygotic mutation in PDB patients. We used a locked nucleic acid (LNA) specifically designed for the SQSTM1/P392L mutation, which blocks the wild-type allele amplification during the PCR. DNA from 376 pagetic patients and 297 controls, all without any SQSTM1/P392L germinal mutation, was analyzed. We found that 4.8 % of PDB patients and 1.4 % of controls were carriers of this post-zygotic mutation [p = 0.013, OR 3.68 (1.23; 11.00)]. PDB patient carriers of a post-zygotic mutation had a lower number of affected bones and Renier’s index than patients carrying a germinal mutation, suggesting a lower disease extension. We also demonstrated that this post-zygotic mutation was restricted to the monocytic lineage. These results confirmed that LNA PCR clamping is effective for the detection of SQSTM1/P392L post-zygotic mutations, which may occur in patients with PDB.

Genetic association study of Dickkopf-1 and sclerostin genes with paget disease of bone

Increased expression of DKK1 gene was reported in pagetic osteoblasts and stromal cells, and increased serum levels of DKK1 and SOST proteins were reported in patients with Paget disease of bone (PDB). This study aimed at identifying rare genetic variants of the DKK1 and SOST genes and at testing for genetic association with PDB in the French-Canadian population. Exons, promoters, and exon-intron junctions of these genes were sequenced in patients with PDB and healthy controls. An association study of Tag SNPs of both genes was also performed in 239 pagetic patients and 297 healthy individuals. Three rare variants were identified in this study, all located in the DKK1 gene: one variant in the second exon leading to alteration in a highly conserved amino acid (p.R120L), one in the 5'-untranslated region (-50 C/A), and one in a splice site of intron 1 (IVS1 184 T/C), although none of these rare variants were associated with PDB. A genetic association of a Tag SNP of the DKK1 gene was found: the G allele of rs1569198 was significantly decreased in patients in comparison to controls (42 vs. 49 %, uncorrected P = 0.03, OR = 0.77, 95 % CI 0.61-0.98). In conclusion, this study identified three rare genetic variants in DKK1 in the French-Canadian population. In addition, a weak genetic association of a common variant of DKK1, rs1569198, which is located on a predicted new acceptor site for splicing of this gene, was observed in PDB, whereas no rare variant or genetic association was found in the SOST gene.

Genetic association study of UCMA/GRP and OPTN genes (PDB6 locus) with Paget's disease of bone

We performed a genetic association study of rare variants and single nucleotide polymorphisms (SNPs) of UCMA/GRP and OPTN genes, in French-Canadian patients with Paget's disease of bone (PDB) and in healthy controls from the same population. We reproduced the variant found in the UCMA/GRP basal promoter and tested its functionality using in vitro transient transfection assays. Interestingly, this SNP rs17152980 appears to affect the transcription level of UCMA/GRP. In addition, we have identified five rare genetic variants in UCMA/GRP gene, four of them being population-specific, although none were found to be associated with PDB. Six Tag SNPs of UCMA/GRP gene were associated with PDB, particularly the SNP rs17152980 (uncorrected P=3.8 × 10(-3)), although not significant after Bonferroni's correction. More importantly, we replicated the strong and statistically significant genetic association of two SNPs of the OPTN gene, the rs1561570 (uncorrected P=5.7 × 10(-7)) and the rs2095388 (uncorrected P=4.9 × 10(-3)), with PDB. In addition, we identified a very rare variant found to be located close to the basal promoter of the OPTN gene, at -232bp from its distal transcription start site. Furthermore, depending on the type of allele present (G or A), the binding of several important nuclear factors such as the vitamin D or the retinoic acid receptors is predicted to be altered at this position, suggesting a significant effect in the regulation of transcription of the OPTN gene. In conclusion, we identified a functional SNP located in the basal promoter of the UCMA/GRP gene which provided a weak genetic association with PDB. In addition, we replicated the strong genetic association of two already known SNPs of the OPTN gene, with PDB in a founder effect population. We also identified a very rare variant in the promoter of OPTN, and through bioinformatic analysis, identified putative transcription factor binding sites likely to affect OPTN gene transcription.

Adipose Tissue Transcriptome by Serial Analysis of Gene Expression

OBJECTIVE

To describe the genomic expression profile or transcriptome of adipose tissue using the serial analysis of gene expression method.

RESEARCH METHODS AND PROCEDURES

The serial analysis of gene expression strategy is based on isolation of short sequences (tags), which usually correspond to unique transcripts, and on their concatenation into long DNA molecules, which are then cloned and sequenced. Experiments were performed with mRNA from retroperitoneal adipose tissue of male C57BL6 mice.

RESULTS

We isolated 45,996 tags corresponding to more than 17,000 different genes. Eighty-eight genes were expressed at more than 0.1% of the total population and represented 26% of the mRNA population identified. The most expressed genes were: carbonic anhydrase 3 (1.97%), cytochrome c oxidase (COX) 1 (1.47%), COX2 (1.25%), diazepam binding inhibitor (1.04%), a novel transcript (0.87%), COX3 (0.55%), fatty acid-binding protein 4 (0.55%), and NADH dehydrogenase 4 (0.52%). Other genes known to be expressed in adipose tissue, such as uncoupling protein 2, angiotensinogen, adipsin, and insulin-like growth factor 1, were found at a lower level. Several tags corresponding to novel transcripts were also found.

DISCUSSION

To our knowledge, the present results provide for the first time a quantitative description of the transcriptome in adipose tissue.

Novel SQSTM1 mutations in patients with Paget's disease of bone in an unrelated multiethnic American population

More than 20 mutations of the Sequestosome 1 (SQSTM1) gene have been reported in patients of European descent affected by Paget's disease of bone (PDB). In this investigation, a systematic screening for SQSTM1 mutations was conducted in consecutively evaluated unrelated patients with phenotypical PDB living in the New York City area (NY, United States). Seventy unrelated PDB patients with a multiethnic background, mostly of Jewish, Italian American, and Western European ancestries, were recruited. Sequencing of exons 7 and 8 was performed on DNA samples isolated from peripheral blood. Seven patients (10%) had SQSTM1 mutations, of which three had a family history of PDB. Four patients carried the C1215T (P392L) mutation, and three patients carried novel SQSTM1 missense mutations: T1085A (S349T), C1209T (A390V), and T1290A (L417Q) mutations. All PDB patients with SQSTM1 mutations had polyostotic involvement, and the mean number of affected bones was significantly higher in pagetic patient carriers of a SQSTM1 mutation when compared to non-mutated PDB patients (4.0 vs. 2.0, respectively; P = 0.003). Haplotype analysis in patient carriers of the P392L mutation revealed that all P392L mutations were carried by haplotype 2. The SQSTM1 mutation rate in unrelated American patients described in the present study was similar to that reported in European populations.

