Seizure 6-like (SEZ6L) gene and risk for lung cancer.

DNA pooling in combination with high-throughput sequencing was done as a part of the Sequenom-Genefinder project. In the pilot study, we tested 83,715 single nucleotide polymorphisms (SNP), located primarily in gene-based regions, to identify polymorphic susceptibility variants for lung cancer. For this pilot study, 369 male cases and 287 controls of both sexes (white Europeans of Southern German origin) were analyzed. The study identified a candidate region in 22q12.2 that contained numerous SNPs showing significant case-control differences and that coincides with a region that was shown previously to be frequently deleted in lung cancer cell lines. The candidate region overlies the seizure 6-like (SEZ6L) gene. The pilot study identified a polymorphic Met430Ile substitution in the SEZ6L gene (SNP rs663048) as the top candidate for a variant modulating risk of lung cancer. Two replication studies were conducted to assess the association of SNP rs663048 with lung cancer risk. The M. D. Anderson Cancer Center study included 289 cases and 291 controls matched for gender, age, and smoking status. The Liverpool Lung Project (a United Kingdom study) included 248 cases and 233 controls. Both replication studies showed an association of the rs663048 with lung cancer risk. The homozygotes for the variant allele had more than a 3-fold risk compared with the wild-type homozygotes [combined odds ratio (OR), 3.32; 95% confidence interval (95% CI), 1.81-7.21]. Heterozygotes also had a significantly elevated risk of lung cancer from the combined replication studies with an OR of 1.15 (95% CI, 1.04-1.59). The effect remained significant after adjusting for age, gender, and pack-years of tobacco smoke. We also compared expression of SEZ6L in normal human bronchial epithelial cells (n = 7), non-small cell lung cancer (NSCLC; n = 52), and small cell lung cancer (SCLC; n = 22) cell lines by using Affymetrix HG-U133A and HG-U133B GeneChips. We found that the average expression level of SEZ6L in NSCLC cell lines was almost two times higher and in SCLC cell lines more than six times higher when compared with normal lung epithelial cell lines. Using the National Center for Biotechnology Information Gene Expression Omnibus database, we found a approximately 2-fold elevated and statistically significant (P = 0.004) level of SEZ6L expression in tumor samples compared with normal lung tissues. In conclusion, the results of these studies representing 906 cases compared with 811 controls indicate a role of the SEZ6L Met430Ile polymorphic variant in increasing lung cancer risk.

Molecular genetic analysis of NBS1 in German melanoma patients.

The aim of this study was to investigate the role of NBS1 in the pathogenesis of malignant melanoma of the skin. To exclude the common 657del5 founder mutation, a total of 376 melanoma patients from Southern Germany were analyzed for sequence alterations in exon 6 of NBS1 by direct sequencing. Analyses revealed one 657del5 mutation and three nonsynonymous sequence variations in exon 6 of NBS1 (V210F, R215W, and F222L). Analysis of an additional sample of 629 melanoma patients and 604 controls revealed no F222L mutation, indicating that this newly identified sequence alteration is not a common polymorphism. In a case-control association study including 632 melanoma patients and 615 cancer-free control participants from Southern Germany, three publicly known single nucleotide polymorphisms located in the NBS1 gene region were analyzed. No significant associations between single nucleotide polymorphisms (rs9995, rs867185 and rs1063045) or referring calculated haplotypes and melanoma risk were identified. These results suggest that NBS1 does not play a major role in predisposition to melanoma in the Southern German population but that alterations of this gene might contribute to the risk of this cancer.

Variations in the peroxisome proliferator-activated receptor-gamma gene and melanoma risk.

There is strong evidence to suggest that the peroxisome proliferator-activated receptor (PPAR)-gamma, a member of the nuclear receptor family of transcriptional regulators, mediates tumor suppressive activities in a variety of human cancers. Recently, PPARgamma agonists were found to inhibit growth of melanoma cell lines. Here, we tested the possibility that variations in the gene encoding PPARgamma (PPARG) influence melanoma risk. Two variations of PPARG (P12A[rs1801282] and C161T [rs3856806]) were investigated in two independent case-control studies with a total of 832 melanoma patients and 790 control individuals. In the first study, homozygous carriers of the rare *T allele of the C161T polymorphism in exon 6 of PPARG were significantly more common among patients with melanoma than among healthy subjects (6.0 vs. 2.0%; P=0.0096) and this association was independent of clinical risk factors such as skin type and nevus count (odds ratio 5.18; 95% confidence interval 1.68-15.96; P=0.0041). This finding, however, could not be replicated in the second case-control study. We therefore conclude that the investigated PPARG polymorphisms are not likely to constitute a significant risk factor for the development of melanoma among German Caucasians.

