Trinucleotide repeat polymorphism in the androgen receptor gene (AR)

Improved HUMARA for the Detection of X-Linked Agammaglobulinemia Carriers

Background: Fragment analysis of exon 1 of the human androgen receptor, known as HUMARA, is a polymerase chain reaction (PCR)-based method for detecting X-linked agammaglobulinemia (XLA) carriers. This method takes advantage of X-chromosome inactivation (XCI) in female cells. XLA is caused by mutations in the Bruton tyrosine kinase (BTK) gene, located in Xq22.1. In this study, XCI is nonrandom or skewed in B cells. B cells with an active X-chromosome carrying a BTK mutation do not mature. Peripheral B cells in XLA carriers inactivate the mutated X-chromosome. Methods: HUMARA was performed using DNA from purified B cells and total leukocytes. DNA was digested using methylation-sensitive HhaI. The PCR of the HUMARA polymorphic marker was performed with the HhaI digested samples. The lengths of the PCR product were determined. If a suspected carrier showed skewed XCI in B cells, the marker length that corresponded with the length determined in the index patient indicated their carrier status. Results: HUMARA was conducted on purified B cells; this allowed easier identification of the mutated or inactive allele, as the active allele was enzymatically digested. Analysis of 30 possible carriers using modified HUMARA corroborated that the carrier status in all samples that were heterozygous for the marker using XCI calculation for leukocytes showed a Gaussian distribution, while the carrier B cell DNA showed a skewed XCI. Conclusion: Carrier status was successfully determined for most of the analyzed samples. B cell enrichment resulted in precise carrier determination data, reduced the sample size, and facilitated inactive and active allele identification.

Twenty Years Later: A Comprehensive Review of the X Chromosome Use in Forensic Genetics

The unique structure of the X chromosome shaped by evolution has led to the present gender-specific genetic differences, which are not shared by its counterpart, the Y chromosome, and neither by the autosomes. In males, recombination between the X and Y chromosomes is limited to the pseudoautosomal regions, PAR1 and PAR2; therefore, in males, the X chromosome is (almost) entirely transmitted to female offspring. On the other hand, the X chromosome is present in females with two copies that recombine along the whole chromosome during female meiosis and that is transmitted to both female and male descendants. These transmission characteristics, besides the obvious clinical impact (sex chromosome aneuploidies are extremely frequent), make the X chromosome an irreplaceable genetic tool for population genetic-based studies as well as for kinship and forensic investigations. In the early 2000s, the number of publications using X-chromosomal polymorphisms in forensic and population genetic applications increased steadily. However, nearly 20 years later, we observe a conspicuous decrease in the rate of these publications. In light of this observation, the main aim of this article is to provide a comprehensive review of the advances and applications of X-chromosomal markers in population and forensic genetics over the last two decades. The foremost relevant topics are addressed as: (i) developments concerning the number and types of markers available, with special emphasis on short tandem repeat (STR) polymorphisms (STR nomenclatures and practical concerns); (ii) overview of worldwide population (frequency) data; (iii) the use of X-chromosomal markers in (complex) kinship testing and the forensic statistical evaluation of evidence; (iv) segregation and mutation studies; and (v) current weaknesses and future prospects.

Lower prostate cancer risk in Swedish men with the androgen receptor E213 A-allele

Background

In a previous population-based study on 3369 European men with self-reported prostate cancer (PCa), it was shown that androgen receptor (AR) haplotype designated H2 was associated with high levels of serum PSA (prostate-specific antigen) concentration, and, at the same time, with low risk for PCa. The aim of this study was to replicate this finding in other cohorts, with registry-based cancer diagnosis.

Methods

Using data from two population-based cohorts; the Malmö Diet and Cancer Study (MDCS, n = 12,121) and the Swedish Osteoporotic fractures in men study (MrOS, n = 1,120), 628 men with PCa and 1,374 controls were identified and genotyped. PCa data were collected from the Swedish national cancer registry. PCa odds ratios (ORs) and 95% confidence intervals (CIs) were calculated for carriers of the particular AR haplotype, tagged by the rs6624304 T-allele.

Results

The 15% of men who were carriers of the AR haplotype H2 had approximately one-third lower risk for PCa diagnosis compared to those with the most common H1 variant (OR 0.65; 95% CI 0.45–0.94; p = 0.021). The same trend, although not statistically significant (OR 0.75; 95% CI 0.47–1.24; p = 0.275), was observed in MrOS Sweden. When both cohorts were merged, an even more significant result was observed (OR 0.68; 95% CI 0.51–0.90; p = 0.008).

Conclusions

Swedish men with the variant AR haplotype H2, tagged by rs6624304, have significantly lower risk of PCa compared to those with the more common variant.

Association of androgen receptor CAG repeat polymorphism and risk of epithelial ovarian cancer

BACKGROUND

Biological and epidemiologic evidence suggested that androgen and its receptor may play an important role in ovarian carcinogenesis. However, results of previous association studies about ovarian cancer and AR CAG repeat polymorphism were inconsistent. Furthermore, none of these studies were conducted in Asians.

METHODS

We evaluated the relationship between AR CAG repeat length and epithelial ovarian cancer (EOC) risk among a Chinese population including 1800 pathologically confirmed EOC patients and 1800 frequency matched controls.

RESULTS

Women with longer AR CAG repeats had a decreased EOC risk (OR=0.87 for per CAG_A increase, 95% CI: 0.81-0.95). Compared to those with shorter (<22) CAG_A repeat length, women with of longer (≥22) CAG_A repeats had a 34% decreased EOC risk (OR=0.66, 95% CI: 0.57-0.75). For CAG_S and CAG_L, the results remained consistent.

CONCLUSIONS

Our findings suggest that androgen signaling contributes to the development of ovarian cancer.

Indolent T-lymphoblastic proliferation with disseminated multinodal involvement and partial CD33 expression

Although indolent T-lymphoblastic proliferations (iT-LBP) are rare, this diagnosis should be excluded in any patient with an extrathymic proliferation of immature TdT+T cells. Unlike T-lymphoblastic leukemia/lymphoma, patients with iT-LBP do not require chemotherapy. We report a case of iT-LBP with disseminated multinodal involvement in an otherwise healthy 49-year-old woman. Multiple lymph node biopsies were performed over the course of several months demonstrating persistent and anatomically diffuse involvement. Over 18 months, and without therapy, she has remained healthy, and her lymphadenopathy significantly improved. No bone marrow or peripheral blood involvement was ever identified. Atypical T cells showed an immunophenotypic spectrum of T-cell antigen expression with partial CD33 on a subset of T cells detected by both flow cytometry and immunohistochemistry. Both T-cell clonality and Human Androgen Receptor Assay (HUMARA) studies, performed on lymph node biopsy specimens, were negative. This case represents the first detailed clinical, morphologic, molecular, and immunophenotypic description of disseminated multinodal involvement by nonclonal iT-LBP with partial CD33 expression on T cells.

Three new loci for determining x chromosome inactivation patterns

The analysis of X chromosome inactivation (XCI) patterns is a widely used diagnostic tool in clinical practice when investigating X-linked diseases. The most commonly used assay to determine XCI patterns takes advantage of a locus within the androgen receptor (AR) gene. This PCR-based assay relies on two differentially methylated restriction enzyme sites (HpaII) and a polymorphic repeat located within this locus. Although highly informative, this locus is not always sufficient to evaluate the X-inactivation status in X-linked disorders. We have identified three new loci that can be used to determine XCI patterns in a methylation-sensitive PCR-based assay. All three loci contain polymorphic repeats and a methylation-sensitive restriction enzyme (HpaII) site, methylation of which was shown to correlate with XCI. DNA from 60 females was used to estimate the heterozygosity of these new loci. The reliability of the loci was validated by showing a high correlation between the results obtained by employing the new loci and the AR locus using DNA from 15 females who were informative for all four loci. Altogether, we show that these loci can be applied easily in molecular diagnostic laboratories, either as a supplement or as an alternative to the existing AR assay.

