Impact of CYP2D6 polymorphisms in tamoxifen adjuvant breast cancer treatment

The aim of this study is to evaluate the impact of CYP2D6 genotyping in predicting disease-free survival and toxicity in breast cancer patients treated with adjuvant tamoxifen. DNA from 91 patients was genotyped using the AmpliChip CYP450 GeneChip, Roche that facilitates the classification of individuals by testing 27 alleles. When patients were grouped into group 1 (*4/*4, *4/*41, *1/*5 and *2/*5) and group 2 (the remaining genotypes), a significant difference in disease-free survival (DFS) was observed between groups (P = 0.016). The mean DFS in group 1 was 95 months in contrast with 119 months in group 2. No significant relationship was found between the CYP2D6 genotype classification and severe, mild or no toxicity (P = 0.2). Nevertheless, severe, and mild toxicity was more frequent among poor metabolizer patients than in patients with a normal metabolizer pattern (18.8 and 43.8% vs. 10.7 and 36%, respectively). In breast cancer, patients treated with adjuvant tamoxifen, non-functional and severely impaired CYP2D6 variants are associated with a worse DFS and with a higher frequency of severe and mild toxicities. Larger studies of the CYP2D6 genotype-clinical outcomes association are needed to complement initial results.

Transcription factor-binding sites in the thymidylate synthase gene: predictors of outcome in patients with metastatic colorectal cancer treated with 5-fluorouracil and oxaliplatin?

The identification of clinical and genetic parameters to predict the outcome in advanced colorectal cancer is a key issue in the management of this disease. We ascertained whether the clinical determinants of survival defined in a large cohort of patients treated with 5-fluorouracil (5-FU) (European Organization for the Research and Treatment of Cancer, EORTC model) also apply to 109 colorectal cancer patients receiving a therapy including oxaliplatin/5-FU as their first-line treatment. Our results confirm the considerable discriminatory power of the clinical model proposed in patients treated with a combined chemotherapy regimen. With the aim of identifying additional genetic prognostic parameters, we determined whether the polymorphisms in the promoter region of the thymidylate synthase (TS) gene that modifies the number of operative binding sites of a transcription factor (USF) could predict the clinical outcome of our patients and complement the EORTC clinical model. Our results indicate that this new genetic parameter (the number of USF-binding sites) could be considered when evaluating the role of TS genotype in the efficacy of the 5-FU-based regimens. Further, confirmatory studies aimed at evaluating the effect of the number of binding sites of transcription factors for selecting 5-FU-treated patients are warranted.

UGT1A1 gene variations and irinotecan treatment in patients with metastatic colorectal cancer

SN-38 is the active metabolite of irinotecan and it is metabolised through conjugation by uridine diphosphate glucuronosyl transferase (UGT1A1). The major toxicity of irinotecan therapy is diarrhoea, which has been related to the enzymatic activity of UGT1A1. We examined the influence of the UGT1A1 gene promoter polymorphism in the toxicity profile, in the response rate and in the overall survival (OS) in 95 patients with metastatic colorectal cancer treated with an irinotecan-containing chemotherapy. Genotypes were determined by analysing the sequence of TATA box of UGT1A1 of genomic DNA from the patients. Clinical parameters and genotypes were compared by univariate and multivariate statistical methods. The more frequent adverse effects were asthenia (34 patients), diarrhoea (29 patients) and neutropenia (20 patients). Severe diarrhoea was observed in 7/10 homozygous (70%) and 15/45 heterozygous (33%) in comparison to 7/40 (17%) wild-type patients (P=0.005). These results maintained the statistical significance in logistic regression analysis (P=0.01) after adjustment for other clinical relevant variables. The presence of severe haematological toxicity increased from wild-type patients to UGT1A1(*)28 homozygotes, but without achieving statistical significance. No relationship was found between the UGT1A1(*)28 genotypes and infection, nausea or mucositis. In univariate studies, patients with the UGT1A1(*)28 polymorphism showed a trend to a poorer OS (P=0.09). In the multivariate analysis, the genotype was not related to clinical response or to OS. The role of the UGT1A1 genotype as a predictor of toxicity in cancer patients receiving irinotecan demands the performance of a randomized trial to ascertain whether genotype-adjusted dosages of the drug can help to establish safe and effective doses not only for patients with the UGT1A1(*)28 homozygous genotype but also for those with the most common UGT1A1 6/6 or 6/7 genotype.

BRCA2 mutation analysis of 87 Spanish breast/ovarian cancer families

BACKGROUND

It is estimated that about 5% -10% of breast cancer (BC) cases is due to inherited predisposition. Early works reported that 45%-50% of site-specific BC families had BRCA1 mutations and 25%-35% BRCA2 mutations. However, these percentages could have been overestimated and likely vary among the populations studied.

PATIENTS AND METHODS

We analysed the BRCA2 gene in 87 Spanish breast/ovarian cancer families in which the BRCA1 mutation screening was negative.

RESULTS

We detected 15 (17.2%) disease-causing mutations and 11 polymorphisms and unclassified variants. Four mutations were recurrent, and five were novel. Seven (47%) mutations were found in site-specific female BC families, five (33%) in families with OC cases, and three (20%) mutations in families with male BC cases. There was incomplete penetrance of the mutations in some families, and considerable phenotypic variations with respect to the age of diagnosis and cancer types.

CONCLUSIONS

The percentage of mutations detected reinforces the possibility that some of these families have mutations in genes other than BRCA1 or BRCA2 that confer lower BC risks.

