Christos Yapijakis

Predictive DNA-testing for Huntington's disease and reproductive decision making: a European collaborative study

This European collaborative study addresses the question whether a predictive test result for Huntingtons disease (HD) has an effect on subsequent reproduction by comparing carriers and non-carriers of the Huntington mutation. A unique characteristic of this study is that this evaluation is done in persons at reproductive age who had a predictive test after the identification of the Huntington gene and who were counselled in one of the participating centres. Data were collected for 180 carriers and 271 non-carriers who received a predictive test result in the period 1993–1998 in Aberdeen, Athens, Cardiff, Leiden, Leuven, Paris or Rome. The mean age of the total study group was 31.5 years and for about half of the group the follow-up interval was 3 years or more, with a maximum of 7 years. The collaborative study clearly revealed an overall impact of the predictive test result on subsequent reproduction: 14% of the carriers had one or more subsequent pregnancies vs 28% of the non-carriers. In the total carrier group a prenatal test was carried out in about two thirds of the pregnancies and one child was born after preimplantation genetic diagnosis; artificial insemination by donor, egg cell donation or adoption were not reported. A more refined analysis was performed in the subgroup with a follow-up interval of at least 3 years and who reported ‘family planning’ as a motive to apply for predictive testing in the pretest period. The complexity of this motive is discussed. In this subgroup with a desire for children in the pretest period the effect of the predictive test result was more pronounced: 69% of the non-carriers had subsequent pregnancies while only 39% of the carriers who mentioned ‘family planning’ as one of the major reasons to apply for predictive testing had a subsequent pregnancy. Of the carriers with one or more subsequent pregnancies the percentage using prenatal diagnosis was slightly higher than the percentage not using it, although there were clear differences from one centre to another. The latter groups decisions may seem more intriguing but may be partially understood based on stage theories of health behaviour. Last, but not least, whatever option is chosen by a couple at increased risk of transmitting the Huntington mutation, it is of the utmost importance that professionals fully respect this decision and support the couple.

Methylenetetrahydrofolate reductase polymorphism and minor increase of risk for oral cancer

Purpose: We investigated whether the mutant methylenetetrahydrofolate reductase (MTHFR) increases risk for oral cancer. The common germ-line mutation C677T in the MTHFR gene significantly diminishes specific activity of the enzyme, which is responsible for the circulating form of folate. Folate deficiency is associated with increased risk for thrombosis, as well as for several types of cancer, through disruption of DNA methylation, DNA synthesis and deficient DNA repair. Methods: We searched for the C677T mutation by restriction fragment analysis of PCR products in DNA samples of 110 patients with oral squamous cell carcinoma and 120 healthy controls of comparable ethnicity, age and sex. Results: The number of heterozygotes was significantly different in the two groups (P<0.005), as well as in subgroups of patients with or without a positive family history for cancer, compared to normal controls (P<0.01 and P<0.005, respectively). Furthermore, the subgroup of patients with a positive family history for thrombophilia had a significant increase both in the frequencies of mutant alleles (P<0.01) and heterozygotes (P<0.001) in comparison to normal controls. Conclusions: The obtained results suggest that the MTHFR mutation is a minor contributing factor in oncogenesis in the oral region, in conjunction with low dietary uptake of folate.

Gene polymorphisms related to angiogenesis, inflammation and thrombosis that influence risk for oral cancer