Molecular mechanisms of androgen action--a historical perspective

Androgens and the androgen receptor (AR) are indispensable for expression of the male phenotype. The two most important androgens are testosterone and 5α-dihydrotestosterone. The elucidation of the mechanism of androgen action has a long history starting in the 19th century with the classical experiments by Brown-Séquard. In the 1960s the steroid hormone receptor concept was established and the AR was identified as a protein entity with a high affinity and specificity for testosterone and 5α-dihydrotestosterone. In addition, the enzyme 5α-reductase type 2 was discovered and found to catalyze the conversion of testosterone to the more active metabolite 5α-dihydrotestosterone. In the second half of the 1980s, the cDNA cloning of all steroid hormone receptors, including that of the AR, has been another milestone in the whole field of steroid hormone action. Despite two different ligands (testosterone and 5α-dihydrotestosterone), only one AR cDNA has been identified and cloned. The AR (NR3C4) is a ligand-dependent transcription factor and belongs to the family of nuclear hormone receptors which has 48 members in human. The current model for androgen action involves a multistep mechanism. Studies have provided insight into AR association with co-regulators involved in transcription initiation and on intramolecular interactions of the AR protein during activation. Knowledge about androgen action in the normal physiology and in disease states has increased tremendously after cloning of the AR cDNA. Several diseases, such as androgen insensitivity syndrome (AIS), prostate cancer and spinal bulbar muscular atrophy (SBMA), have been shown to be associated with alterations in AR function due to mutations in the AR gene or dysregulation of androgen signalling. A historical overview of androgen action and salient features of AR function in normal and disease states are provided herein.

Systematic molecular genetic analysis of congenital sideroblastic anemia: evidence for genetic heterogeneity and identification of novel mutations

BACKGROUND

Sideroblastic anemias are heterogeneous congenital and acquired bone marrow disorders characterized by pathologic iron deposits in mitochondria of erythroid precursors. Among the congenital sideroblastic anemias (CSAs), the most common form is X-linked sideroblastic anemia, due to mutations in 5-aminolevulinate synthase (ALAS2). A novel autosomal recessive CSA, caused by mutations in the erythroid specific mitochondrial transporter SLC25A38, was recently defined. Other known etiologies include mutations in genes encoding the thiamine transporter SLC19A2, the RNA-modifying enzyme pseudouridine synthase 1 (PUS1), a mitochondrial ATP-binding cassette transporter (ABCB7), glutaredoxin 5 (GLRX5), as well as mitochondrial DNA deletions. Despite these known diverse causes, in a substantial portion of CSA cases a presumed genetic defect remains unknown.

PROCEDURE

In the context of the recent discovery of SLC25A38 as a major novel cause, we systematically analyzed a large cohort of previously unreported CSA patients. Sixty CSA probands (28 females, 32 males) were examined for ALAS2, SLC25A38, PUS1, GLRX5, and ABCB7 mutations. SLC19A2 and mitochondrial DNA were only analyzed if characteristic syndromic features were apparent.

RESULTS

Twelve probands had biallelic mutations in SLC25A38. Seven ALAS2 mutations were detected in eight sporadic CSA cases, two being novel. We also identified a novel homozygous null PUS1 mutation and novel mitochondrial DNA deletions in two patients with Pearson syndrome. No mutations were encountered in GLRX5, ABCB7, or SLC19A2.

CONCLUSIONS

The remaining undefined probands (43%) can be grouped according to gender, family, and clinical characteristics, suggesting novel X-linked and autosomal recessive forms of CSA.

A novel sequence variation in the transactivation regulating domain of the human androgen receptor

OBJECTIVE

To study a novel sequence variation within the androgen receptors' N-terminal CAG repeat region and possible resulting consequences for the receptors' three-dimensional (3D) protein structure.

DESIGN

Controlled clinical study.

SETTING

University research and andrology clinic.

PATIENT(S)

Twenty-one adult infertile men.

INTERVENTION(S)

Ultraviolet laser-assisted microdissection (PALM, Microlaser Technology AG, Bernried, Germany), cloning into pGEM-T vector (Promega, Madison, WI), automated sequencing (Gene Scan 3.7 ABI Prim, Applied Biosystems, Foster City, CA), and Assisted Model Building with Energy Refinement (AMBER).

MAIN OUTCOME MEASURE(S)

Determination of the sequence of the CAG repeat of the androgen receptor gene and analysis of the 3D protein structure.

RESULTS(S)

In one hypergonadotropic azoospermic patient with Sertoli-cell-only syndrome, we found a punctual sequence variation of 212A-->G in the CAG repeat resulting in a glutamine-arginine substitution, which leads to a moderate conformational change of the alpha-helix from 34 A in length and 16 A in diameter (without mutation) to a slightly longer helix (43 A) with a smaller diameter (15 A).

CONCLUSION(S)

Whether the novel 212A-->G exchange in the CAG repeat leading to a glutamine-->arginine substitution and a change in alpha-helix structure may causally be related to the Sertoli-cell-only phenotype of the patient remains to be elucidated.

Huntingtin associated protein 1 and its functions

Huntington disease (HD) is caused by a polyglutamine expansion in the protein huntingtin (Htt). Several studies suggest that Htt and huntingtin associated protein 1 (HAP1) participate in intracellular trafficking and that polyglutamine expansion affects vesicular transport. Understanding the function of HAP1 and its related proteins could help elucidate the pathogenesis of HD. The present review focuses on HAP1, which has proved to be involved in intracellular trafficking. Unlike huntingtin, which is expressed ubiquitously throughout the brain and body, HAP1 is enriched in neurons, suggesting that its dysfunction could contribute to the selective neuropathology in HD. We discuss recent evidence for the involvement of HAP1 and its binding proteins in potential functions.

Skewed X chromosome inactivation and breast and ovarian cancer status: evidence for X-linked modifiers of BRCA1

BACKGROUND

X chromosome inactivation, which silences gene expression from one of the two X chromosomes in females, is usually random. Skewed X inactivation has been implicated in both the expression and the suppression of X-linked disease phenotypes and has been reported to occur more frequently in breast and ovarian cancer patients, including BRCA1 or BRCA2 mutation carriers, than in control subjects.

METHODS

We assessed the pattern of X chromosome inactivation using methylation-specific polymerase chain reaction amplification of the exon 1 microsatellite region of the X-linked androgen receptor (AR) gene in DNA from blood samples obtained from control subjects without a personal history of breast or ovarian cancer (n = 735), ovarian cancer patients (n = 313), familial breast cancer patients who did not carry mutations in BRCA1 or BRCA2 (n = 235), and affected and unaffected carriers of mutations in BRCA1 (n = 260) or BRCA2 (n = 63). We defined the pattern of X chromosome inactivation as skewed when the same X chromosome was active in at least 90% of cells. The association between skewed X inactivation and disease and/or BRCA mutation status was assessed by logistic regression analysis. The association between skewed X inactivation and age at cancer diagnosis was assessed by Cox proportional hazards regression analysis. All statistical tests were two-sided.

RESULTS

The age-adjusted frequency of skewed X inactivation was not statistically significantly higher in ovarian cancer or familial breast cancer case subjects compared with control subjects. Skewed X inactivation was higher in BRCA1 mutation carriers than in control subjects (odds ratio [OR] = 2.7, 95% confidence interval [CI] = 1.1 to 6.2; P = .02), particularly among unaffected women (OR = 6.1, 95% CI = 1.5 to 31.8; P = .005). Among BRCA1 mutation carriers, those with skewed X inactivation were older at diagnosis of breast or ovarian cancer than those without skewed X inactivation (hazard ratio [HR] of breast or ovarian cancer = 0.37, 95% CI = 0.14 to 0.95; P = .04). Among BRCA2 mutation carriers, skewed X inactivation also occurred more frequently in unaffected carriers than in those diagnosed with breast or ovarian cancer (OR = 5.2, 95% CI = 0.5 to 28.9; P = .08) and was associated with delayed age at onset (HR = 0.59, 95% CI = 0.37 to 0.94; P = .03).