Characterisation of SMN hybrid genes in Spanish SMA patients: de novo, homozygous and compound heterozygous cases

Autosomal recessive spinal muscular atrophy (SMA) is classified, by age of onset and maximal motor milestones achieved, into type I (severe form), type II (intermediate form) and type III (mild/moderate form). SMA is caused by mutations in the survival motor neuron telomeric gene (SMN1) and a centromeric functional copy of this gene (SMN2) exists, both genes being located at 5q13. Homozygous deletion of exons 7 and 8 of SMN1 has been detected in approx 85% of Spanish SMA patients regardless of their phenotype. Nineteen cases with the sole deletion of exon 7 but not exon 8 (2 cases of type I, 13 cases of type II, four cases of type III) were further analysed for the presence of SMN2-SMN1 hybrid genes. We detected four different hybrid structures. Most of the patients were carriers of a hybrid structure: centromeric intron 6- centromeric exon 7- telomeric exon 8 (CCT), with or without neuronal apoptosis-inhibitor protein (NAIP). In two patients, a different hybrid structure, viz. telomeric intron 6- centromeric exon 7- telomeric exon 8 (TCT), was detected with or without NAIP. A phenotype-genotype correlation comparing the different structures of the hybrid alleles was delineated. Type I cases in our series are attributable to intrachromosomal deletion with a smaller number of SMN2 copies. Most cases with hybrid genes are type II occurring by a combination of a classical deletion in one chromosome and a hybrid gene in the other. Type III cases are closely associated with homozygozity or compound heterozygozity for hybrid genes resulting from two conversion events and have more copies of hybrid genes and SMN2 than type I or II cases.

Telangiectasia macularis eruptiva perstans presented as a pseudoallergic food reaction

Telangiectasia macularis eruptiva perstans (TMEP) is a rare form of cutaneous mastocytosis observed in less than 1% of cases of mastocytosis. Clinically, anaphylaxis may appear as a result of increased mast cell degranulation in different circumstances. A case of TMEP presented as pseudoallergic reactions to foods is reported in which the appearance of typical lesions on the trunk and their histological analysis together with a negative food allergy study confirmed the diagnosis.

PTEN mutations in endometrial carcinomas: a molecular and clinicopathologic analysis of 38 cases

PTEN mutations have been reported to be frequent in endometrioid carinomas of the endometrium (EEC). Some correlation has been found between PTEN mutations and the presence of microsatellite instability (MI) in EEC, but no convincing cause-effect relationship for such association has been offered. DNA of 38 patients with endometrial carcinoma (EC) was extracted from blood and from fresh-frozen and paraffin-embedded tumor tissue. PTEN mutations were detected by single-strand conformation polymorphism (SSCP) analysis and DNA sequencing. Results were correlated with MI status and clinicopathologic data. PTEN mutations were detected in 17 tumors (44.7%), and they were more frequent in endometrioid (EEC) (17 of 33, 51.5%) than in nonendometrioid carcinomas (NEEC) (0 of 5, 0%). PTEN mutational spectrum differed between MI+ and MItumors. PTEN mutations were detected in 9 of 15 MI+ tumors (60%), but in only 8 of 23 MI- neoplasms (34.8%). In EC with MI, PTEN mutations were detected in short coding mononucleotide repeats (A)s and (A)6 in 4 of 9 carcinomas (44.4%). These results confirm that PTEN is an important target gene in endometrial carcinogenesis. The occurrence of PTEN mutations in short coding mononucleotide repeats in MI-positive tumors suggests that these mutations may be secondary to deficiencies in mismatch repair and gives some explanation for the frequent presence of PTEN mutations in these tumors.

Analysis of the IRBP gene as a cause of RP in 45 ARRP Spanish families. Autosomal recessive retinitis pigmentosa. Interstitial retinol binding protein. Spanish Multicentric and Multidisciplinary Group for Research into Retinitis Pigmentosa

Autosomal recessive retinitis pigmentosa (ARRP) is a degenerative disorder of photoreceptors. Mutations in several genes encoding different proteins of the visual cascade are described. The inheritance of two intragenic markers within the interstitial retinol binding protein (IRBP) gene was established in 45 Spanish families with a history of ARRP. Homozygosity mapping and cosegregation analyses were positive in 19 families. Only one heterozygous T-C transition at position 3024 (exon 1) was detected in one consanguineous family. This variant was identified as a rare polymorphism and was present in 5% of the chromosomes analyzed.

Large-cell acanthoma is a distinctive condition

We have studied the clinical and histopathologic features of 44 biopsy specimens of large-cell acanthoma (LCA) from 35 patients. There were 19 women and 16 men, 34-88 years of age (mean 75). The lesions were mainly located on the head and extremities, usually solitary, less than or equal to 10 mm in diameter, and of greater than or equal to 1 year's duration. However, there were also cases of multiple and larger lesions, and those of shorter duration. The most frequently offered clinical diagnoses were seborrheic keratosis, Bowen's disease, and LCA; two cases had the clinical features of stucco keratosis. Histologically, 41 of the specimens could be classified into three patterns: 16 lesions showed a basic pattern (mild to moderate acanthosis, hyperkeratosis, large cytoplasms and nuclei, hyperpigmentation, and bulbous rete ridges); 12 specimens showed a verrucous pattern (papillomatosis and hyperkeratosis resembling church spires); and 13 lesions exhibited a flat-hyperkeratotic pattern (compact hyperkeratosis arranged in horizontal layers of corneocytes lying on a band-like acanthotic stratum malpighii that lacks both rete ridges and papillae). Some cases exhibiting this latter pattern showed focal bowenoid changes. Some mixed and intermediate lesions demonstrated the existence of a spectrum. We have concluded that LCA is a distinctive condition with various stages of development and is probably related to stucco keratosis. It can clearly be separated histologically from solar lentigo and from solar keratosis. As other epidermal tumors, LCA can sometimes exhibit features of Bowen's disease.

DMD carrier detection in a female with mosaic Turner's syndrome

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