Contributions of the measles virus nucleocapsid gene and the SQSTM1/p62(P392L) mutation to Paget's disease

Paget's disease (PD) is characterized by abnormal osteoclasts (OCL) that secrete high IL-6 levels and induce exuberant bone formation. Because measles virus nucleocapsid gene (MVNP) and the p62(P392L) mutation are implicated in PD, marrows from 12 PD patients harboring p62(P392L) and eight normals were tested for MVNP expression and pagetic OCL formation. Eight out of twelve patients expressed MVNP and formed pagetic OCL in vitro, which were inhibited by antisense-MVNP. Four out of twelve patients lacked MVNP and formed normal OCL that were hyperresponsive to RANKL but unaffected by antisense-MVNP. Similarly, mice expressing only p62(P394L) formed normal OCL, while mice expressing MVNP in OCL, with or without p62(P394L), developed pagetic OCL and expressed high IL-6 levels dependent on p38MAPK activation. IL-6 deficiency in MVNP mice abrogated pagetic OCL development in vitro. Mice coexpressing MVNP and p62(P394L) developed dramatic Paget's-like bone lesions. These results suggest that p62(P394L) and IL-6 induction by MVNP play key roles in PD.

Gene expression profile in osteoclasts from patients with Paget's disease of bone

Paget's disease of bone (PDB) is a common metabolic bone disorder with a significant genetic component. To date, only one gene associated with PDB has been identified, the p62-Sequestosome1 gene (SQSTM1), and more than 20 mutations of this gene have been reported in PDB, the most common being the P392L substitution. In order to search for differentially expressed genes in PDB, we investigated the relative gene expression profile of candidate genes in osteoclast (OCL) cultures from 12 PDB patients and six unmatched healthy controls with known genetic status regarding p62, including healthy carriers of the P392L mutation. We selected 48 OCL-expressed candidate genes that may be involved in relevant pathways of PDB pathogenesis, such as OCL signaling, survival, bone resorption activity, or adhesion. In OCL cultures derived from peripheral blood mononuclear cells, total RNA extraction was performed, followed by real-time PCR experiments. Relative quantification analysis utilized the qBase method where relative expression levels were normalized with respect to a set of reference primer pairs for three housekeeping genes. When compared to non-mutated healthy controls, OCL cultures from PDB patients displayed a significant down-regulation in genes involved in apoptosis (CASP3 and TNFRSF10A), in cell signaling (TNFRSF11A), in the OCL bone resorbing function (ACP5 and CTSK) and in the gene coding for Tau protein (MAPT) (all comparisons, p<0.0001). Comparison of relative gene expression in PDB patients with P392L mutation versus PDB patients without SQSTM1 mutation did not provide significant differential gene expression. However, we observed a non-significant decrease in the expression of several genes such as IL6ST, HIF1A, OSTM1, TNFRSF-10B and -10D, PDK1, MAPT and CASP3 in healthy carriers of the P392L mutation. These results provide important information about the mis-regulated activities of pagetic OCL, and highlight the role of altered apoptosis pathways in these cells. They also suggest that the SQSTM1 P392L mutation plays a role in PDB pathogenesis, even at early preclinical stages in healthy carriers of the P392L mutation.

Fine temporal analysis of DHT transcriptional modulation of the ATM/Gadd45g signaling pathways in the mouse uterus

In rodents, the uterus of a mature female undergoes changes during the uterine cycle, under the control of steroid hormones. 5alpha-Dihydrotestosterone (DHT) is recognized to play an important role in the regulation of androgen action in normal endometrium. Using microarray technology, a screening analysis of genes responding to DHT in the uterus of ovariectomized mice, has allowed us to highlight multiple genes of the ATM/Gadd45g pathway that are modulated following exposure to DHT. Two phases of regulation were identified. In the early phase, the expression of genes involved in the G2/M arrest is rapidly increased, followed by the repression of genes of the G1/S checkpoint, and by the induction of transcriptional regulators. Later, i.e. from 12 to 24 hr, genes involved in G2/M transition, cytoarchitectural and lipid-related genes are stimulated by DHT while immunity-related genes appear to be differentially regulated by the hormone. These results show that a physiological dose of DHT induces the transcription of genes promoting the cell cycle progression in mice. Profile determination of temporal uterine gene expression at the transcriptional level enables us to suggest that the DHT modulation of genes involved in ATM/Gadd45g signaling in an ATM- or p53-independent manner, could play an important role in the cyclical changes of uterine cells in the mouse uterus.

The p62 P392L mutation linked to Paget's disease induces activation of human osteoclasts

Mutations of the gene encoding p62/SQSTM1 have been described in Paget's disease of bone (PDB), identifying p62 as an important player in osteoclast signaling. We investigated the phenotype of osteoclasts differentiated from peripheral blood monocytes obtained from healthy donors or PDB patients, all genotyped for the presence of a mutation in the p62 ubiquitin-associated domain. The cohort included PDB patients carrying or not the p62 P392L mutation and healthy donors carrying or not this mutation. Osteoclasts from PDB patients were more numerous, contained more nuclei, were more resistant to apoptosis, and had a greater ability to resorb bone than their normal counterparts, regardless of whether the p62 mutation was present or not. A strong increase in p62 expression was observed in PDB osteoclasts. The presence of the p62(P392L) gene in cells from healthy carriers conferred a unique, intermediate osteoclast phenotype. In addition, we report that two survival-promoting kinases, protein kinase Czeta and phosphoinositide-dependent protein kinase 1, were associated with p62 in response to receptor activator of NF-kappaB ligand (RANKL) stimulation in controls and before RANKL was added in PDB osteoclasts. In transfected osteoclasts derived from cord blood monocytes, the p62 P392L mutation contributed to increased activation of kinases protein kinase Czeta/lambda and phosphoinositide-dependent protein kinase 1, along with basal activation of NF-kappaB, independently of RANKL stimulation. These findings clearly indicate that the overexpression of p62 in PDB patients induces important shifts in the pathways activated by RANKL and up-regulates osteoclast functions. Moreover, the most-commonly reported p62 mutation, P392L, certainly contributes to the overactive state of osteoclasts in PDB.

Pangenomic changes induced by DHEA in the skin of postmenopausal women

The objective of this study was to explore, for the first time, the changes in the pangenomic profile induced in human skin in women treated with dehydroepiandrosterone (DHEA) applied locally. Sixty postmenopausal women participated in this phase II prospective, randomized, double-blind and placebo-controlled study. Women were randomized to the twice daily local application of 0% (placebo), 0.3%, 1% or 2% DHEA cream. Changes in the pangenomic expression profile were studied using Affymetrix Genechips. Significant changes (p<0.05) in sixty-six DHEA-responsive probe sets corresponding to 52 well-characterized genes and 9 unknown gene sequences were identified. A dose-dependent increase in the expression of several members of the collagen family was observed, namely COL1, COL3 and COL5 as well as the concomitant modulation of SPARC, a gene required for the normal deposition and maturation of collagen fibrils in the dermis. Several genes involved in the proliferation and differentiation of keratinocytes were also modulated. In addition, topical DHEA reduced the expression of genes associated with the terminal differentiation and cornification of keratinocytes. Our results strongly suggest the possibility that DHEA could exert an anti-aging effect in the skin through stimulation of collagen biosynthesis, improved structural organization of the dermis while modulating keratinocyte metabolism.