Genetic association studies have implicated functional DNA polymorphisms in genes encoding factors related to angiogenesis, inflammation and thrombosis with increased risk for oral squamous cell carcinoma (OSCC). This study examines possible interactions between nine such genotype polymorphisms and their combinatory effect in assessing the OSCC risk in a European population. OSCC cases (N=162) and healthy controls (N=168) of comparable age, gender, and ethnicity (Greeks and Germans) were studied. Multivariate logistic regression models were constructed in order to assess the contribution of homozygous or heterozygous variant genotypes of polymorphisms MMP-1 (-1607 1G/2G), MMP-3 (-1171 5A/6A), MMP-9 (-1562C/T), TIMP-2 (-418C/G), VEGF (+936C/T), GPI-alpha (+807C/T), PAI-1 (4G/5G), ACE (intron 16D/I) and TAFI (+325C/T) upon overall, early and advanced stages of OSCC. Four out of nine polymorphisms affecting PAI-1, MMP-9, TIMP-2 and ACE expression contributed significantly in OSCC prediction in the various logistic regression models. Based on these findings and previous reports, possible interactions of the implicated factors leading to OSCC development, as well as an algorithm of risk estimation are discussed.

Genetic association of cytokine DNA polymorphisms with head and neck cancer

Mutations in oncogenes or tumor suppressor genes, as well as environmental factors such as tobacco chewing or smoking, poor oral hygiene, ill-fitting dental appliances, infection by certain HPV types, or alcohol abuse, seem to be involved in the multifactorial process of carcinogenesis in head and neck. Recently, several genetic association studies have indicated that common DNA polymorphisms in low penetrance genes may affect the susceptibility of an individual to malignancy. Cytokines are an important group of proteins that regulate and mediate inflammation and angiogenesis. Tumor growth, invasion and metastasis are facilitated when there is a deregulation in their production. Cytokines include interleukins (ILs), tumor necrosis factors (TNFs) and certain growth factors (GFs). A number of genetic association studies have recently investigated the putative correlation between functional DNA polymorphisms in cytokine genes and head and neck carcinomas. This review discusses the findings of such studies in oral, nasopharyngeal and esophageal squamous cell carcinomas. Extensive research has indicated that functional polymorphisms affecting gene expression of IL-4,-6,-8,-10 as well as TNF-alpha are strongly associated with increased risk for oral cancer. Gene expression of TNF-alpha seems to be associated also with esophageal carcinomas, while for nasopharyngeal cancer the picture is yet unclear. It is generally believed that such genetic association studies will gradually increase our knowledge regarding the predisposed manifestation and advancement of these malignancies in the head and neck region.

Strong association of interleukin-6 -174 G>C promoter polymorphism with increased risk of oral cancer.

In view of the recently found contribution of factors associated with thrombosis and inflammation to carcinogenesis, we investigated the possible association of interleukin-6 (IL-6) with an increased risk of oral cancer. In DNA samples of 162 patients with oral squamous cell carcinoma and 156 healthy controls of comparable ethnicity, age and sex, we studied the -174 G>C polymorphism in the IL-6 gene, which affects its transcription. C allele frequencies were significantly increased in patients compared to controls, 42.6% versus 23.1% (p<0.001). The CC homozygotes had a 7-fold greater risk of developing oral cancer (odds ratio 7.39, 95% CI 2.61-20.92), while the GC heterozygotes had a 4-fold greater risk (odds ratio 3.74, 95% CI 2.29-6.11). A significant increase in C alleles was observed in patients regardless of their smoking or alcohol consumption habits, early or advanced stage of cancer, and presence or absence of a family history for cancer or thrombophilia (p<0.001; Fishers exact test). These findings suggest that the -174 G>C polymorphism, by affecting IL-6 gene expression, is strongly associated with oral oncogenesis.

Prenatal testing for Huntington's disease: a European collaborative study.

This European study involving seven genetic centres from six countries – Aberdeen, Cardiff (UK), Leiden (Netherlands), Leuven (Belgium), Paris (France), Rome (Italy), Athens (Greece) has gathered information on prenatal testing by direct mutation analysis and exclusion testing for Huntingtons disease (HD) from the six European countries during the period 1993–1998. Data describing the parent belonging to the HD family was collected; this included their sex and age as well as their risk of developing HD. Information about previous pregnancies, the rank of the pregnancy being tested and its outcome was also gathered. In addition the number of previous prenatal tests for HD was recorded. Three hundred and five results were recorded by the participating countries between 1993 and 1998. The largest groups came from the UK (157) and the Netherlands (90). The mean age for the parent from the HD family was 30.8 years. In half of the tests the prospective parent was an asymptomatic gene carrier, 42% remained at risk, and 6% of the prospective parents were already showing clinical features of HD. 65% of tests performed used mutation analysis.