CONCLUSIONS

Skewed X inactivation occurs at an increased frequency in BRCA1 (and possibly BRCA2) mutation carriers compared with control subjects and is associated with a statistically significant increase in age at diagnosis of breast and ovarian cancer.

Association between polymorphisms in the prostate-specific antigen (PSA) promoter and release of PSA

Variations in serum prostate-specific antigen (PSA) have been ascribed to A/G nucleotide polymorphisms located at -158 bp (rs266882) and -4643 bp (rs925013), relative to the transcription start site within the promoter of the PSA gene. PSA is also an androgen receptor target (AR) gene and polymorphisms in AR gene are known to affect AR function. Our objective was to compare the impact of these A/G polymorphisms separately or in combination with AR CAG micro satellite on regulation of PSA secretion into seminal plasma and blood in young men. Leukocyte DNA was extracted from 291 conscripts and genotyping performed with the Sequenom Mass Array System. PSA was measured with an immunofluorometric assay. Linear regression analysis was used to test the association of polymorphism frequencies with serum and seminal plasma levels of PSA. PSA gene polymorphisms at -158 bp or -4643 bp did not alone influence total PSA (tPSA) levels in seminal plasma or in blood. Homozygotes for the A-allele at -158 bp in combination with CAG > 22 had significantly higher serum levels of tPSA than subjects carrying the G-allele (p = 0.01). In conclusion, the PSA gene polymorphisms did not importantly influence the levels of tPSA in seminal plasma or in blood. tPSA in serum was influenced by interactions between PSA promoter variants and AR CAG polymorphism.

Trinucleotide repeat polymorphisms in the androgen receptor gene and risk of ovarian cancer

INTRODUCTION

Androgens may play a role in the development of ovarian cancers. Two trinucleotide repeat polymorphisms have been described in exon 1 of the androgen receptor (AR) gene that may affect its function. Previous studies of ovarian cancer and AR repeat polymorphisms have been inconsistent.

METHODS

We analyzed CAG and GGC repeat length polymorphisms in the AR gene using data from a population-based case-control study of ovarian cancer that included 594 cases and 681 controls. Repeat lengths were determined by fluorescent DNA fragment analysis using ABI GeneScan software. Change point models were used to determine appropriate repeat length cutoff points by race (African American versus Caucasian) for both the shorter and longer CAG and GGC repeats.

RESULTS

No relationship was observed between CAG repeat length and ovarian cancer among Caucasians. Among African Americans, having a short repeat length on either allele was associated with a 2-fold increase in ovarian cancer risk (age-adjusted odds ratio, 2.2; 95% confidence interval, 1.1-4.1). Having short CAG repeat lengths for both alleles was associated with a 5-fold increased risk for developing ovarian cancer (age-adjusted odds ratio, 5.4; 95% confidence interval, 1.4-1.7). No relationship with the GGC repeat length polymorphisms was observed.

CONCLUSION

These results suggest that having a short CAG repeat length in AR increases ovarian cancer risk in African Americans. The failure to observe this relationship in Caucasians may be due to the rarity of such short CAG alleles in this population or could reflect racial differences in disease etiology.

DNA and kinetic heterogeneity during the clonal evolution of adrenocortical proliferative lesions

Monoclonal adrenocortical lesions show inverse correlation between proliferation and apoptosis, with proliferation being the single most important criterion of malignancy in adrenal lesions. No study yet has evaluated the variability of proliferation regarding the clonal pattern and diagnosis in adrenocortical nodular hyperplasias (ACNHs), adrenocortical adenomas (ACAs), and adrenocortical carcinomas (ACCs). We studied 69 ACNHs, 64 ACAs, and 23 ACCs (World Health Organization criteria) from 156 females. Clonality HUMARA test (from microdissected DNA samples), DNA content and proliferation analysis (slide and flow cytometry), and mitotic figure (MF) counting/50 high-power fields (HPFs) were performed in the same areas. Heterogeneity was assessed by 5cER (percentage of nonoctaploid cells with DNA content exceeding 5c) and standard deviation of MF/HPF. Statistics included analysis of variance/Student t tests regarding the clonal patterns and diagnosis. Polyclonal patterns were observed in 48 of 62 informative ACNHs and 7 of 56 informative ACAs, and monoclonal in 14 of 62 ACNHs, 49 of 56 ACAs, and 21 of 21 ACCs, with all hyperdiploid lesions (14 ACCs and 13 ACAs) being monoclonal. The standard deviation of MF/HPF progressively increased in ACNH-ACA-ACC (0.048 +/- 0.076, 0.110 +/- 0.097, 0.506 +/- 0.291, respectively; P = .0023), but did not differentiate ACNH/ACA. Only tetraploid percentage (P = .0496) and 5cER (P = .0352) distinguished polyclonal (3.64 +/- 2.20 and 0.14 +/- 0.15) from monoclonal (7.25 +/- 7.52 and 1.00 +/- 1.74) benign lesions. Malignancy significantly correlated with a low diploid percentage and high tetraploid percentage. Cell kinetic heterogeneity is the hallmark of adrenocortical neoplasms: tetraploid/hypertetraploid cell accumulation characterizes monoclonal lesions (suggesting nondisjunctional mitoses), whereas heterogeneously distributed mitotic figures and decreased diploid percentage define ACCs.

Huntingtin-associated protein 1 (HAP1) interacts with androgen receptor (AR) and suppresses SBMA-mutant-AR-induced apoptosis

Huntingtin-associated protein 1 (HAP1), an interactor of huntingtin, has been known as an essential component of the stigmoid body (STB) and recently reported to play a protective role against neurodegeneration in Huntington's disease (HD). In the present study, subcellular association between HAP1 and androgen receptor (AR) with a long polyglutamine tract (polyQ) derived from spinal-and-bulbar-muscular-atrophy (SBMA) was examined using HEp-2 cells cotransfected with HAP1 and/or normal ARQ25, SBMA-mutant ARQ65 or deletion-mutant AR cDNAs. The results provided the first clear evidence that HAP1 interacts with AR through its ligand-binding domain in a polyQ-length-dependent manner and forms prominent inclusions sequestering polyQ-AR, and that addition of dihydrotestosterone reduces the association strength of HAP1 with ARQ25 more dramatically than that with ARQ65. Furthermore, SBMA-mutant-ARQ65-induced apoptosis was suppressed by cotransfection with HAP1. Our findings strongly suggest that HAP1/STB is relevant to polyQ-length-dependent modification on subcellular AR functions and critically involved in pathogenesis of not only HD but also SBMA as an important intrinsic neuroprotectant determining the threshold for cellular vulnerability to apoptosis. Taking together with previous reports that HAP1/STB is selectively expressed in the brain regions spared from degenerative targets in HD and SBMA, the current study might explain the region-specific occurrence of neurodegeneration in both diseases, shedding light on common aspects of their molecular pathological mechanism and yet-to-be-uncovered diagnostic or therapeutic applications for HD and SBMA patients.

The 5α-Reductase Type II A49T and V89L High-Activity Allelic Variants are More Common in Men with Prostate Cancer Compared with the General Population

OBJECTIVES

To compare men with prostate disease with those from the general population regarding polymorphisms in the androgen receptor gene and in the 5alpha-reductase II (SRD5A2) gene.

MATERIALS AND METHODS

The SRD5A2 polymorphisms A49T, V89L and R227Q, the androgen receptor CAG and GGN repeats and sex hormone status was investigated in men with prostate cancer (CaP) (n=89), benign prostate hyperplasia (n=45) and healthy military conscripts (n=223).

