Fertility after young-onset colorectal cancer: a study of subjects with Lynch syndrome

AIM: Infertility is a concern for young survivors of colorectal cancer (CRC), but this risk is not well quantified. Carriers of mismatch repair (MMR) mutations are a useful cohort for studying fertility after CRC as they commonly develop CRC when young, and unaffected family members provide demographically similar controls. The aim of this study was to determine the effect of CRC on fertility in a large cohort of MMR mutation carriers. METHOD: Mismatch repair mutation carriers identified from the Australasian Colorectal Cancer Family Registry were included. For each year of life within the fertile age range (15-49), the number of living individuals and the number of children born to them were determined. Individuals were grouped by whether or not they had had a diagnosis of CRC by that age. Age-specific and total fertility rates were calculated. RESULTS: We identified 1068 subjects (611 women and 457 men), of whom 467 were diagnosed with CRC. There were 1192 births during 18 674 person-years of follow-up to the women and 814 births during 14 013 person-years of follow-up to the men. The total fertility rate was decreased in women after a diagnosis of CRC compared with those who did not have CRC (1.3 vs 2.2; P = 0.0011), but age-specific fertility was only reduced in the 20-24-year age group. In men the total fertility rate was similar for both groups (2.0 vs 1.8; P = 0.27). CONCLUSION: Age-specific fertility was decreased in female CRC survivors with Lynch syndrome aged 20-24, but not in older women or in men.

Affective dysfunction in a mouse model of Rett syndrome: therapeutic effects of environmental stimulation and physical activity

Rett syndrome (RTT) is a neurodevelopmental disorder associated with mutations in the X-linked gene encoding methyl-CpG-binding protein 2 (MeCP2) and consequent dysregulation of brain maturation. Patients suffer from a range of debilitating physical symptoms, however, behavioral and emotional symptoms also severely affect their quality of life. Here, we present previously unreported and clinically relevant affective dysfunction in the female heterozygous Mecp2tm1Tam mouse model of RTT (129sv and C57BL6 mixed background). The affective dysfunction and aberrant anxiety-related behavior of the Mecp2+ / - mice were found to be reversible with environmental enrichment (EE) from 4 weeks of age. The effect of exercise alone (via wheel running) was also explored, providing the first evidence that increased voluntary physical activity in an animal model of RTT is beneficial for some phenotypes. Mecp2+ / - mutants displayed elevated corticosterone despite decreased Crh expression, demonstrating hypothalamic-pituitary-adrenal axis dysregulation. EE of Mecp2+ / - mice normalized basal serum corticosterone and hippocampal BDNF protein levels. The enrichment-induced rescue appears independent of the transcriptional regulation of the MeCP2 targets Bdnf exon 4 and Crh. These findings provide new insight into the neurodevelopmental role of MeCP2 and pathogenesis of RTT, in particular the affective dysfunction. The positive outcomes of environmental stimulation and physical exercise have implications for the development of therapies targeting the affective symptoms, as well as behavioral and cognitive dimensions, of this devastating neurodevelopmental disorder.

Lynch syndrome: natural history and colonoscopic surveillance

Lynch syndrome is the commonest inherited cause of bowel cancer. This thesis explores the natural history and cancer risk in Lynch syndrome and documents the effect of colorectal cancer on fertility. It also demonstrates that colonoscopic surveillance can prevent colorectal cancers and thus improve survival in these subjects.