La statistique agrégée des patronymes du Saguenay et de Charlevoix comme indicateurs de la structure de la population aux XIXe et XXe siècles

L’analyse de la statistique des patronymes du Saguenay et de Charlevoix depuis le XIXe siècle suggère que les populations de ces deux régions sont extrêmement similaires, l’une ayant été créée à partir de l’autre. S’agissant plus particulièrement du Saguenay, les structures du bassin patronymique y sont demeurées relativement stables entre 1842 et 1971. Les auteurs pensent que, à titre préliminaire, la statistique des noms de famille peut être un indicateur utile non seulement de la dynamique d’une population, mais aussi de l’ensemble de son bassin génétique. Elle semble cependant mal refléter la diffusion d’un gène en particulier : on ne trouve pas ici de corrélation entre le fait de porter tel nom et la probabilité de porter tel ou tel gène délétère.

Temporal analysis of E2 transcriptional induction of PTP and MKP and downregulation of IGF-I pathway key components in the mouse uterus

17beta-Estradiol (E2) is well known to be associated with uterine cancer, endometriosis, and leiomyomas. Although insulin-like growth factor I (IGF-I) has been identified as a mediator of the uterotrophic effect of E2 in several studies, this mechanism is still not well understood. In the present study, identification of the genes modulated by a physiological dose of E2, in the uterus, has been done in ovariectomized mice using Affymetrix microarrays. The E2-induced genomic profile shows that multiple genes belonging to the IGF-I pathway are affected after exposure to E2. Two phases of regulation could be identified. First, from 0 to 6 h, the expression of genes involved in the cell cycle, growth factors, protein tyrosine phosphatases, and MAPK phosphatases is quickly upregulated by E2, while IGF-I receptor and several genes of the MAPK and phosphatidylinositol 3-kinase pathways are downregulated. Later, i.e., from 6 to 24 h, transporters and peptidases/proteases are stimulated, whereas defense-related genes are differentially regulated by E2. Finally, cytoarchitectural genes are modulated later. The present data show that a physiological dose of E2 induces, within 24 h, a series of transcriptional events that promote the uterotrophic effect. Among these, the E2-mediated activation of the IGF-I pathway seems to play a pivotal role in the uterotrophic effect. Furthermore, the protein tyrosine phosphatases and MAPK phosphatases are likely to modulate the estrogenic uterotrophic action by targeting, at different steps, the IGF-I pathway.

Sequestosome 1: mutation frequencies, haplotypes, and phenotypes in familial Paget's disease of bone

Mutations of the SQSTM1/p62 gene are commonly observed in PDB. Screening an updated sample from Quebec and using previously published data from other populations, we compared frequency estimates for SQSTM1/p62 mutations and haplotype distribution. The P392L mutation was the most prevalent, embedded in two different haplotypes, possibly shared by other populations. We also examined the phenotype and penetrance of P392L.

INTRODUCTION

There is accumulating evidence that supports a contribution of genetic factors in the etiology of Paget's disease of bone (PDB), and several genetic loci have been suggested for the disorder. The sequestosome1/p62 (SQSTM1/p62) gene was the first gene identified to have a role in PDB, with 14 mutations reported to date.

MATERIAL AND METHODS

To evaluate the importance of the SQSTM1/p62 mutations in PDB, we recruited, sequenced, and genotyped a total of 123 carriers from 20 families in addition to 214 unrelated PDB patients. We compared the frequency of SQSTM1/p62 mutations in familial and unrelated cases among different populations. Finally, we examined the phenotypic expression and penetrance of the P392L mutation in the Quebecois families.

RESULTS AND CONCLUSIONS

The 14 mutations reported in SQSTM1/p62 all affect the ubiquitin-associated domain of the protein. The P392L mutation is the most commonly observed mutation in PDB patients and was consistently found in unrelated and familial PDB cases in the populations tested. Analysis of adjacent polymorphisms suggests that P392L is associated with two different haplotypes in the Quebecois patients, similar to what has been observed in European populations. In Quebec, both haplotypes had similar frequencies in unrelated P392L carriers, whereas one haplotype was predominant in the other populations studied. These data suggest that these two haplotypes, possibly introduced by European founders in the Quebecois population, were equally distributed in the succeeding generations. Finally, the P392L mutation is transmitted as an autosomal dominant trait in the Quebecois families, with a high but incomplete penetrance peaking after age 60. The large phenotypic variability and similarity between unrelated and familial cases, respectively, remain unexplained and require further research.

Dehydroepiandrosterone (DHEA) is an anabolic steroid like dihydrotestosterone (DHT), the most potent natural androgen, and tetrahydrogestrinone (THG)

We have recently taken advantage of the unique power of DNA microarrays to compare the genomic expression profile of tetrahydrogestrinone (THG) with that of dihydrotestosterone (DHT), the most potent natural androgen, thus clearly demonstrating that THG is an anabolic steroid. In 2004, the U.S. Controlled Substances Act has been modified to include androstenedione (4-dione) as an anabolic steroid. However, despite the common knowledge that dehydroepiandrosterone (DHEA) is the precursor of testosterone, DHEA has been excluded from the list of anabolic steroids. We thus used the same DNA microarray technology to analyze the expression profile of practically all the 30,000 genes of the mouse genome modulated by DHEA and DHT in classical androgen-sensitive tissues. Daily subcutaneous injections of DHT (0.1mg) or DHEA (3mg) for 1 month in gonadectomized C57BL6/129 SV mice increased ventral prostate, dorsal prostate, seminal vesicle and preputial gland weight (p<0.01 for all tissues). As early as 24h after single injection of the two steroids, 878, 2681 and 14 probe sets were commonly stimulated or inhibited (p<0.01, change> or =30%), in the prostate (ventral+dorsal), seminal vesicles and preputial glands, respectively, compared to tissues from gonadectomized control animals. After 7 days of daily treatment with DHEA and DHT, 629, 919 and 562 probe sets were commonly modulated in the same tissues while after 27 days of treatment, 1195, 5127 and 2883 probe sets were modulated, respectively. In analogy with the data obtained with THG, the present microarray data provide an extremely precise and unquestionable genomic signature and proof of the androgenic/anabolic activity of DHEA. Such data add to the literature showing that DHEA is transformed into androgens in the human peripheral tissues as well as in laboratory animal species, including the monkey, thus exerting potent androgenic/anabolic activity. The present microarray approach to identify anabolic compounds is applicable to all potential androgenic/anabolic compounds.