RESULTS

The SRD5A2 high-activity allele variants A49T AT and V89L LL were more frequent in CaP-patients compared to general population, p=0.026 and p=0.05, respectively. CaP progression was, however, independent of SRD5A2 variants. In contrary, men with GGN<23 had a higher risk of dying from the disease than their counterparts with longer repeats.

CONCLUSIONS

Men with CaP were more often genetically predisposed to a higher enzymatic activity in the turn over from T to DHT compared to the general population. In our population, androgen receptor genotype affected CaP outcome.

Polymorphic forms of prostate specific antigen and their interaction with androgen receptor trinucleotide repeats in prostate cancer

BACKGROUND

Recent data has suggested that polymorphisms in the prostate specific antigen (PSA) may increase prostate cancer (PC) risk. The PSA gene contains a G/A substitution in the androgen response element (ARE) 1 region. The androgen receptor (AR) gene has polymorphic regions containing variable length glutamine and glycine repeats and these are believed to be associated with PC risk. The effect on PC risks from PSA polymorphisms alone and synergistically with the AR gene was examined in this report.

METHODS

One hundred PC patients and an age matched cohort of 79 benign prostate hyperplasia and 67 population controls were entered in this study. DNA was extracted from blood and PSA/ARE promoter region amplified by PCR. PCR products were cut with Nhe 1 restriction enzyme to distinguish G/A alleles. AR/CAG and GGC repeat length was detected by automated fluorescence from PCR products.

RESULTS

We found a significantly higher PSA/GG distribution in PC (30%) than either benign prostatic hyperplasia (BPH) (18%) or population controls (16%) (P = 0.025). Furthermore the GG distribution within cases was even greater in younger men (< 65 years; 42%; P = 0.012). Additionally, when PSA genotype was cross classified with CAG repeat, significantly more cases than both BPH and population controls were observed to have a short (< 22) CAG/GG genotype (P = 0.006).

CONCLUSIONS

Our results indicate that the PSA/ARE GG genotype confers an increased risk of PC especially among younger men. Moreover, we confirm previous results that a short glutamine repeat in conjunction with GG genotype significantly increases the risk of malignant disease.

Investigation of hormone receptor genes in migraine

Migraine is a common neurological condition with a complex mode of inheritance. Steroid hormones have long been implicated in migraine, although their role remains unclear. Our investigation considered that genes involved in hormonal pathways may play a role in migraine susceptibility. We therefore investigated the androgen receptor (AR) CAG repeat, and the progesterone receptor (PR) PROGINS insert by cross-sectional association analysis. The results showed no association with the AR CAG repeat in our study group of 275 migraineurs and 275 unrelated controls. Results of the PR PROGINS analysis showed a significant difference in the same cohort, and in an independent follow-up study population of 300 migraineurs and 300 unrelated controls. Analysis of the genotypic risk groups of both populations together indicated that individuals who carried the PROGINS insert were 1.8 times more likely to suffer migraine. Interaction analysis of the PROGINS variant with our previously reported associated ESR1 594A variant showed that individuals who possessed at least one copy of both risk alleles were 3.2 times more likely to suffer migraine. Hence, variants of these steroid hormone receptor genes appear to act synergistically to increase the risk of migraine by a factor of three.

Gene Regulation in Spermatogenesis

Mammalian spermatogenesis is a complex hormone-dependent developmental program in which a myriad of events must take place to ensure that germ cells reach their proper stage of development at the proper time. Many of these events are controlled by cell type- and stage-specific transcription factors. The regulatory mechanisms involved provide an intriguing paradigm for the field of developmental biology and may lead to the development of new contraceptives an and innovative routs to treat male infertility. In this review, we address three aspects of the genetic regulatory mechanism that drive spermatogenesis. First, we detail what is known about how steroid hormones (both androgens and estrogens) and their cognate receptors initiate and maintain mammalian spermatogenesis. Steroids act through three mechanistic routes: (i) direct activation of genes through hormone-dependent promoter elements, (ii) secondary transcriptional responses through activation of hormone-dependent transcription factors, and (iii) rapid, transcription-independent (nonclassical) events induced by steroid hormones. Second, we provide a survey of transcription factors that function in mammalian spermatogenesis, including homeobox, zinc-finger, heat-shock, and cAMP-response family members. Our survey is not intended to cover all examples but to give a flavor for the gamut of biological roles conferred by transcription factors in the testis, particularly those defined in knockout mice. Third, we address how testis-specific transcription is achieved. In particular, we cover the evidence for and against the idea that some testis-specific genes are transcriptionally silent in somatic tissues as a result of DNA methylation.

Linkage between androgen receptor gene CAG trinucleotide repeat length and testicular germ cell cancer histological type and clinical stage

Sex hormones and/or gonadotropins may play a crucial role in the development of testicular germ cell cancer (TGCC). A direct link between this malignancy and endocrine factors has not been confirmed. We tested whether CAG and GGN repeats of the androgen receptor gene (AR) play a role in the aetiology or pathogenesis of TGCC. Eighty-three TGCC patients and 220 controls were included. Mean CAG or GGN lengths did not differ between the TGCC cases and controls. The proportion of males with CAG lengths above 25, indicative of reduced androgen sensitivity, was significantly lower among patients with pure seminomas and in the combined group of seminomas and mixed tumours compared with non-seminomas and controls. The median CAG length was higher if the tumour was metastasing at diagnosis. This is the first study showing an association between the AR polymorphism and histological type as well as the progression rate of TGCC.

Androgen receptor CAG repeat length correlates with semen PSA levels in adolescence

BACKGROUND

Androgens exert their action through the androgen receptor (AR). The length of the AR CAG repeat is inversely correlated to receptor function and short CAG length might be a risk factor for development of prostate cancer. Our aim was to investigate whether CAG repeat number might have an impact on prostate function in adolescence.

METHODS

AR genotyping was performed by direct sequencing of leukocyte DNA from 274 military conscripts. All men underwent endocrine evaluation and semen analysis.

RESULTS

PSA in seminal plasma, total sperm count and motility all are inversely correlated with CAG numbers (rho = -0.128, P = 0.038; rho = -0.156, P = 0.010; rho = -0.158, P = 0.011), whereas serum levels of free testosterone (rho = 0.132; P = 0.029) and luteinizing hormone (rho = 0.126; P = 0.037) are positively correlated to CAG length. No correlation between seminal PSA and serum testosterone, neither free nor total, was found.

CONCLUSIONS

In adolescence, AR genotype, but not serum testosterone, is associated with the level of seminal PSA.

The polyglycine and polyglutamine repeats in the androgen receptor gene in Japanese and Caucasian populations

Human androgen receptor (AR) gene contains two polymorphic trinucleotide repeats of CAG and GGC, which code for polyglutamine and polyglycine tracts in the N-terminal domain in which the receptor activity resides. Longer repeats induce decrease of transactivation function in the AR receptor, weaken an anti-proliferative effect on various steroid-related tissues, and may promote the carcinogenesis of these cancers, such as breast, endometrial, and ovarian cancers. However, the incidences of these steroid-related cancers are remarkably lower in Japanese than in Caucasians. We hypothesize that the GGC and CAG repeats in AR gene correspond to lower incidence of steroid-related cancers in the Japanese population. To test this hypothesis, these two polymorphic trinucleotide repeats in AR gene were genotyped in 221 Japanese and 177 Caucasians. The results of genotyping in these loci clearly show that the distribution of GGC repeat is significantly different between these populations (P<0.001). Japanese (73.7%) had 16 GGC repeats compared to 53.3% for Caucasians. Japanese (3.8%) also had 17 GGC repeats compared to 36.2% for Caucasians. No Japanese had more than 18 GGC repeats compared to 3.4% for Caucasians. The length of CAG repeats in the Japanese population was not significantly different than that of the Caucasian population, although the CAG repeats varied from 14 to 31 and 15 to 29 repeats in Japanese and German populations, respectively. This study demonstrates that the Japanese population has shorter GGC compared to the Caucasian population, which may explain the incidences of estrogen-related cancers in these populations.