Genome-wide SNP association: identification of susceptibility alleles for osteoarthritis.

The successful identification of genes involved in common human disorders is dependent upon availability of informative sample sets, validated marker panels, a high-throughput scoring technology, and a strategy for combining these resources. We have developed a universal platform based on mass spectrometry (MassARRAY) for analyzing nucleic acids with high precision and accuracy. To fuel this technology we have generated more than 100,000 validated assays for single nucleotide polymorphisms (SNPs) covering virtually all known and predicted human genes, and a large DNA sample bank from more than 50,000 consented diseased (case) and healthy (control) individuals. Taking advantage of MassARRAY's capability for quantitative analysis of nucleic acids, allele frequencies are estimated in sample pools containing large numbers of individual DNAs. Comparing frequencies between case and control pools as a first-pass filtering step is a tremendous advantage in throughput and cost over individual genotyping. We have employed this approach in numerous genome-wide association studies to identify genes implicated in common complex diseases, including osteoarthritis (OA). Access to additional patient samples through collaborations allows us to conduct replication studies that validate true disease genes. These discoveries will expand our understanding of genetic disease predisposition, and our capabilities for early diagnosis and improved therapeutic approaches.

Association of the PDCD5 locus with lung cancer risk and prognosis in smokers.

PURPOSE: Whole-genome scan association analysis was carried out to identify genetic variants predictive of lung cancer risk in smokers and to confirm the identified variants in an independent sample. PATIENTS AND METHODS: A case-control study was performed using two pools consisting of DNA from 322 German smoking lung cancer patients and 273 healthy smoking controls, respectively. A replication study was carried out using 254 Italian lung adenocarcinoma (ADCA) patients and 235 healthy controls. RESULTS: Patients with genotypes GG or CG for the rs1862214 single nucleotide polymorphism, 5' upstream of the programmed cell death 5 (PDCD5) gene, compared with those with the common genotype CC showed an increased risk of lung cancer (odds ratio, 1.6; 95% CI, 1.2 to 2.1) and a higher incidence of poor clinical stage disease (hazard ratio [HR], 1.9; 95% CI, 1.1 to 3.4; P = .023), nodal involvement (HR, 1.9; 95% CI, 1.1 to 3.6; P = .033), and short-term survivorship (HR, 1.8; 95% CI, 1.2 to 2.6, P = .003). PDCD5 mRNA expression levels were approximately 2.4-fold lower in lung ADCA as compared to normal lung tissue. Human NCI-H520 cancer cells transfected with PDCD5 cDNA showed decreased colony-forming ability. CONCLUSION: These results suggest that the rs1862214 polymorphism in PDCD5 is predictive for lung cancer risk and prognosis, and that PDCD5 may represent a novel tumor suppressor gene influencing lung cancer.

Association between a variation in LRCH1 and knee osteoarthritis: a genome-wide single-nucleotide polymorphism association study using DNA pooling.

OBJECTIVE: To perform a large-scale association analysis of single-nucleotide polymorphisms (SNPs) in patients with radiographically defined osteoarthritis (OA) of the knee. METHODS: We examined >25,000 SNPs located within approximately 14,000 genes for associations with radiographically defined knee OA, using polymerase chain reaction and MassExtend amplification techniques. Allele frequencies were estimated initially in DNA pools from 335 female patients with knee OA and 335 asymptomatic and radiographically negative female control subjects. All were of northern European ancestry. Significant allele frequency differences were validated by genotyping of individual DNA samples. Confirmed significant findings were verified in 2 additional case-control samples from the UK (443 cases and 303 controls) and Newfoundland (346 cases and 264 controls). Chondrosarcoma cell lines were used to test for potential differences in gene expression. RESULTS: The marker most strongly associated with the risk of knee OA was rs912428, a C/T polymorphism in intron 1 of LRCH1, a gene on chromosome 13q14 that encodes a novel protein of as-yet-unknown function. The frequency of the T allele compared with controls was consistently increased by 40% across all 3 case-control groups. Additional subanalyses in case-control samples with hip OA and hand OA suggested similar trends, but did not reach statistical significance. Association fine-mapping using 10 additional SNPs in LRCH1 confirmed intron 1 as the region of highest association but failed to reveal variations with significance stronger than the marker SNP, as did the haplotype analysis. LRCH1 was not up-regulated or overexpressed in chondrosarcoma cell lines exposed to inflammatory stimuli, suggesting a possible structural role. CONCLUSION: A genetic variant in LRCH1 was consistently associated with knee OA in 3 samples from 2 populations. Our results also suggest that the same association with OA may exist at other sites. Additional genetic and experimental work is needed to elucidate the precise mechanism by which the LRCH1 gene influences OA risk.