A genome-wide scan points to a susceptibility locus for bipolar disorder on chromosome 12

Our previous results pointed to a putative gene for susceptibility to bipolar affective disorder located on the chromosomal region 12q23-q24 that segregated in the Saguenay-Lac-St-Jean population of Quebec. We report here results from a second genome-wide scan based on the analysis of 380 polymorphic microsatellite markers. For the purpose of this analysis, an additional 18 families were recruited from the Saguenay-Lac-St-Jean region and pooled to our previous sample to improve its statistical power, giving a total of 394 sampled individuals. This work confirms the presence of a susceptibility locus for affective disorder on chromosome 12q24 with parametric LOD score value of 3.35 at D12S378 when pedigrees were broken into nuclear families and analysed under a recessive segregation model. This result was supported by neighbouring markers and by a LOD score value of 5.05 at D12S378 under model-free analysis. Other regions of lower interest were indicated on chromosomes 2, 5, 7, 9, 10, 17 and 20.

Tetrahydrogestrinone induces a genomic signature typical of a potent anabolic steroid

Tetrahydrogestrinone (THG) is a recently identified compound having the greatest impact in the world of sports. In order to obtain a highly accurate and sensitive assessment of the potential anabolic/androgenic activity of THG, we have used microarrays to identify its effect on the expression of practically all the 30,000 genes in the mouse genome and compared it with the effect of dihydrotestosterone (DHT), the most potent natural androgen. Quite remarkably, we found that 671 of the genes modulated by THG in the mouse muscle levator ani are modulated in a similar fashion by DHT, while in the gastrocnemius muscle and prostate, 95 and 939 genes respectively, are modulated in common by the two steroids. On the other hand, THG is more potent than DHT in binding to the androgen receptor, while, under in vivo conditions, THG possesses 20% of the potency of DHT in stimulating prostate, seminal vesicle and levator ani muscle weight in the mouse. The present microarray data provide an extremely precise and unquestionable signature of the androgenic/anabolic activity of THG, an approach which should apply to the analysis of the activity of any anabolic steroid.

No evidence of maternal cell colonization in reverted liver nodules of tyrosinemia type I patients

BACKGROUND AND AIMS

Hereditary tyrosinemia type I (HTI) is a recessively inherited disease caused by a deficiency of fumarylacetoacetate hydrolase (FAH), the last enzyme of the tyrosine catabolic pathway. The mosaic pattern of FAH expression observed in the livers of >85% of studied patients was shown to result from the correction of the mutation in one of the FAH alleles. Bilateral cell trafficking can occur between mother and fetus and such an event could be responsible for the chimerism observed in some diseases. It also has been reported that the liver repopulation observed in a HTI murine model by serial transplantation of bone marrow-derived cells was caused by a fusion of these cells to host hepatocytes. These observations led us to test the possibility that the transfer of nucleated heterozygous maternal cells in the fetal circulation could be responsible for the mosaic liver expression of FAH in HTI patients.

METHODS

We used polymorphic markers of short cytosine-adenine DNA repeats to compare DNA from corrected liver sections of 4 HTI patients with DNA from their parents' blood.

RESULTS

Genotyping showed that only one maternal allele is present in DNA isolated from FAH-expressing liver nodules of each proband for at least 1 marker.

CONCLUSIONS

The corrected liver nodules in HTI patients are not of maternal origin and do not support cell trafficking and cell fusion as mechanisms of correction of the gene defect in hepatocytes of tyrosinemia patients.

Intracellular Sequestration of Hetero-oligomers Formed by Wild-Type and Glaucoma-Causing Myocilin Mutants

PURPOSE

To investigate mechanism(s) by which mutations in the olfactomedin domain of myocilin (MYOC), also known as the trabecular meshwork-induced glucocorticoid response (TIGR) gene, cause autosomal dominant open-angle glaucoma, the structure and properties of wild-type (WT) MYOC protein were examined, when expressed alone or simultaneously with the Q368X or K423E disease-associated polypeptides.

METHODS

Myocilin was analyzed in human aqueous humor and human trabecular meshwork (HTM) tissues. COS-7 and immortalized human trabecular meshwork (iHTM) cell lines were transfected with expression vectors encoding WT MYOC, mutated, and/or epitope-tagged cDNAs. MYOC proteins were characterized by double-epitope tagging procedures and/or Western blot analysis.

RESULTS

MYOC polypeptides formed highly similar oligomers in aqueous humor, HTM tissues, transfected COS-7, and iHTM cell lines. These complexes ranged in size from 116 kDa to more than 200 kDa. The smallest complex, approximately 116 kDa, resulted from dimerization between two MYOC monomers. Expression of a 150-kDa complex was strongest in aqueous humor. Cotransfections of the WT construct with either the Q368X or K423E cDNA produced MYOC(WT)/MYOC(mutant) heterodimers and higher molecular weight hetero-oligomeric complexes. WT homo-oligomeric complexes were secreted in the extracellular media of both cell lines whereas the Q368X and K423E mutant/mutant homomultimers and heteromeric WT/mutant oligomers remained sequestered intracellularly.

CONCLUSIONS

Formation of heteromeric WT/mutant complexes may provide a critical mechanism by which mutant myocilin polypeptides produce autosomal dominant open-angle glaucoma. The intracellular sequestration of abnormal WT/mutant complexes could lead to the malfunction of MYOC-expressing cells and to POAG potentially involving a dominant negative effect.

Effects of dihydrotestosterone on adipose tissue measured by serial analysis of gene expression

Intra-abdominal fat accumulation is related to several diseases, especially diabetes and heart disease. Molecular mechanisms associated with this independent risk factor are not well established. Through the serial analysis of gene expression (SAGE) strategy, we have studied the transcriptomic effects of castration and dihydrotestosterone (DHT) in retroperitoneal adipose tissue of C57BL6 male mice. Approximately 50,000 SAGE tags were isolated in intact and gonadectomized mice, as well as 3 and 24 h after DHT administration. Transcripts involved in energy metabolism, such as glyceraldehyde-3-phosphate dehydrogenase, malic enzyme supernatant, fatty acid synthase, lipoprotein lipase, hormone-sensitive lipase and monoglyceride lipase, were upregulated by DHT. Transcripts involved in adipogenesis, and cell cycle and cell shape organization, such as DDX5, C/EBPalpha, cyclin I, procollagen types I, III, IV, V and VI, SPARC and matrix metalloproteinase 2, were upregulated by DHT. Cell defense, division and signaling, protein expression and many novel transcripts were regulated by castration and DHT. The present results provide global genomic evidence for a stimulation of glycolysis, fatty acids and triacylglycerol production, lipolysis and cell shape reorganization, as well as cell proliferation and differentiation, by DHT. The novel transcripts regulated by DHT may contribute to identify new mechanisms involved in the action of sex hormones and their potential role in obesity.