Androgen receptors containing expanded polyglutamine tracts exhibit progressive toxicity when stably expressed in the neuroblastoma cell line, SH-SY 5Y

The pathogenesis of X-linked spinal and bulbar muscular atrophy (SBMA) has been traced to an expansion of repeated glutamine (Gln) residues within the amino terminus of the human androgen receptor (AR). To examine the mechanisms by which these expanded repeat ARs (Exp-ARs) are toxic to neurons, we have established and characterized a cell culture model by stably transfecting SH-SY 5Y neuroblastoma cells with cDNAs containing either normal AR (81 series; 23 Glns) or Exp-AR (902 series; 56 Glns). At a low passage number, no differences in cell morphology, growth properties, or susceptibility to toxic insults were observed between clones expressing normal AR or Exp-AR. Initially, both types of cultures were found to express similar levels of specific hormone binding in monolayer binding assays. Immunohistochemical studies demonstrated the vast majority of both the normal AR and Exp-AR were localized to the nucleus in the absence and presence of androgen. As the 902 series of clones were propagated, the Exp-AR content in the cells appeared to decline progressively. However, this decrease actually reflects a gradual disappearance of the Exp-AR cell population. No such selection occurred during the propagation of cells expressing the normal AR. This selection against cells expressing physiological levels of Exp-AR occurs in the absence of intracellular aggregates and suggests that mechanisms other than those involving the formation of aggregates underlie the observed toxicity of Exp-ARs.

The CAG repeats in exon 1 of the androgen receptor gene are significantly longer in endometrial cancer patients

Human androgen receptor (AR) gene contains polymorphic CAG repeats in the N-terminal domain that influence transcription efficiency. The CAG repeats encode a poly-glutamine tract, which has a length that is inversely and linearly related to AR activity. It has been observed that longer CAG repeats impose a lower transactivation activity on AR and have a decreased binding affinity for androgens. Androgens have an anti-proliferative effect on endometrial cells. We hypothesize that the length of CAG repeats on the AR gene can predict higher incidence of endometrial cancer. To test this hypothesis, the genetic distributions of CAG repeats on AR gene polymorphisms were investigated in endometrial cancer patients and healthy controls. Genotyping and a chi(2) test revealed that the distribution of CAG repeats was significantly different between the endometrial cancer patients and normal healthy controls (P<0.001). The endometrial cancer patients had longer alleles than normal healthy controls. The longer CAG repeats in the AR gene may cause a decrease of transactivation function in the receptor, weaken an anti-proliferative effect on uterine endometrial cells, and promote carcinogenesis of the uterine endometrial cells. The findings suggest that the CAG repeats in the AR gene may be important in the carcinogenesis of uterine endometrial cells.

Development of the X-linked tetrameric microsatellite markers HumDXS6803 and HumDXS9895 for forensic purpose

This paper presents sequence and population genetic data of the X-linked DXS6803 and DXS9895 short tandem repeat (STR). The tetranucleotide repeat polymorphism DXS6803 (also known as CHLC.GATA45H11) and DXS9895 (also known as CHLC.GATA124B04) are located at the Xq12-Xq21.33 and Xpter-Xp22.2 region, respectively. In kinship testing, DXS6803 and DXS9895 are suitable for concomitant use. Population genetic data were obtained by analyzing 182 unrelated females and 110 males from Chinese Han population. In this population, both DXS6803 and DXS9895 exhibited seven clearly distinguishable alleles ranging from 109bp to 128bp and 139bp to 163bp in length, respectively. Testing for Hardy-Weinberg equilibrium (HWE) showed no significant deviation for these two loci. The polymorphism information content (PIC), observed heterozygosity (H(obs)) and power of exclusion for parentage testing of a girl for trios (PE(trio)) and duos (PE(duo)) were 0.67, 0.687, 0.673 and 0.530 for DXS6803, and 0.69, 0.736, 0.688 and 0.547 for DXS9895, respectively. Seventy-eight families studies of these two loci confirmed X-linked codominant inheritance and mutations were not found.

Development of models to predict anabolic response to testosterone administration in healthy young men

Considerable heterogeneity exists in the anabolic response to androgen administration; however, the factors that contribute to variation in an individual's anabolic response to androgens remain unknown. We investigated whether testosterone dose and/or any combination of baseline variables, including concentrations of hormones, age, body composition, muscle function, and morphometry or polymorphisms in androgen receptor could explain the variability in anabolic response to testosterone. Fifty-four young men were treated with a long-acting gonadotropin-releasing hormone (GnRH) agonist and one of five doses (25, 50, 125, 300, or 600 mg/wk) of testosterone enanthate (TE) for 20 wk. Anabolic response was defined as a change in whole body fat-free mass (FFM) by dual-energy X-ray absorptiometry (DEXA), appendicular FFM (by DEXA), and thigh muscle volume (by magnetic resonance imaging) during TE treatment. We used univariate and multivariate analysis to identify the subset of baseline measures that best explained the variability in anabolic response to testosterone supplementation. The three-variable model of TE dose, age, and baseline prostate-specific antigen (PSA) level explained 67% of the variance in change in whole body FFM. Change in appendicular FFM was best explained (64% of the variance) by the linear combination of TE dose, baseline PSA, and leg press strength, whereas TE dose, log of the ratio of luteinizing hormone to testosterone concentration, and age explained 66% of the variation in change in thigh muscle volume. The models were further validated by using Ridge analysis and cross-validation in data subsets. Only the model using testosterone dose, age, and PSA was a consistent predictor of change in FFM in subset analyses. The length of CAG tract was only a weak predictor of change in thigh muscle volume and lean body mass. Hence, the anabolic response of healthy, young men to exogenous testosterone administration can largely be predicted by the testosterone dose.

Use of X-linked markers for forensic purposes

In forensic science, X-chromosomal short tandem repeats (ChrX STRs) bear the potential to efficiently complement the analysis of other genetic markers (autosomal, Y-chromosomal or mitochondrial). We review the population genetic properties and forensic utility of selected ChrX markers, and discuss the problems and limitations arising with their practical use. Formulae required to assess the evidential power of individual markers in different contexts are summarised and applied to ChrX STRs of interest. Since linkage and linkage disequilibrium between markers affect the inferential interpretation of genotype data, practically relevant information regarding the co-localisation and haplotypic association of ChrX STRs is provided. Finally, two examples of complex kinship testing are presented which serve to highlight the particular importance of ChrX STRs for solving deficiency cases and cases involving blood relatives.

Linkage disequilibrium between the androgen receptor gene CAG and GGC repeats in the African-American population

African-American men are at an increased risk of developing prostate cancer when compared with other racial and ethnic groups. In addition, African-Americans display a greater propensity for developing aggressive prostate cancer. There are multiple etiologic factors that likely contribute to the development of prostate cancer; however, one potential factor that may explain differences of prostate cancer risk among ethnic and racial groups is the androgen receptor (AR) gene. Studies have showed that there is correlation between two polymorphic microsatellite regions of the AR receptor gene and its transactivational activity. The CAG and GGC repeats both have been implicated as important loci for variation in differential androgen receptor activity. This review analyzes the available data regarding variation of the CAG and GGC repeat sequences among different racial and ethnic populations, and the implications of these variations for prostate cancer risk.