BRAF polymorphisms and risk of melanocytic neoplasia.

Somatic mutations of the BRAF gene are common in melanomas and nevi but the contribution of polymorphisms in this gene to melanoma or nevus susceptibility remains unclear. An Australian melanoma case-control sample was typed for 16 single nucleotide polymorphisms (SNP) within the BRAF gene, and five SNP in three neighboring genes. The sample comprised 755 melanoma cases from 740 families stratified by family history of melanoma and controls from 635 unselected twin families (2,239 individuals). Ancestry of the cases and controls was recorded, and the twins had undergone skin examination to assess total body nevus count, degree of freckling, and pigmentation phenotype. Genotyping was carried out via primer extension followed by matrix-assisted laser desorption ionization-time of flight mass spectrometry. SNP in the BRAF gene were found to be weakly associated with melanoma status but not with development of nevi or freckles. The estimated proportion of attributable risk of melanoma due to variants in BRAF is 1.6%. This study shows that BRAF polymorphisms predispose to melanoma but the causal variant has yet to be determined. The burden of disease associated with this variant is greater than that associated with the major melanoma susceptibility locus CDKN2A, which has an estimated attributable risk of 0.2%.

Genetic polymorphisms in DPF3 associated with risk of breast cancer and lymph node metastases.

BACKGROUND: Several studies have identified rare genetic variations responsible for many cases of familial breast cancer but their contribution to total breast cancer incidence is relatively small. More common genetic variations with low penetrance have been postulated to account for a higher proportion of the population risk of breast cancer. METHODS AND RESULTS: In an effort to identify genes that influence non-familial breast cancer risk, we tested over 25,000 single nucleotide polymorphisms (SNPs) located within approximately 14,000 genes in a large-scale case-control study in 254 German women with breast cancer and 268 age-matched women without malignant disease. We identified a marker on chromosome 14q24.3-q31.1 that was marginally associated with breast cancer status (OR = 1.5, P = 0.07). Genotypes for this SNP were also significantly associated with indicators of breast cancer severity, including presence of lymph node metastases (P = 0.006) and earlier age of onset (P = 0.01). The association with breast cancer status was replicated in two independent samples (OR = 1.35, P = 0.05). High-density association fine mapping showed that the association spanned about 80 kb of the zinc-finger gene DPF3 (also known as CERD4). One SNP in intron 1 was found to be more strongly associated with breast cancer status in all three sample collections (OR = 1.6, P = 0.003) as well as with increased lymph node metastases (P = 0.01) and tumor size (P = 0.01). CONCLUSION: Polymorphisms in the 5' region of DPF3 were associated with increased risk of breast cancer development, lymph node metastases, age of onset, and tumor size in women of European ancestry. This large-scale association study suggests that genetic variation in DPF3 contributes to breast cancer susceptibility and severity.

Role of ICAM1 in invasion of human breast cancer cells.

We identified previously a region on chromosome 19p13.2 spanning the genes encoding the intercellular adhesion molecules (ICAM), ICAM1, ICAM4 and ICAM5 as a breast cancer susceptibility locus. Genetic variants in this region were also associated with indicators of disease severity, including higher rates of metastases to other organs. Based on this association, we set out to explore the role of ICAM1 in proliferation and invasion of human breast cancer cells. We observed that ICAM1 downregulation at the mRNA and protein levels led to a strong suppression of human breast cell invasion through a matrigel matrix. Under the same conditions, no significant effect on cell proliferation in vitro was seen. Incubation of cells with an antibody against ICAM1 blocked invasion of the highly metastatic MDA-MB-435 cell line in a dose-dependent manner without affecting cell migration. We also demonstrated that the level of ICAM1 protein expression on the cell surface positively correlated with metastatic potential of five human breast cancer cell lines and that ICAM1 mRNA levels were elevated in breast tumor compared with adjacent normal tissue. These results corroborate our previous genetic finding that variations in the ICAM region are associated with the occurrence of metastases and establish a causal role of ICAM1 in invasion of metastatic human breast carcinoma cell lines.