Axenfeld-Rieger Anomaly

OBJECTIVE

To characterize DNA mutations in a pedigree of Axenfeld-Rieger anomaly (ARA) (Online Mendelian Inheritance of Man 601631), a clinically and genetically heterogeneous, autosomal dominantly inherited disorder associated with anterior chamber abnormalities and glaucoma.

DESIGN

Observational case-control and DNA linkage and screening studies.

PARTICIPANTS

Affected (10 cases) and unaffected (5 controls) members of a family with ARA.

METHODS

Clinical characteristics of ARA were documented by history or physical examination of symptomatic individuals. With their informed consent, a blood sample was collected from each of 10 affected and 5 unaffected family members. DNA was tested for linkage to the IRID1 locus at chromosome 6p25, a known locus for ARA/Rieger syndrome. A candidate gene previously mapped at this locus, FOXC1, was screened for mutations in cases and controls. Main Outcome Measure Linkage of the ARA phenotype at the 6p25 locus and mutation detected in FOXC1.

RESULTS

Direct sequencing of FOXC1 detected a new mutation, T272C, that segregated with the ARA phenotype in this family and was not detected in DNA from family members without ARA. This mutation, a T-->C transition, is predicted to result in a change of isoleucine to threonine (Ile9lThr) in a highly conserved location within the first helix of the forkhead domain.

CONCLUSION

Characterization of the FOXC1 mutation in family members with ARA furthers our understanding of the molecular origin of developmental glaucoma and other anterior segment disorders.

Transcriptome of mouse uterus by serial analysis of gene expression (SAGE): Comparison with skeletal muscle

The aim of this study was to identify the transcriptome of the normal mouse uterus by Serial Analysis of Gene Expression method. mRNA was extracted from the uterus and also from the gastrocnemius muscle of mice. Short sequences (tags), each one usually corresponding to a distinct transcript, were isolated and concatemerized into long DNA molecules which were cloned and sequenced. We detected 44,484 tags for the uterus and 42,518 tags for the muscle, representing 14,543 and 14,958 potential transcript species, respectively. Seventy-five and sixty-nine genes were expressed at more than 0.1%, thus corresponding to 37 and 34% of the mRNA population detected in the respective tissues. In both cases, the most highly expressed genes are especially involved in muscle contraction, energy metabolism, and protein synthesis. Compared to skeletal muscle, some differentially expressed genes in the uterus are likely to correspond to its specific reproductive functions. The majority of these genes remain to be characterized. More than 70% of the different tags detected in the uterus did not match any sequence in the public databases and can represent novel or poorly identified genes. This study is the first quantitative description of the transcriptome of the uterus.

Genome scan meta-analysis of schizophrenia and bipolar disorder, part III: Bipolar disorder

Genome scans of bipolar disorder (BPD) have not produced consistent evidence for linkage. The rank-based genome scan meta-analysis (GSMA) method was applied to 18 BPD genome scan data sets in an effort to identify regions with significant support for linkage in the combined data. The two primary analyses considered available linkage data for "very narrow" (i.e., BP-I and schizoaffective disorder-BP) and "narrow" (i.e., adding BP-II disorder) disease models, with the ranks weighted for sample size. A "broad" model (i.e., adding recurrent major depression) and unweighted analyses were also performed. No region achieved genomewide statistical significance by several simulation-based criteria. The most significant P values (<.01) were observed on chromosomes 9p22.3-21.1 (very narrow), 10q11.21-22.1 (very narrow), and 14q24.1-32.12 (narrow). Nominally significant P values were observed in adjacent bins on chromosomes 9p and 18p-q, across all three disease models on chromosomes 14q and 18p-q, and across two models on chromosome 8q. Relatively few BPD pedigrees have been studied under narrow disease models relative to the schizophrenia GSMA data set, which produced more significant results. There was no overlap of the highest-ranked regions for the two disorders. The present results for the very narrow model are promising but suggest that more and larger data sets are needed. Alternatively, linkage might be detected in certain populations or subsets of pedigrees. The narrow and broad data sets had considerable power, according to simulation studies, but did not produce more highly significant evidence for linkage. We note that meta-analysis can sometimes provide support for linkage but cannot disprove linkage in any candidate region.

Genetic heterogeneity in a very large bipolar affective disorder pedigree from Quebec

We previously reported a genome-wide scan for bipolar affective disorder based on a multigenerational family sampled from a relatively homogeneous population derived from founding families that migrated to an isolated area of Quebec from the early 1830s onwards. For the genome scan, the pedigree was split into five branches to facilitate calculation and a second family was added to more specifically analyze chromosome 12 results. In the present study, we reanalyzed the undivided pedigree after genealogical links were reconstructed over ten generations to investigate a founder effect using an algorithm in the SIMWALK2 package. Our results do not lend support to the presence of a common haplotype shared among affected individuals.

Support for the presence of bipolar disorder susceptibility loci on chromosome 5: heterogeneity in a homogeneous population in Quebec

A very large pedigree derived from the Saguenay-Lac-St-Jean region of Quebec contains a branch where a distal chromosome 5q haplotype seems to cosegregate with bipolar affective disorder. The authors used a diagnosis model where Bipolar Types I and II and schizoaffective disorder bipolar type were considered as affected, while single or recurrent episode major depression was classified as unknown and all the others diagnoses as unaffected. Model-free two-point LOD score values of 3.41 and 2.21 were observed at D5S432 in the 5p region with sib_ibd and sib_phase from the ASPEX package, but simulation studies did not permit the conclusion of a significant linkage because associated empirical P values were equal to .0026 and .0037. A parametric LOD score value of 2.15 was obtained at locus D5S412 in the distal chromosome 5q area. In order to investigate heterogeneity in the single multigenerational family, the pedigree was divided into five branches. Our simulation study suggested that the five branches of the Saguenay-Lac-St-Jean bipolar pedigree had low power to detect linkage under intrapedigree heterogeneity in this region.

