Considerations for radiotherapy in Bloom Syndrome: A case series.

Bloom Syndrome (BS) is a genetic DNA repair disorder, caused by mutations in the BLM gene. The clinical phenotype includes growth retardation, immunodeficiency and a strong predisposition to different types of malignancies. Treatment of malignancies in BS patients with radiotherapy or chemotherapy is believed to be associated with increased toxicity, but clinical and laboratory data are lacking. We collected clinical data of two Dutch BS patients with solid tumors. Both were treated with radiotherapy before the diagnosis BS was made and tolerated this treatment well. In addition, we collected fibroblasts from BS patients to perform in vitro clonogenic survival assays to determine radiosensitivity. BS fibroblasts showed less radiosensitivity than the severely radiosensitive Artemis fibroblasts. Moreover, studies of double strand break kinetics by counting 53BP1 foci after irradiation showed similar patterns compared to healthy controls. In combination, the clinical cases and laboratory experiments are valuable information in the discussion whether radiotherapy is absolutely contraindicated in BS, which is the Case in other DNA repair syndromes like Ataxia Telangiectasia and Artemis.

Determining the genome-wide kinship coefficient seems unhelpful in distinguishing consanguineous couples with a high versus low risk for adverse reproductive outcome.

BACKGROUND: Offspring of consanguineous couples are at increased risk of congenital disorders. The risk increases as parents are more closely related. Individuals that have the same degree of relatedness according to their pedigree, show variable genomic kinship coefficients. To investigate whether we can differentiate between couples with high- and low risk for offspring with congenital disorders, we have compared the genomic kinship coefficient of consanguineous parents with a child affected with an autosomal recessive disorder with that of consanguineous parents with only healthy children, corrected for the degree of pedigree relatedness. METHODS: 151 consanguineous couples (73 cases and 78 controls) from 10 different ethnic backgrounds were genotyped on the Affymetrix platform and passed quality control checks. After pruning SNPs in linkage disequilibrium, 57,358 SNPs remained. Kinship coefficients were calculated using three different toolsets: PLINK, King and IBDelphi, yielding five different estimates (IBDelphi, PLINK (all), PLINK (by population), King robust (all) and King homo (by population)). We performed a one-sided Mann Whitney test to investigate whether the median relative difference regarding observed and expected kinship coefficients is bigger for cases than for controls. Furthermore, we fitted a mixed effects linear model to correct for a possible population effect. RESULTS: Although the estimated degrees of genomic relatedness with the different toolsets show substantial variability, correlation measures between the different estimators demonstrated moderate to strong correlations. Controls have higher point estimates for genomic kinship coefficients. The one-sided Mann Whitney test did not show any evidence for a higher median relative difference for cases compared to controls. Neither did the regression analysis exhibit a positive association between case-control status and genomic kinship coefficient. CONCLUSIONS: In this case-control setting, in which we compared consanguineous couples corrected for degree of pedigree relatedness, a higher degree of genomic relatedness was not significantly associated with a higher likelihood of having an affected child. Further translational research should focus on which parts of the genome and which pathogenic mutations couples are sharing. Looking at relatedness coefficients by determining genome-wide SNPs does not seem to be an effective measure for prospective risk assessment in consanguineous parents.

Reproductive behavior of individuals with increased risk of having a child with retinoblastoma.

To investigate reproductive behavior of individuals at increased risk of having a child with retinoblastoma (Rb), we conducted a cross-sectional questionnaire survey among 118 counselees visiting the Clinical Genetics Department of the National Rb Center in the Netherlands. The recurrence risk for counselees ranged from <1% to 50%. The response rate was 69%. Of 43 respondents considering having children after becoming aware of their increased risk, Rb influenced reproductive behavior for 25 (58%), of whom 14 had a recurrence risk <3%. Twenty of these 25 decided against having more children and 5 used prenatal diagnosis. Eighteen of the 43 respondents did not use any of the alternative reproductive options and had children (or more children), although half indicated having had doubts about their decisions. Multiple logistic regression showed that only perceived risk (p = 0.003) was significantly associated with Rb influencing reproductive behavior. Of 17 respondents planning children (or more children), 11 (65%) considered using one of the alternative reproductive options. We conclude that reproductive behavior is greatly influenced by Rb and that perceived risk, not objective risk, is the most important factor of influence. It is important to offer individuals at increased risk continued access to genetic counseling, even when this risk is small.

Reproductive decision-making: a qualitative study among couples at increased risk of having a child with retinoblastoma.

Little is known about the reproductive decision-making process of couples with an increased risk of having a child with retinoblastoma (Rb). A qualitative study was conducted to explore the impact of prospective risk on reproductive decisions, factors influencing these decisions, and the needs of couples with regard to reproductive counselling. Fourteen couples of childbearing age who received genetic counselling between 2002 and 2006 participated in semi-structured interviews in 2008. The risk of having a child with Rb ranged from less than 1% to 50%. In most cases, the diagnosis of Rb influenced subsequent family planning. Prenatal diagnosis was used by two couples, while others refrained from having more children. Reproductive decisions were influenced by the burden of the disease for the patient and family members, the impact of ophthalmological screening under anaesthesia, and couples' perceived risk, which did not always relate to their actual risk. Reproductive choices with regard to the number of children wanted changed over time. Our findings indicate topics to be discussed during genetic counselling of couples at increased risk for a child with Rb. We suggest continued access to genetic counselling also after the initial diagnosis and treatment.