Validation of the STR DXS7424 and the linkage situation on the X-chromosome

X-linked microsatellite markers have proven to be powerful tools for parentage testing, mainly in deficiency paternity cases when the disputed child is female. However, only a small number of X-linked short tandem repeats (STRs) have been comprehensively described for forensic applications to date. We present sequence and population genetic data of the DXS7424 STR (GDB-G00-577-633) which is a trinucleotide repeat polymorphism representing 12 alleles of 147-180 bp in length. DXS7424 is located at Xq22 and closely linked to DXS101, corresponding to a genetic localisation of 104.9-121 cM from Xp-tel.PCR fragment length measurements and sequencing were carried out using the automatic gene analyser ABI 310 (Applied Biosystems). The population of 764 unrelated Germans checked for this STR exhibited the following features: polymorphism information content (PIC) = 0.780; heterozygosity (Het) = 0.843; mean exclusion chance (MEC = 0.766. Kinship tests revealed a typical X-linked inheritance. In 300 meioses under investigation, mutations were not found. Significant deviations from the Hardy-Weinberg equilibrium (HWE) were not established. Linkage studies confirmed closely linkage to DXS101. Additional we found linkage disequilibrium between DXS7424 and DXS101. This requires to use the established haplotype frequencies in kinship testing.

Malignant mesenchymoma of the uterus, arising in a leiomyoma

AIMS

To document and find evidence for the rare occurrence of malignant progression of a benign uterine leiomyoma with divergent mesenchymal differentiation. In a 54-year-old female a large pedunculated tumour was encountered which had suddenly increased in size and had apparently arisen at the site of a subserosal uterine leiomyoma first described 19 years earlier. The tumour seemed histologically diverse in its composition. The possibility of malignant progression of the benign leiomyoma with divergent mesenchymal differentiation was entertained.

METHODS AND RESULTS

In the resected tumour, smooth muscle, osseous and adipose components were identified and these were assessed using recognized histological criteria of malignancy. In addition to a benign smooth muscle component, malignant leiomyosarcomatous tissue was seen in addition to a malignant osseous component and a malignant adipose component. The tumour thus met the criteria of a malignant mesenchymoma. The relationship of the different components of the tumour was analysed by immunohistochemistry and with molecular loss of heterozygosity (LOH) analysis. In the osseous and leiomyosarcomatous components a similar LOH pattern was observed. The adipose component showed a distinct LOH pattern. Retention of smooth muscle differentiation in the osseous component was demonstrated by desmin immunostaining.

CONCLUSION

Malignant transformation of benign uterine leiomyoma may rarely occur. Mesenchymal stem cells underlying these tumours may show divergent mesenchymal differentiation.

Contribution of the microvessel network to the clonal and kinetic profiles of adrenal cortical proliferative lesions

Monoclonal adrenocortical lesions have been characterized by an inverse correlation between proliferation and apoptosis, and polyclonal lesions show a direct correlation. Their relationship with the vascular pattern remains unknown in adrenocortical nodular hyperplasias (ACNHs), adenomas (ACAs), and carcinomas (ACCs). We studied 20 ACNHs, 25 ACAs, and 10 ACCs (World Health Organization classification criteria) from 55 women. The analysis included X-chromosome inactivation assay (on microdissected samples), slide and flow cytometry, and in situ end labeling. Endothelial cells were stained with anti-CD31, and the blood vessel area and density were quantified by image analysis in the same areas. Appropriate tissue controls were run in every case. Regression analyses between kinetic and vascular features were performed in both polyclonal and monoclonal lesions. Polyclonal patterns were observed in 14 of 18 informative ACNHs and 3 of 22 informative ACAs, and monoclonal patterns were seen in 4 of 18 ACNHs, 19 of 22 ACAs, and 9 of 9 ACCs. A progressive increase in microvessel area was observed in the ACNH-ACA-ACC transition but was statistically significant between benign and malignant lesions only (191.36 +/- 168.32 v 958.07 +/- 1279.86 microm(2); P < .0001). In addition, case stratification by clonal pattern showed significant differences between polyclonal and monoclonal benign lesions; 6% of polyclonal and 57% of monoclonal lesions had microvessel area >186 microm(2) (P = .0000008). Monoclonal lesions showed parallel trends (but with opposite signs) for microvessel area and density in comparison with proliferation and apoptosis, whereas polyclonal lesions showed inverse trends. In conclusion, the kinetic advantage of monoclonal adrenal cortical lesions (increased proliferation, decreased apoptosis) is maintained by parallel increases in microvessel area and density.

Lack of influence of the androgen receptor gene CAG-repeat polymorphism on sex steroid status and bone metabolism in elderly men

OBJECTIVE

Population means for serum testosterone (T) levels in healthy men decrease with ageing but there is considerable interindividual variability of serum T in elderly men. Ultimate androgen action is mediated through the androgen receptor. Subtle differences in androgen sensitivity might contribute to serum T variability through the T negative feedback regulation. The androgen receptor gene (AR) contains in exon 1 a polymorphic trinucleotide CAG-repeat, whose length modulates androgen receptor action. The aims of the study were to assess the potential contribution of the AR CAG-repeat polymorphism in the interindividual variability of serum T and in the determination of bone metabolism in ambulatory elderly men.

DESIGN AND PATIENTS

We used cross-sectional baseline data of a longitudinal study investigating the process of ageing, in particular the changes in hormonal status and bone metabolism, in a cohort of 273 community-dwelling healthy men, between age 71 and 86 years.

MEASUREMENTS

AR CAG-repeat length was determined by automated DNA sequencing of exon 1 of the AR gene. Serum T, sex hormone binding globulin, LH and oestradiol were measured by specific immunoassays. Bone mineral density (BMD) was determined by dual energy X-ray absorptiometry. Bone turnover was assessed by measurement of serum bone-specific alkaline phosphatase, serum osteocalcin, serum C-terminal type I procollagen peptide, serum and urinary C-terminal telopeptides of type I collagen and urinary deoxypyridinoline levels, with use of immunoassays.

RESULTS

No significant association was found between the AR CAG-repeat length and either total or free T, LH or the androgen sensitivity index (LHxT). BMD measurements at the hip and the forearm were not associated with AR CAG-repeat length and there was no association of this AR polymorphism with any of the biochemical markers of bone turnover. Results were not different after adjustments for age and body mass index.

CONCLUSIONS

The findings of the present study do not support the view that in community-dwelling, healthy elderly men the androgen receptor gene CAG-repeat polymorphism has a substantial impact on interindividual variability of serum testosterone levels or on the determination of bone turnover and bone mineral density.

Lack of association between androgen receptor CAG polymorphism and familial breast/ovarian cancer

The human androgen receptor (AR) gene contains a highly polymorphic CAG repeat in exon 1 that is inversely correlated with AR transcriptional activity in vitro. Several studies have shown that fewer CAG repeats are associated with an increased risk as well as more aggressive forms of prostate cancer. More recently, AR allele length was also inversely correlated with the histological grade of breast cancer, but no association was found between the AR-CAG polymorphism and the risk of either breast or ovary cancer. On the contrary, it was proposed that a longer CAG repeat sequence might be associated with an increased risk of breast cancer in BRCA1 mutation carriers, thus suggesting a different role of the AR-CAG polymorphism in sporadic and inherited breast cancers. With the intent of better understanding the role of the AR-CAG polymorphism as a cancer risk modifier, we defined the AR genotype of 151 patients (101 with breast and 50 with ovary cancer) belonging to high-risk breast/ovary cancer families. No difference in CAG repeat length was found between either breast and ovary cancer patients or age at diagnosis of both tumors. These results were also confirmed in a sub-group of 47 breast cancer cases, that either carried a BRCA gene mutation (11 cases) or were identified by very stringent operational criteria as hereditary breast cancers. Even though a substantially larger sample size would be required to reach conclusive evidence, our findings suggest that the AR-CAG polymorphism does not act as a modifier of tumor onset or tumor phenotype in breast/ovarian cancer families.