Association of angiotensin-converting enzyme gene insertion/deletion polymorphism with increased risk for oral cancer

Introduction. In light to recently found contribution of factors associated with thrombosis and inflammation to carcinogenesis, we investigated the possible association of angiotensin I- converting enzyme (ACE) with increased risk for oral cancer. Materials and methods. In DNA samples of 160 patients with oral squamous cell carcinoma and 153 healthy controls of comparable ethnicity, age and sex, we studied the insertion/deletion (I/D) polymorphism in the ACE gene, which affects its transcription. Results. The I allele frequencies were significantly increased in patients compared to controls, 40.6% versus 27.5% (p < 0.001), respectively. The II homozygotes had a three-fold greater risk for developing oral cancer (odds ratio 3.17, 95% C.I. 1.32-7.61). A significant increase of I alleles was observed in patients regardless their smoking or alcohol consumption habits, early or advanced stage of cancer, presence or absence of a family history for cancer or thrombophilia (Fischer values p < 0.05). Discussion. These findings suggest that the I/D polymorphism, by affecting the ACE gene expression, is associated with the progress of oral oncogenesis.

Prenatal diagnosis of X-linked spinal and bulbar muscular atrophy in a Greek family

X‐linked spinal and bulbar muscular atrophy (SBMA) is a late‐onset motor neuron disorder which is caused by an expansion of the trinucleotide repeat (CAG)n in the first exon of the androgen receptor gene. Two cases of prenatal testing for the disease in a Greek family are reported. An affected male died in his late 50s of this disorder and his 30‐year‐old daughter (an obligate carrier) asked for prenatal testing for SBMA. DNA analysis revealed that she indeed carried an expanded allele of 40 repeats, as well as a normal size allele of 24 repeats. Prenatal diagnosis of SBMA was performed when, on two successive pregnancies, two male fetuses with the expanded (CAG)n allele were found.

Prevalence of human papillomavirus in saliva and cervix of sexually active women

OBJECTIVE Human papillomavirus (HPV) is strongly associated with cervical cancer and possibly with some oropharyngeal cancers. However, the relation between oral and cervical HPV infection is not fully understood. This study evaluates the prevalence rate and type-concordance of HPVs in these areas. METHODS HPV DNA typing was performed in saliva and cervical specimens of 43 sexually active women, with the use of general consensus PCR and nested PCR (NPCR) tests. RESULTS The prevalence rate of HPV DNA in cervical and saliva samples was 51.2% and 11.6% with general PCR, and 60.5% and 44.2% with NPCR, respectively. The probability of HPV DNA detection with general PCR in saliva was about 8 times lower compared to the cervix (P<0.001, OR: 0.13, 95% CI: 0.04-0.37), but showed no difference when the more sensitive NPCR method was applied (P=0.139, OR: 0.52, 95% CI: 0.22-1.21). The distribution of HPV variants according to their oncogenic potential revealed no statistically significant difference, regardless to the PCR method used for both sites. All general PCR HPV DNA positive saliva specimens belonged to women with cytology findings (n=5). These women had also 8.5 times higher risk for presenting with positive HPV detection in saliva with the NPCR method (P=0.009, OR=8.50, 95% CI: 1.74-39.70). CONCLUSIONS Women with genital HPV infection are at higher risk for asymptomatic oral HPV infection. Prophylactic HPV-vaccination may reduce the burden of HPV-related diseases in both cervix and oropharynx.

Bisphosphonate-Induced Avascular Osteonecrosis of the Mandible Associated With a Common Thrombophilic Mutation in the Prothrombin Gene

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