Founder TIGR/myocilin mutations for glaucoma in the Québec population

Primary open-angle glaucoma (POAG) is a complex disorder characterized by a progressive and treatable degeneration of the optic nerve. TIGR/myocilin (MYOC) gene mutations are found in approximately 4% of all POAG patients. Populations with frequent founder effects, such as the French-Canadians, offer unique advantages to implement genetic testing for the disorder. To assess molecular diagnosis for POAG in this population, we determined the prevalence of TIGR/MYOC mutations in 384 unrelated glaucoma patients, 38 ocular hypertensive subjects and 18 affected families (180 patients). We further analyzed the clinical features associated with these variations. Nine coding sequence variants were defined as mutations causing mostly, but not exclusively, POAG. Four families segregated distinct mutations (Gly367Arg, Gln368Stop, Lys423Glu and Pro481Leu), while 14 unrelated glaucoma patients harbored six known mutations (Thr293Lys, Glu352Lys, Gly367Arg, Gln368Stop, Lys423Glu and Ala445Val) and two novel (Ala427Thr and Arg126Trp). The frequencies of these mutations were respectively 3.8% and 22.2% in the unrelated and family studies. The Gly367Arg and Lys423Glu variants caused the earliest ages at onset. When achievable, assessment of relatives of unrelated mutation carriers showed the Arg126Trp and Gly367Arg to be familial. Characteristic allele signatures, indicative of specific founder effects, were observed for five of the six mutations conveyed by at least two patients. Recombination probability estimates suggested that the French-Canadian population had most probably inherited these six mutations from 7-10 Québec settlers. Our data demonstrated that genetic screening for TIGR/MYOC mutations should be offered to glaucoma families and to close relatives of unrelated patients aware of a family history for the disorder.

Osteogenesis imperfecta type VII maps to the short arm of chromosome 3

We have identified a novel form of autosomal recessive osteogenesis imperfecta (OI) in a small First Nations community from northern Quebec. Mutation screening of the COL1A1/COL1A2 genes revealed no detectable mutations, and type I collagen protein analyses were also normal. By linkage analysis, we mapped this unique autosomal recessive variant of osteogenesis imperfecta to chromosome 3p22-24.1. Based on the assumption of a founder effect, genome-wide screening was performed on a DNA sample pooled from seven affected individuals. Familial as well as historical recombinations identified within an extended haplotype of 19 markers localized the disease between markers D3S2324 and D3S1561, separated by <5 cM. Based on chromosomal localization to 3p22-24.1, the transforming growth factor-beta receptor 2 gene and the parathyroid hormone/parathyroid hormone-related peptide receptor were tested, but were excluded as being associated with the phenotype. This study excludes type I collagen mutations in the pathogenesis of the disease and assigns this form of OI to a locus other than the ones containing the type I collagen genes.

Recurrent mutation of the gene encoding sequestosome 1 (SQSTM1/p62) in Paget disease of bone

Paget disease of bone (PDB) is a common disorder characterized by focal and disorganized increases of bone turnover. Genetic factors are important in the pathogenesis of PDB. We and others recently mapped the third locus associated with the disorder, PDB3, at 5q35-qter. In the present study, by use of 24 French Canadian families and 112 unrelated subjects with PDB, the PDB3 locus was confined to approximately 300 kb. Within this interval, two disease-related haplotype signatures were observed in 11 families and 18 unrelated patients. This region encoded the ubiquitin-binding protein sequestosome 1 (SQSTM1/p62), which is a candidate gene for PDB because of its association with the NF-kappaB pathway. Screening SQSTM1/p62 for mutations led to the identification of a recurrent nonconservative change (P392L) flanking the ubiquitin-associated domain (UBA) (position 394-440) of the protein that was not present in 291 control individuals. Our data demonstrate that two independent mutational events at the same position in SQSTM1/p62 caused PDB in a high proportion of French Canadian patients.

Criterion validity study of lumbar goniometers BROM II and EDI-320 for range of motion of lumbar flexion of low back pain patients

PURPOSE

The purpose was to estimate the criterion validity of the Back Range of Motion (BROM II) and Electronic Digital Inclinometer (EDI-320) devices. METHODS. This study compared the range of motion measurements of low back pain (LBP) patients taken with the BROM II and EDI-320 with measurements using the double inclinometer (DI) method as the gold standard. Forty subjects with LBP volunteered for the study. The subjects were asked to do three forward flexion movements. A measurement was taken with each of the three different devices for each movement.

RESULTS

The BROM II demonstrated good linear relationship (Pearson r = 0.78; 95% CI: 0.78-0.94) and the EDI-320 very good linear relationship (Pearson r = 0.88; 95% CI: 0.62-0.89) with the gold standard, the DI.

CONCLUSIONS

The Pearson correlation value indicates good validity of the EDI-320 in our sample of LBP patients. Although a good correlation was established for the BROM II, the significant difference of the mean ROM reported for this instrument compared to the gold standard data suggests that the BROM II actually measures ROM differently. Our results suggest that the EDI 320 is clinically useful in providing objective and valid data for outcome measures in a population with LBP. More research is needed on the BROM II before we can make final conclusion on its use in clinical settings as an outcome measure.

A radiation hybrid transcript map of the mouse genome

Expressed-sequence tag (EST) maps are an adjunct to sequence-based analytical methods of gene detection and localization for those species for which such data are available, and provide anchors for high-density homology and orthology mapping in species for which large-scale sequencing has yet to be done. Species for which radiation hybrid-based transcript maps have been established include human, rat, mouse, dog, cat and zebrafish. We have established a comprehensive first-generation-placement radiation hybrid map of the mouse consisting of 5,904 mapped markers (3,993 ESTs and 1,911 sequence-tagged sites (STSs)). The mapped ESTs, which often originate from small-EST clusters, are enriched for genes expressed during early mouse embryogenesis and are probably different from those localized in humans. We have confirmed by in situ hybridization that even singleton ESTs, which are usually not retained for mapping studies, may represent bona fide transcribed sequences. Our studies on mouse chromosomes 12 and 14 orthologous to human chromosome 14 show the power of our radiation hybrid map as a predictive tool for orthology mapping in humans.

Paget disease of bone: mapping of two loci at 5q35-qter and 5q31

Paget disease of bone is characterized by focal increases of the bone-remodeling process. It is the second most common metabolic bone disease after osteoporosis. Genetic factors play a major role in the etiology of Paget disease of bone, and two loci have been mapped for the disorder: PDB1 and PDB2. The gene(s) causing the typical form of the disorder remains to be characterized. To decipher the molecular basis of Paget disease of bone, we performed genetic linkage analysis in 24 large French Canadian families (479 individuals) in which the disorder was segregating as an autosomal dominant trait. After exclusion of PDB2, a genomewide scan was performed on the three most informative family nuclei. LOD scores >1.0 were observed at seven locations. The 24 families were then used to detect strong evidence for linkage to chromosome 5q35-qter. Under heterogeneity, a maximum LOD score of 8.58 was obtained at D5S2073, at straight theta= .1. The same characteristic haplotype was carried by all patients in eight families, suggesting a founder effect. A recombination event in a key family confined the disease region within a 6-cM interval between D5S469 and the telomere. The 16 other families, with very low conditional probability of linkage to 5q35-qter, were further used, to map a second locus at 5q31. Under heterogeneity, a maximum LOD score of 3.70 was detected at D5S500 with straight theta=.00. Recombination events refined the 5q31 region within 12.2 cM, between D5S642 and D5S1972. These observations demonstrate the mapping of two novel loci for Paget disease of bone and provide further evidence for genetic heterogeneity of this highly prevalent disorder. It is proposed that the 5q35-qter and 5q31 loci be named "PDB3" and "PDB4," respectively.