Association between a variation in the phosphodiesterase 4D gene and bone mineral density.

BACKGROUND: Fragility fractures caused by osteoporosis are a major cause of morbidity and mortality in aging populations. Bone mineral density (BMD) is a useful surrogate marker for risk of fracture and is a highly heritable trait. The genetic variants underlying this genetic contribution are largely unknown. METHODS: We performed a large-scale association study investigating more than 25,000 single nucleotide polymorphisms (SNPs) located within 16,000 genes. Allele frequencies were estimated in contrasting DNA pools from white females selected for low (<0.87 g/cm2, n = 319) and high (> 1.11 g/cm2, n = 321) BMD at the lumbar spine. Significant findings were verified in two additional sample collections. RESULTS: Based on allele frequency differences between DNA pools and subsequent individual genotyping, one of the candidate loci indicated was the phosphodiesterase 4D (PDE4D) gene region on chromosome 5q12. We subsequently tested the marker SNP, rs1498608, in a second sample of 138 white females with low (<0.91 g/cm2) and 138 females with high (>1.04 g/cm2) lumbar spine BMD. Odds ratios were 1.5 (P = 0.035) in the original sample and 2.1 (P = 0.018) in the replication sample. Association fine mapping with 80 SNPs located within 50 kilobases of the marker SNP identified a 20 kilobase region of association containing exon 6 of PDE4D. In a second, family-based replication sample with a preponderance of females with low BMD, rs1498608 showed an opposite relationship with BMD at different sites (p = 0.00044-0.09). We also replicated the previously reported association of the Ser37Ala polymorphism in BMP2, known to interact biologically with PDE4D, with BMD. CONCLUSION: This study indicates that variants in the gene encoding PDE4D account for some of the genetic contribution to bone mineral density variation in humans. The contrasting results from different samples indicate that the effect may be context-dependent. PDE4 inhibitors have been shown to increase bone mass in normal and osteopenic mice, but up until now there have been no reports implicating any member of the PDE4 gene family in human osteoporosis.

Suppression of RAD21 gene expression decreases cell growth and enhances cytotoxicity of etoposide and bleomycin in human breast cancer cells.

A genome-wide case-control association study done in our laboratory has identified a single nucleotide polymorphism located in RAD21 as being significantly associated with breast cancer susceptibility. RAD21 is believed to function in sister chromatid alignment as part of the cohesin complex and also in double-strand break (DSB) repair. Following our initial finding, expression studies revealed a 1.25- to 2.5-fold increased expression of this gene in several human breast cancer cell lines as compared with normal breast tissue. To determine whether suppression of RAD21 expression influences cellular proliferation, RNA interference technology was used in breast cancer cell lines MCF-7 and T-47D. Proliferation of cells treated with RAD21-specific small inhibitory RNA (siRNA) was significantly reduced as compared with mock-transfected cells and cells transfected with a control siRNA (Lamin A/C). This inhibition of proliferation correlated with a significant reduction in the expression of RAD21 mRNA and with an increased level of apoptosis. Moreover, MCF-7 cell sensitivity to two DNA-damaging chemotherapeutic agents, etoposide and bleomycin, was increased after inhibition of RAD21 expression with a dose reduction factor 50 (DRF50) of 1.42 and 3.71, respectively. At the highest concentrations of etoposide and bleomycin administered, cells transfected with a single siRNA duplex targeted against RAD21 showed 57% and 60% survival as compared with control cells, respectively. Based on these findings, we conclude that RAD21 is a novel target for developing cancer therapeutics that can potentially enhance the antitumor activity of chemotherapeutic agents acting via induction of DNA damage.

Association of the NuMA region on chromosome 11q13 with breast cancer susceptibility.