Development of the X-linked tetrameric microsatellite marker HumDXS6789 for forensic purposes

This paper presents sequence and population genetic data of the X-linked DXS6789 short tandem repeat (STR). The tetranucleotide repeat polymorphism DXS6789, also known as CHLC.GATA31F01, is located at the Xq22.3 region. This locus is unlinked with DXS6807 and slightly linked with ARA, DXS9898 and HPRTB. In kinship testing, DXS6789 is suitable for concomitant use with DXS6807. Population genetic data were obtained by analysing 250 unrelated males and 315 females from East Germany. In this population, the STR exhibited 12 clearly distinguishable alleles ranging from 154 to 198bps in length. DXS6789 is characterised by the following data: polymorphic information content (PIC)=0.70; observed heterozygosity (Het)=0.78; mean exclusion chance (MEC)=0.70. A deviation from the Hardy-Weinberg equilibrium could not be detected. The investigations we performed in 243 mother-child and 161 father-child meioses did not reveal any mutations.

CAG and GGC repeat polymorphisms in the androgen receptor gene and breast cancer susceptibility in BRCA1/2 carriers and non-carriers

Variation in the penetrance estimates for BRCA1 and BRCA2 mutations carriers suggests that other genetic polymorphisms may modify the cancer risk in carriers. A previous study has suggested that BRCA1 carriers with longer lengths of the CAG repeat in the androgen receptor (AR) gene are at increased risk of breast cancer (BC). We genotyped 188 BRCA1/2 carriers (122 affected and 66 unaffected with breast cancer), 158 of them of Ashkenazi origin, 166 BC cases without BRCA1/2 mutations and 156 Ashkenazi control individuals aged over 56 for the AR CAG and GGC repeats. In carriers, risk analyses were conducted using a variant of the log-rank test, assuming two sets of risk estimates in carriers: penetrance estimates based on the Breast Cancer Linkage Consortium (BCLC) studies of multiple case families, and lower estimates as suggested by population-based studies. We found no association of the CAG and GGC repeats with BC risk in either BRCA1/2 carriers or in the general population. Assuming BRCA1/2 penetrance estimates appropriate to the Ashkenazi population, the estimated RR per repeat adjusted for ethnic group (Ashkenazi and non-Ashkenazi) was 1.05 (95%CI 0.97-1.17) for BC and 1.00 (95%CI 0.83-1.20) for ovarian cancer (OC) for CAG repeats and 0.96 (95%CI 0.80-1.15) and 0.90 (95%CI 0.60-1.22) respectively for GGC repeats. The corresponding RR estimates for the unselected case-control series were 1.00 (95%CI 0.91-1.10) for the CAG and 1.05 (95%CI 0.90-1.22) for the GGC repeats. The estimated relative risk of BC in carriers associated with > or =28 CAG repeats was 1.08 (95%CI 0.45-2.61). Furthermore, no significant association was found if attention was restricted to the Ashkenazi carriers, or only to BRCA1 or BRCA2 carriers. We conclude that, in contrast to previous observations, if there is any effect of the AR repeat length on BRCA1 penetrance, it is likely to be weak.

Molecular basis of androgen insensitivity

Androgens are important steroid hormones for expression of the male phenotype. They have characteristic roles during male sexual differentiation, during development and maintenance of secondary male characteristics, and during the initiation and maintenance of spermatogenesis. The two most important androgens in this respect are testosterone and 5 alpha-dihydrotestosterone. Each androgen has its own specific role during male sexual differentiation, testosterone is involved in the development and differentiation of Wolffian duct derived structures, whereas 5 alpha-dihydrotestosterone, a metabolite of testosterone, is the active ligand in the urogenital sinus and tubercle and their derived structures. The actions of androgens are mediated by the androgen receptor. This ligand dependent transcription factor belongs to the superfamily of nuclear receptors, including those for the other steroid hormones. The androgen receptor gene is located on the X-chromosome at Xq11--12 and codes for a protein with a molecular mass of approximately 110 kDa. Only one androgen receptor cDNA has been identified sofar, despite two different ligands. It is generally accepted that defects in the androgen receptor gene prevent the normal development of both internal and external male structures in 46, XY individuals. The end-organ resistance to androgens has been designated as androgen insensitivity syndrome (AIS) and is distinct from other forms of male pseudohermaphroditism like 17 beta-hydroxy-steroid dehydrogenase type 3 deficiency, leydig cell hypoplasia due to inactivating LH receptor mutations or 5 alpha-reductase type 2 deficiency. Furthermore, two additional pathological situations are associated with abnormal androgen receptor structure and function -- spinal and bulbar muscular atrophy (SBMA, or Kennedy's disease) and prostate cancer. In the AR gene, four different types of mutations have been detected in DNA from individuals with AIS -- (i) single point mutations resulting in amino acid substitutions or premature stopcodons; (ii) nucleotide insertions or deletions most often leading to a frame shift and premature termination; (iii) complete or partial gene deletions; and (iv) intronic mutations in either splice donor or acceptor sites, which affect the splicing of AR RNA. The main phenotypic characteristics of individuals with the complete androgen insensitivity syndrome (CAIS) are, female external genitalia, a short, blind ending vagina, the absence of Wolffian duct derived structures, the absence of a prostate, development of gynecomastia and the absence of pubic and axillary hair. Usually testosterone levels are elevated at the time of puberty, while also elevated LH levels are found. In the partial androgen insensitivity syndrome (PAIS) several different phenotypes are evident, ranging from individuals with predominantly a female appearance to persons with ambiguous genitalia, or individuals with a predominantly male phenotype. At puberty, elevated LH, testosterone and estradiol levels are observed. Individuals with mild symptoms of undervirilization (mild androgen insensitivity syndrome (MAIS)) and infertility have been described as well. Phenotypic variation between individuals in different families has been described for several mutations. However, in cases of CAIS no phenotypic variation has been described within one single family, in contrast to families with individuals with PAIS. In general AIS, can be routinely analyzed and more than 150 different mutations have been reported now. Differential diagnosis of AIS is possible with syndromes presenting with almost similar phenotypes but with a completely different molecular cause.

Clinical and molecular genetics of ADHD and Tourette syndrome. Two related polygenic disorders

ADHD is a polygenic disorder due to the additive effect of genes affecting dopamine, norepinephrine, serotonin, GABA, and other neurotransmitters. Some of the specific loci involved are dopamine genes--DRD2, DRD4, DRD5, and the dopamine transporter; norepinephrine (NE) and epinephrine (EPI) genes--dopamine beta-hydroxylase, ADRA2A, ADRA2C, PNMT, norepinephrine transporter, MAOA, COMT; serotonin genes--TDO2, HTR1A, HTR1DA, serotonin transporter; GABA genes--GABRB3; androgen receptor and other genes. This model is consistent with all of the present knowledge about ADHD including (a) the increased frequency of ADHD in the relatives of ADHD probands, (b) the presence of a wide spectrum of comorbid behaviors (depression, anxiety, learning, conduct, oppositional-defiant, conduct and substance abuse disorders) in ADHD probands and their relatives on both parental sides, (c) the close relationship to Tourette syndrome (TS), (d) the failure to find the genes for TS using linkage analysis, (e) the brain imaging studies showing hypometabolism of the frontal lobes, (f) the relationship between dopamine D2 receptor density and regional blood flow, (g) the correlation between tics and dopamine D2 receptor density in TS, (h) the motor hyperactivity of dopamine transporter and dopamine D3 receptor gene knockout mice, (i) the LeMoal and Shaywitz dopamine deficiency animal models of ADHD, (j) the NE models of ADHD, (k) the failure to explain ADHD on the basis of any single neurotransmitter defect, (l) the response of ADHD to dopamine and alpha 2-adrenergic agonists, (m) the small percentage of the variance of specific behaviors accounted for by each gene, and numerous other aspects of ADHD. The implications of the polygenic model for the understanding, diagnosis and treatment of ADHD and TS, as well as other psychiatric disorders, are reviewed.