Isolated four-chamber working swine heart model

BACKGROUND

Isolated heart models separate cardiac characteristics from systemic characteristics with subsequent findings used in cardiac research, including responses to pharmacologic, mechanical, and electrical components. The model objective was to develop the ability to represent in situ physiologic cardiac function ex vivo.

METHODS

Swine hearts were chosen over rat or guinea pig models due to their notably greater anatomical and physiologic similarities to humans. An in vitro apparatus was designed to work all four chambers under simulated in situ physiologic conditions. Using standard cardiac surgical techniques, 12 porcine hearts (mean weight 331 +/- 18 g) were explanted into the apparatus. Preload and afterload resistances simulated in situ input and output physiologic conditions. Hemodynamic characterizations, including cardiac output, max +/- dP/dt, and heart rate, were used to determine in situ function leading to explantation (prethoracic operation, postmedial sternotomy, and postperidectomy) and during in vitro function (t = 0, 60, 120, and 240 minutes).

RESULTS

In vitro performance decayed with time, with statistical differences from base line (t = 0) function at t = 240 minutes (p > 0.05).

CONCLUSIONS

An isolation and in vitro explantation protocol has been improved to aid in the study of isolated cardiac responses, and to determine cardiac hemodynamic function during open chest operation, transplantation, and in vitro reanimation with a crystalloid perfusate. The resulting model offers similar working physiologic function, with real-time imaging capabilities. The resulting model is advantageous in representing human cardiac function with regard to anatomic and physiologic functions, and can account for atrial and ventricular interactions.

Evidence for association and linkage between atopy, airway hyper-responsiveness, and the beta subunit Glu237Gly variant of the high-affinity receptor for immunoglobulin E in the French-Canadian population

Following detection of linkage between atopy and chromosome 11q13 markers, association between this disorder and variants of the beta subunit of the high-affinity receptor for immunoglobulin E (FcepsilonRI-beta, a candidate gene for asthma-related conditions co-localizing within the same region) was reported in Australian, British and Japanese populations. Investigations in several other ethnic groups failed to replicate these observations. Due to the complexity of defining intermediate phenotypes related to asthma, detection of such associations may have been hampered by clinical misclassifications. To assess whether the FcepsilonRI-beta gene was involved in atopy and/or airway hyperresponsiveness (AHR) in the French-Canadian population, we conducted a case-control study in 200 subjects using strict criteria for asthma and related conditions. The Ile181Leu and Glu237Gly FcepsilonRI-beta sequence variants were tested exploiting two amplification refractory mutation systems. No association was detected between atopy or AHR and the Ile181Leu FcepsilonRI-beta variant. However, a strong association was observed between atopy and the Glu237Gly FcepsilonRI-beta variant (odds ratio=12.25). Four large Eastern Québec families (n=106 subjects) were also recruited to perform a genetic linkage study. We observed suggestive evidence of linkage between atopy and the Glu237Gly FcepsilonRI-beta variant (Zmax=2.30). This study is the first to detect the presence of an association between atopy and the Glu237Gly FcepsilonRI-beta variant in French-Canadians. Our data suggest that a susceptibility locus for atopy is located on chromosome 11q13 in this population.

Plasticity in cerebellar tactile maps in the adult rat

We previously demonstrated that the fractured tactile cerebellar map within the crus IIa folia of the cerebellar hemispheres reorganizes after deafferentation of the upper lip in neonatal rats (postnatal day [PND] 1-30). The present study examined the capacity of this map to reorganize after deafferentation in adults and animals late in development (PND 30-89). Several months after cauterization of the infraorbital branch of the trigeminal nerve, the tactile map in the granule cell layer of crus IIa reorganized, with representations of intact structures expanding into the denervated area. The pattern of reorganization was similar to reorganization after neonatal lesions in that (1) all representations were from perioral structures, (2) the reorganized map maintained a fractured somatotopy, and (3) the denervated area was predominantly and consistently invaded by the upper incisor representation. We conclude that the spatial pattern of reorganization is essentially the same regardless of the age of deafferentation. However, we also observed developmental differences in reorganization. First, more areas of crus IIa were nonresponsive in animals lesioned later in development (PND 30-89). Second, we found a surprising degree of variability in the pattern of tactilely evoked cerebellar field potentials of PND 30-40 animals compared with neonates and adults, suggesting that this time period differs from other stages. The pattern of evoked potentials reflects the two primary inputs to the map. Our data show that, although both afferent pathways are capable of reorganization throughout development, their relative contribution to the map appears to differ, depending on the age at which lesion occurs.

Genome-wide search for linkage of bipolar affective disorders in a very large pedigree derived from a homogeneous population in quebec points to a locus of major effect on chromosome 12q23-q24

We completed a genome-wide scan for susceptibility loci for bipolar affective disorders in families derived from a rather homogeneous population in the Province of Québec. The genetic homogeneity of this population stems from the migration of founding families into this relatively isolated area of Québec in the 1830s. A possible founder effect, combined with a prevalence of very large families, makes this population ideal for linkage studies. Genealogies for probands can be readily constructed from a population database of acts of baptism and marriage from the early 1830s up to the present time (the BALSAC register). We chose probands with a DSM III diagnosis of bipolar affective disorder and who may be grouped within large families having genealogical origins with the founding population of the Saguenay-Lac-St-Jean area. Living members (n approximately 120) of a very large pedigree were interviewed using the Structured Clinical Interview for DSM III (SCID I), SCID II, and with a family history questionnaire. A diagnostic panel evaluated multisource information (interview, medical records, family history) and pronounced best-estimate consensus diagnoses on all family members. Linkage, SimAPM, SimIBD, and sib-pair analyses have been performed with 332 microsatellite probes covering the entire genome at an average spacing of 11 cM. GENEHUNTER and haplotype analyses were performed on regions of interest. Analysis of a second large pedigree in the same regions of interest permitted confirmation of presumed linkages found in the region of chromosome 12q23-q24.

Chromosome 13 workshop report

Evidence was presented that provided support for linkage in a relatively broad telomeric region of chromosome 13. A significant overlap for positive markers linked to both bipolar disorder and schizophrenia occurred in this area.