The development of breast cancer is a complex process that involves multiple genes at many stages, from initial cell cycle dysregulation to disease progression. To identify genetic variations that influence this process, we conducted a large-scale association study using a collection of German cases and controls and >25,000 SNPs located within 16,000 genes. One of the loci identified was located on chromosome 11q13 [odds ratio (OR)=1.85, P=0.017]. The initial association was subsequently tested in two independent breast cancer collections. In both sample sets, the frequency of the susceptibility allele was increased in the cases (OR=1.6, P=0.01). The susceptibility allele was also associated with an increase in cancer family history (P=0.1). Fine mapping showed that the region of association extends approximately 300 kb and spans several genes, including the gene encoding the nuclear mitotic apparatus protein (NuMA). A nonsynonymous SNP (A794G) in NuMA was identified that showed a stronger association with breast cancer risk than the initial marker SNP (OR=2.8, P=0.005 initial sample; OR=2.1, P=0.002 combined). NuMA is a cell cycle-related protein essential for normal mitosis that is degraded in early apoptosis. NuMA-retinoic acid receptor alpha fusion proteins have been described in acute promyelocytic leukemia. Although the potential functional relevance of the A794G variation requires further biological validation, we conclude that variations in the NuMA gene are likely responsible for the observed increased breast cancer risk.

Large-scale association study identifies ICAM gene region as breast and prostate cancer susceptibility locus.

We conducted a large-scale association study to identify genes that influence nonfamilial breast cancer risk using a collection of German cases and matched controls and >25,000 single nucleotide polymorphisms located within 16,000 genes. One of the candidate loci identified was located on chromosome 19p13.2 [odds ratio (OR) = 1.5, P = 0.001]. The effect was substantially stronger in the subset of cases with reported family history of breast cancer (OR = 3.4, P = 0.001). The finding was subsequently replicated in two independent collections (combined OR = 1.4, P < 0.001) and was also associated with predisposition to prostate cancer in an independent sample set of prostate cancer cases and matched controls (OR = 1.4, P = 0.002). High-density single nucleotide polymorphism mapping showed that the extent of association spans 20 kb and includes the intercellular adhesion molecule genes ICAM1, ICAM4, and ICAM5. Although genetic variants in ICAM5 showed the strongest association with disease status, ICAM1 is expressed at highest levels in normal and tumor breast tissue. A variant in ICAM5 was also associated with disease progression and prognosis. Because ICAMs are suitable targets for antibodies and small molecules, these findings may not only provide diagnostic and prognostic markers but also new therapeutic opportunities in breast and prostate cancer.

Large-scale validation of single nucleotide polymorphisms in gene regions.

Genome-wide association studies using large numbers of bi-allelic single nucleotide polymorphisms (SNPs) have been proposed as a potentially powerful method for identifying genes involved in common diseases. To assemble a SNP collection appropriate for large-scale association, we designed assays for 226,099 publicly available SNPs located primarily within known and predicted gene regions. Allele frequencies were estimated in a sample of 92 CEPH Caucasians using chip-based MALDI-TOF mass spectrometry with pooled DNA. Of the 204,200 designed assays that were functional, 125,799 SNPs were determined to be polymorphic (minor allele frequency > 0.02), of which 101,729 map uniquely to the human genome. Many of the commonly available RefSNP annotations were predictive of polymorphic status and could be used to improve the selection of SNPs from the public domain for genetic research. The set of uniquely mapping, polymorphic SNPs is located within 10 kb of 66% of known and predicted genes annotated in LocusLink, which could prove useful for large-scale disease association studies.

Mining disease susceptibility genes through SNP analyses and expression profiling using MALDI-TOF mass spectrometry.

To find genes that underlie disease susceptibilities, genome-wide single nucleotide polymorphisms (SNPs) have been analyzed using high-throughput matrix assisted laser desorption/ionization (MALDI) time-of-flight (TOF) mass spectrometry (MS). As a proof-of-concept for this approach, gene regions have been identified that were previously associated by others with certain diseases or traits. On the same technology platform, accurate and absolute transcriptional profiling can be performed and applied to allele expression analysis. Here, we provide a brief review of the technology and its applications to disease gene discovery.

Designing isoform-specific peptide disruptors of protein kinase A localization.