PCR techniques for clonality assays

Clonal overgrowths represent the hallmark of neoplastic proliferations, and their demonstration has been proved useful clinically for the diagnosis of malignant lymphomas based on the detection of specific and dominant immunoglobulin and/or T-cell receptor gene rearrangements. Nonrandom genetic alterations can also be used to test clonal expansions and the clonal evolution of neoplasms, especially analyzing hypervariable deoxyribonucleic acid (DNA) regions from patients heterozygous for a given marker. These tests rely basically on the demonstration of loss of heterozygosity (LOH) resulting from either hemizygosity (nonrandom interstitial DNA deletions) or homozygosity of mutant alleles observed in neoplasms. LOH analyses identify clonal expansions of a tumor cell population, and point to monoclonal proliferation when multiple and consistent LOH are demonstrated. Based on the methylation-related inactivation of one X chromosome in female subjects, X-linked markers (e.g., androgen receptor gene) will provide clonality information using LOH analyses after DNA digestion with methylation-sensitive restriction endonucleases. Therefore, both non-X-linked and X-linked analyses give complementary information, related and not related to the malignant transformation pathway respectively. Applied appropriately, these tools can establish the clonal evolution of tumor cell populations (tumor heterogeneity), identify early relapses, distinguish recurrent tumors from other metachronic neoplasms, and differentiate field transformation from metastatic tumor growths in synchronic and histologically identical neoplasms.

A multivariate analysis of 59 candidate genes in personality traits: the temperament and character inventory

Cloninger (Cloninger CR. Neurogenetic adaptive mechanisms in alcoholism. Science 1987: 236: 410-416) proposed three basic personality dimensions for temperament: novelty seeking, harm avoidance, and reward dependence. He suggested that novelty seeking primarily utilized dopamine pathways, harm avoidance utilized serotonin pathways, and reward dependence utilized norepinephrine pathways. Subsequently, one additional temperament dimension (persistence) and three character dimensions (cooperativeness, self-directedness, and self-transcendence) were added to form the temperament and character inventory (TCI). We have utilized a previously described multivariate analysis technique (Comings DE, Gade-Andavolu R, Gonzalez N et al. Comparison of the role of dopamine, serotonin, and noradrenergic genes in ADHD, ODD and conduct disorder. Multivariate regression analysis of 20 genes. Clin Genet 2000: 57: 178-196; Comings DD, Gade-Andavolu R, Gonzalez N et al. Multivariate analysis of associations of 42 genes in ADHD, ODD and conduct disorder. Clin Genet 2000: in press) to examine the relative role of 59 candidate genes in the seven TCI traits and test the hypothesis that specific personality traits were associated with specific genes. While there was some tendency for this to be true, a more important trend was the involvement of different ratios of functionally related groups of genes, and of different genotypes of the same genes, for different traits.

Identification and characterization of an Xq26-q27 duplication in a family with spina bifida and panhypopituitarism suggests the involvement of two distinct genes

We investigated a family with a duplication, dup(X)q26-q27, that was present in two brothers, their mother, and their maternal grandmother. The brothers carrying the duplication displayed spina bifida and panhypopituitarism, whereas a third healthy brother inherited the normal X chromosome. Preferential inactivation of the X chromosome containing the duplication was evident in healthy carrier females. We determined the boundaries of the Xq26-q27 duplication. Via interphase FISH analysis we narrowed down each of the two breakpoint regions to approximately 300-kb intervals. The proximal breakpoint is located in Xq26.1 between DXS1114 and HPRT and is contained in YAC yWXD599, while the distal breakpoint is located in Xq27.3 between DXS369 and DXS1200 and contained in YAC yWXD758. The duplication comprises about 13 Mb. Evidence from the literature points to a predisposing gene for spina bifida in Xq27. We hypothesize that the spina bifida in the two brothers may be due to interruption of a critical gene in the Xq27 breakpoint region. Several candidate genes were mapped to the Xq27 critical region but none was shown to be disrupted by the duplication event. Recently, M. Lagerström-Fermér et al. (1997, Am. J. Hum. Genet. 60, 910-916) reported on a family with X-linked recessive panhypopituitarism associated with a duplication in Xq26; however, no details were reported on the extent of the duplication. Our study corroborates their hypothesis that X-linked recessive panhypopituitarism is likely to be caused by a gene encoding a dosage-sensitive protein involved in pituitary development. We place the putative gene between DXS1114 and DXS1200, corresponding to the interval defined by the duplication in the present family.

Inactivation of the human androgen receptor gene is associated with CpG hypermethylation in uterine endometrial cancer

Androgens mediate their effects through the androgen receptor (AR) and have antiproliferative effects on uterine endometrial cells. In this report, we investigated methylation status and the expression of the AR gene in normal endometrium and uterine endometrial cancer (UEC) tissues using methylation-specific polymerase chain reaction (MSP) and immunohistochemical staining. Seventy of 89 cancer samples were AR negative, although 39 of 46 normal samples were AR positive by immunohistochemistry. By MSP, 64 of 89 cancer samples showed only methylated AR alleles, although all normal tissues showed both unmethylated and methylated AR alleles. To determine whether similar changes occurred in methylation status in the UEC carcinogenesis, we studied AR methylation using pairs of cancerous and normal samples from 28 patients. Twenty-three of 28 cancer samples showed only methylated AR alleles, although all normal samples showed both unmethylated and methylated alleles. All of the 23 cancer samples that lost unmethylated alleles were negative for AR by immunohistochemical analysis. Reverse transcription-polymerase chain reaction was performed by using UEC cell lines with and without treatment by the demethylating reagent 5-aza-2'-deoxycytidine. No AR expression was found in any of the UEC cell lines, except for MFE-296 without 5-aza-2'-deoxycytidine. Treatment with 5-aza-2'-deoxycytidine restored AR expression in all of the UEC cell lines that showed no AR expression before treatment. This study is the first to report that the possible mechanism of AR inactivation in endometrial cancer is through hypermethylation of the AR gene CpG islands.

Clonality as expression of distinctive cell kinetics patterns in nodular hyperplasias and adenomas of the adrenal cortex

Although histopathologic criteria for adrenal cortical nodular hyperplasias (ACNHs) and adenomas (ACAs) have been developed, their kinetics and clonality are virtually unknown. We studied 20 ACNHs and 25 ACAs (based on World Health Organization criteria) from 45 females. Representative samples were histologically evaluated, and the methylation pattern of the androgen receptor alleles was analyzed on microdissected samples. Consecutive sections were selected for slide cytometry, flow cytometry, and in situ end labeling (ISEL). Apoptosis was studied by flow cytometry (nuclear area/DNA content plotter analysis) and by ISEL. Appropriate tissue controls were run in every case. Polyclonal gel patterns were revealed in 14/18 informative ACNHs and in 3/22 informative ACAs, whereas monoclonal gel patterns were observed in 4/18 ACNHs and 19/22 ACAs. Overlapping proliferation rates (PRs) were observed in both clonal groups, and apoptosis was detected only in G(0)/G(1) cells, especially in monoclonal ACNHs (3/4; 75%) and in polyclonal ACAs (2/3; 67%). Significantly higher PRs were observed in ACNHs with polyclonal patterns and G(0)/G(1) apoptosis and in ACAs regardless of clonality pattern and presence of G(0)/G(1) apoptosis. All except one ACNH (19/20; 95%) and 15/25 ACAs (60%) showed diploid DNA content, whereas the remaining cases were hyperdiploid. A direct correlation between PR and ISEL was observed in polyclonal lesions (PR = 29.32 ISEL - 1.93), whereas the correlation was inverse for monoclonal lesions (PR = -9.13 ISEL + 21.57). We concluded that only simultaneous down-regulated apoptosis and high proliferation result in selective kinetic advantage, dominant clone expansion, and unbalanced methylation patterns of androgen receptor alleles in ACNHs and ACAs.