Psychosocial impact of Von Hippel-Lindau disease: levels and sources of distress.

Von Hippel-Lindau disease (VHL) is a hereditary tumor susceptibility syndrome, characterized by an increased risk of developing multiple benign and malignant tumors at various sites and ages with limited preventive options. This study evaluates the prevalence of distress among VHL family members and factors associated significantly with such distress. Forty-eight families with a VHL mutation were identified via the nine family cancer clinics in the Netherlands. In total, 171 family members (carriers, 50% at-risk, non-carriers) were approached, of whom 123 (72%) completed a self-report questionnaire. Approximately 40% of the VHL family members reported clinically relevant levels of distress, approaching 50% among the carriers and, possibly even more striking, 36% among the non-carriers. Having lost a first degree relative due to VHL during adolescence (OR 11.2; 95% CI 1.4-86.9) was related significantly to heightened levels of distress. Approximately, only one-third of those who reported heightened levels of distress had received professional psychosocial support. A substantial percentage of family members experience clinically relevant levels of distress. We would recommend the introduction of a procedure for screening for distress in this vulnerable population. Special attention should be paid to those individuals who have lost a close relative due to VHL during adolescence.

Incidence of retinoblastoma in Dutch children conceived by IVF: an expanded study.

BACKGROUND: In 2003, we reported an increased risk of retinoblastoma in children conceived by IVF between 1995 and 2002. However, population-based studies among children conceived by IVF did not find an elevated risk of retinoblastoma. METHODS: From nationwide estimates of numbers of live births conceived by IVF (n = 40 330), we estimated the expected numbers of patients with retinoblastoma conceived by IVF in the period 1995-2007. The observed number of retinoblastoma diagnoses in children conceived by IVF was obtained by questionnaires sent to the parents of children with retinoblastoma diagnosed between 1995 and 2005. For non-responders and patients diagnosed after 2005, information was available through the medical files, in which information on fertility treatment has been routinely recorded since 2000. The relative risk (RR) of retinoblastoma among children conceived by IVF was calculated for the total study period (1995-2007) and for the expanded study period (2002-2007). RESULTS: Of all eligible patients with retinoblastoma (n = 162) diagnosed in the period 1995-2007, seven were conceived by IVF. In the total study period (1995-2007) the risk was significantly elevated [RR = 2.54, 95% confidence interval (CI) = 1.02-5.23]. In the expanded study period (2002-2007), no significantly elevated risk (RR = 1.29, 95% CI = 0.16-4.66) was found. CONCLUSIONS: We found a significantly increased risk of retinoblastoma in children conceived by IVF in the total study period 1995-2007. However, this increased risk was mostly based on the much stronger risk increase observed previously, for 1995-2002. Caution and awareness on the one hand and avoiding unnecessary worries on the other hand are important at this stage of our knowledge.

Duodenal carcinoma in MUTYH-associated polyposis.

Bi-allelic germline mutations in the MUTYH gene give rise to multiple adenomas and an increased incidence of colorectal cancer. In addition, duodenal adenomas and other extra-colonic manifestations have been described in MUTYH-associated polyposis (MAP) patients. We describe two patients with bi-allelic MUTYH gene mutations with duodenal carcinoma. The tumour in Patient A was detected during evaluation of non-specific abdominal complaints. Patient B was already diagnosed with tens of adenomas and a colon carcinoma, when a duodenal neoplasm was detected. The identification of somatic G>T mutations in codon 12 of the K-RAS2 gene provides evidence that the duodenal lesions were induced by MUTYH deficiency. Studies in larger series of MAP patients are needed to investigate the risk of upper-gastro-intestinal malignancies and to determine further guidelines for endoscopical surveillance.

Genomic deletions of MSH2 and MLH1 in colorectal cancer families detected by a novel mutation detection approach.

Hereditary non-polyposis colorectal cancer is an autosomal dominant condition due to germline mutations in DNA-mismatch-repair genes, in particular MLH1, MSH2 and MSH6. Here we describe the application of a novel technique for the detection of genomic deletions in MLH1 and MSH2. This method, called multiplex ligation-dependent probe amplification, is a quantitative multiplex PCR approach to determine the relative copy number of each MLH1 and MSH2 exon. Mutation screening of genes was performed in 126 colorectal cancer families selected on the basis of clinical criteria and in addition, for a subset of families, the presence of microsatellite instability (MSI-high) in tumours. Thirty-eight germline mutations were detected in 37 (29.4%) of these kindreds, 31 of which have a predicted pathogenic effect. Among families with MSI-high tumours 65.7% harboured germline gene defects. Genomic deletions accounted for 54.8% of the pathogenic mutations. A complete deletion of the MLH1 gene was detected in two families. The multiplex ligation-dependent probe amplification approach is a rapid method for the detection of genomic deletions in MLH1 and MSH2. In addition, it reveals alterations that might escape detection using conventional diagnostic techniques. Multiplex ligation-dependent probe amplification might be considered as an early step in the molecular diagnosis of hereditary non-polyposis colorectal cancer.