A kinase-anchoring proteins (AKAPs) coordinate cAMP-mediated signaling by binding and localizing cAMP-dependent protein kinase (PKA), using an amphipathic helical docking motif. Peptide disruptors of PKA localization that mimic this helix have been used successfully to assess the involvement of PKA in specific signaling pathways. However, these peptides were developed as disruptors for the type II regulatory subunit (RII) even though both RI and RII isoforms can bind to AKAPs and have discrete functions. To evaluate the effects of each localized isoform, we designed peptides that specifically bind to either RI or RII. Using a peptide array, we have defined the minimal binding sequence of dual specific-AKAP 2 (d-AKAP2), which binds tightly to both RI and RII. Side-chain requirements for affinity and isoform specificity were evaluated by using a peptide substitution array where each position along the A kinase binding domain of d-AKAP2 was substituted by the other 19 l-amino acids. This array comprises 513 single-site substitution analogs of the d-AKAP2 sequence. Peptides containing single and multiple mutations were evaluated in a quantitative fluorescence binding assay and a cell-based colocalization assay. This strategy has allowed us to design peptides with high affinity (K(D) = 1-2 nM) and high specificity for RIalpha versus RIIalpha. These isoform-specific peptides will be invaluable tools to evaluate functional differences between localized RI and RII PKA and are RIalpha-specific disruptors. This array-based analysis also provides a foundation for biophysical analysis of this docking motif.

Amino acid variant in the kinase binding domain of dual-specific A kinase-anchoring protein 2: a disease susceptibility polymorphism.

The focus of human genetics in recent years has shifted toward identifying genes that are involved in the development of common diseases such as cancer, diabetes, cardiovascular diseases, and Alzheimer's disease. Because many complex diseases are late-onset, the frequencies of disease susceptibility alleles are expected to decrease in the healthy elderly individuals of the population at large because of their contribution to disease morbidity andor mortality. To test this assumption, we compared allele frequencies of 6,500 single-nucleotide polymorphisms (SNPs) located in approximately 5,000 genes between DNA pools of age-stratified healthy, European-American individuals. A SNP that results in an amino acid change from Ile to Val in the dual-specific A kinase-anchoring protein 2 (d-AKAP2) gene, showed the strongest correlation with age. Subsequent analysis of an independent sample indicated that the Val variant was associated with a statistically significant decrease in the length of the electrocardiogram PR interval. The IleVal SNP is located in the A-kinase-binding domain. An in vitro binding assay revealed that the Ile variant bound approximately 3-fold weaker to the protein kinase A (PKA)-RIalpha isoform than the Val variant. This decreased affinity resulted in alterations in the subcellular distribution of the recombinantly expressed PKA-RIalpha isoform. Our study suggests that alterations in PKA-RIalpha subcellular localization caused by variation in d-AKAP2 may have a negative health prognosis in the aging population, which may be related to cardiac dysfunction. Age-stratified samples appear to be useful for screening SNPs to identify functional gene variants that have an impact on health.

Association testing by DNA pooling: an effective initial screen.

With an ever-increasing resource of validated single-nucleotide polymorphisms (SNPs), the limiting factors in genome-wide association analysis have become genotyping capacity and the availability of DNA. We provide a proof of concept of the use of pooled DNA as a means of efficiently screening SNPs and prioritizing them for further study. This approach reduces the final number of SNPs that undergo full, sample-by-sample genotyping as well as the quantity of DNA used overall. We have examined 15 SNPs in the cholesteryl ester transfer protein (CETP) gene, a gene previously demonstrated to be associated with serum high-density lipoprotein cholesterol levels. The SNPs were amplified in two pools of DNA derived from groups of individuals with extremely high and extremely low serum high-density lipoprotein cholesterol levels, respectively. P values <0.05 were obtained for 14 SNPs, supporting the described association. Genotyping of the individual samples showed that the average margin of error in frequency estimate was approximately 4% when pools were used. These findings clearly demonstrate the potential of pooling techniques and their associated technologies as an initial screen in the search for genetic associations.

Symptoms in carriers of adrenoleukodystrophy relate to skewed X inactivation.

Skewing of X inactivation may contribute to the manifestation of symptoms in adrenoleukodystrophy carriers. We observed highly skewed X inactivation in 32% of 22 symptomatic and asymptomatic carriers but not in 7 related and 35 unrelated controls. Skewing of X inactivation correlated with clinical neurological scores but not with the extent of very long-chain fatty acid accumulation. Transcript analysis in cultured fibroblasts revealed that skewing could occur both in favor of the mutant and the wild-type allele. Adrenoleukodystrophy carriers are more susceptible to develop skewing of X inactivation in favor of the mutant allele being associated with the manifestation of symptoms.