Fine mapping of low-density lipoprotein receptor gene by genetic linkage on chromosome 19p13.1-p13.3 and study of the founder effect of four French Canadian low-density lipoprotein receptor gene mutations

Familial hypercholesterolemia (FH) is one of the most common autosomal codominant diseases. FH is caused by mutations in the low-density lipoprotein receptor (LDLR) gene and is characterized by raised plasma LDL-cholesterol, tendon xanthomas, and premature coronary heart disease. The frequency of FH among French Canadians in northeastern Quebec is higher than in most other populations, 1:154 vs. 1:500 due to high prevalence of few recurrent mutations in the LDLR gene. In the French Canadian population, 11 mutations in the LDLR gene have been found to occur in geographically diverse areas and account for > 90% of cases. We have first constructed a high-resolution genetic map to locate several highly polymorphic markers close to LDLR locus, thus providing the necessary tools to study the origin of the four most common mutations which account for approximately 80% of our FH patients. We have then genotyped five markers (D19S413, D19S865, D19S221, D19S914, D19S586) in 102 heterozygotes (38 del > 15kb; 36 W66G; 16 C646Y; 12 E207K), two compound heterozygotes (del > 15kb/W66G; del > 15kb/C646Y) and seven homozygotes (three del > 15 kb; three W66G: one E207K) with FH unrelated to the first and second degree. We have found that patients bearing the same LDLR gene mutation carry a common haplotype at the LDLR locus although there is evidence for the early occurrence of a recombinational event between the LDLR and the D19S221 locus in the French Canadian patients bearing the W66G mutation. The fine mapping of LDLR gene close to several highly informative microsatellite markers provide fine mapping details of the LDLR region and additional tools for studies of association between plasma lipoprotein levels and LDLR gene.

Mutations of the forkhead/winged-helix gene, FKHL7, in patients with Axenfeld-Rieger anomaly

Genetic linkage, genome mismatch scanning, and analysis of patients with alterations of chromosome 6 have indicated that a major locus for development of the anterior segment of the eye, IRID1, is located at 6p25. Abnormalities of this locus lead to glaucoma. FKHL7 (also called "FREAC3"), a member of the forkhead/winged-helix transcription-factor family, has also been mapped to 6p25. DNA sequencing of FKHL7 in five IRID1 families and 16 sporadic patients with anterior-segment defects revealed three mutations: a 10-bp deletion predicted to cause a frameshift and premature protein truncation prior to the FKHL7 forkhead DNA-binding domain, as well as two missense mutations of conserved amino acids within the FKHL7 forkhead domain. Mf1, the murine homologue of FKHL7, is expressed in the developing brain, skeletal system, and eye, consistent with FKHL7 having a role in ocular development. However, mutational screening and genetic-linkage analyses excluded FKHL7 from underlying the anterior-segment disorders in two IRID1 families with linkage to 6p25. Our findings demonstrate that, although mutations of FKHL7 result in anterior-segment defects and glaucoma in some patients, it is probable that at least one more locus involved in the regulation of eye development is also located at 6p25.

A physical map of 30,000 human genes

A map of 30,181 human gene-based markers was assembled and integrated with the current genetic map by radiation hybrid mapping. The new gene map contains nearly twice as many genes as the previous release, includes most genes that encode proteins of known function, and is twofold to threefold more accurate than the previous version. A redesigned, more informative and functional World Wide Web site (www.ncbi.nlm.nih.gov/genemap) provides the mapping information and associated data and annotations. This resource constitutes an important infrastructure and tool for the study of complex genetic traits, the positional cloning of disease genes, the cross-referencing of mammalian genomes, and validated human transcribed sequences for large-scale studies of gene expression.

Type I protein C deficiency in French Canadians: evidence of a founder effect and association of specific protein C gene mutations with plasma protein C levels

Protein C (PROC) deficiency is one of the most common autosomal codominant diseases. Although more than 150 germline mutations in the PROC gene have been described around the world, the spectrum of mutations among French Canadians is unknown. We have identified one frameshift (3363 ins C) and two missense mutations (R178Q and T298M) in 7 French Canadian families with type I PROC deficiency. In order to demonstrate a possible founder effect for the 3363 ins C mutation, we have constructed a high-resolution genetic map to locate several highly polymorphic markers close to PROC locus. We have then genotyped five markers in 36 heterozygotes for the 3363 ins C mutation. Our data suggest that these patients carry a common haplotype at the PROC locus. Immunologic plasma PROC levels of heterozygotes and genetically normal relatives were also correlated with the nature of the mutation in the coding sequence and with the genotype of three polymorphisms in the PROC promoter. We found that the mean immunologic plasma PROC levels were lower in heterozygotes for the frameshift mutation 3363 ins C compared to heterozygotes for one of the two missense mutations R178Q and T298M (0.46 vs 0.61; P = 0.0004). Moreover, this difference cannot be explained by the genetic variation of the three polymorphisms in the PROC promoter which accounts for only 10.4% of the variation of immunologic PROC levels in non-deficient subjects. These results suggest that the nature of the mutation in the coding sequence of PROC gene may modulate immunologic plasma PROC levels.

Genetic linkage mapping of the CYP11A1 gene encoding the cholesterol side-chain cleavage P450scc close to the CYP1A1 gene and D15S204 in the chromosome 15q22.33-q23 region

The first rate-limiting step in the biosynthesis of all mammalian steroid hormones is the conversion of cholesterol to pregnenolone by the cholesterol side-chain cleavage enzyme, P450scc. The human CYP11A1 gene, encoding the mitochondrial P450scc, has been previously assigned by in situ hybridization to 15q23-q24 region. To map the CYP11A1 gene with linkage analysis, a novel TAAAA repeat polymorphism, found in its promoter region, was genotyped in the eight largest CEPH reference families, which included 91 children, 16 parents and 26 grandparents. Two-point linkage analysis was performed between this tetra-allelic polymorphism and the chromosome 15 microsatellite markers of Généthon as well as the tetranucleotide polymorphism of the CYP19 gene and a MspI RFLP of the CYP1A1 gene. A close linkage was observed with D15S204 (Z max = 27.33; theta max = 0.009) and CYP1A1 gene (Z max = 6.62; theta max = 0.001), but not with the CYP19 gene (Z max = 4.06; theta max = 0.26). The CYP19 gene that encodes the P450arom was rather closely linked with D15S123 (Z max = 31.04; theta max = 0.001). A framework map, including Généthon markers flanking the polymorphic CYP11A1 and CYP19 genes, was built by multipoint linkage analysis. Thereafter, a high-resolution genetic map of the 15q15-q25.3 region was constructed, yielding to the following order: cen-D15S214-[D15S123; CYP19]-D15S117-D15S159-D15S153-D15S983-[++ +D15S204; CYP11A1; CYP1A1]-D15S211-D15S152-D15S199-tel. Thus, the CYP11A1 gene is closely linked with the CYP1A1 gene, whereas it is located approximately 27.4 cM telomeric to the CYP19 gene.