Non-carrier Controls Research Articles

Abnormal blood pressure response to exercise occurs more frequently in hypertrophic cardiomyopathy patients with the R92W troponin T mutation than in those with myosin mutations

Abnormal blood pressure response to exercise is reported to occur in up to a third of hypertrophic cardiomyopathy (HCM) cases and is associated with an increased risk of death, particularly in the young, but it is not known whether the HCM-causing mutation influences blood pressure response to exercise. The purpose of this article is to ascertain whether the blood pressure response to exercise differs among carriers of the R92W mutation in the cardiac troponin T gene (TNNT2), which has been associated with an increased risk of sudden cardiac death in young males; carriers of mutations in the cardiac β-myosin heavy chain gene (MYH7); and their noncarrier relatives. Thirty R92WTNNT2 carriers, 51 MYH7 mutation carriers, and 68 of their noncarrier relatives were subjected to bicycle ergonometric exercise testing to assess blood pressure response to, as well as heart rate recovery after, exercise. Additional echocardiographic and demographic details were documented for all participants. R92WTNNT2 carriers demonstrated significantly more abnormal blood pressure responses to exercise (P = .021; odds ratio 3.03; confidence interval 1.13–8.12) and smaller increases in systolic blood pressure than MYH7 mutation carriers or related noncarrier control individuals. Although abnormal blood pressure response occurred at similar frequencies in males in all groups (23%–26%), the percentage of R92WTNNT2 females with abnormal blood pressure response was 64%, compared with 25% for MYH7 and 22% for noncarriers. Therefore, these results show that blood pressure response to exercise is influenced by genotype and gender in patients with HCM.

Impact of BRCA mutations on female fertility and offspring sex ratio

Positive selection for inherited mutations in breast and ovarian cancer predisposing genes, BRCA1 and BRCA2, may contribute to the high frequency of BRCA mutations among the Ashkenazi Jewish population. Impact of BRCA mutations on fertility has not been generally explored in epidemiologic studies. There are reports of distorted sex ratios in BRCA carrier families but these findings have been attributed to bias. We investigated the effect of BRCA mutations on female fertility and offspring sex ratio in a study of 260 Ashkenazi Jewish women with ovarian cancer and 331 controls, unselected for age or family history of the disease. Pregnancy success was similar for 96 mutation carrier (0.84) and 164 noncarrier cases (0.87) and controls (0.83). After adjusting for covariates, there were no significant differences between BRCA carrier and noncarrier cases and controls with regards to fertility, despite lower pregnancy rates among all cases compared to controls (P = 0.0049). Male/female sex ratios were significantly lower among offspring of carriers (0.71) than offspring of noncarriers (0.95) or those of the controls (0.99). Comparisons among the three groups yielded statistically significant distortion against males among the offspring of known and obligate BRCA carriers compared to noncarriers (OR = 0.74, 95% CI:0.55-0.99) and controls (OR = 0.71, 95% CI:0.54-0.94). In conclusion, we did not find evidence for an effect of BRCA mutations on female fertility. We found a significant excess of females among the offspring of female carriers of BRCA1 and BRCA2 mutations. Potential contribution of observed sex ratio distortions to positive selection for BRCA mutations may warrant further investigation.

Fertility in women with BRCA mutations: a case-control study

To investigate whether or not fertility is reduced in women carrying mutations in the BRCA genes (BRCA1 and BRCA2), compared with noncarrier family members. Matched case-control study. Academic. A total of 2,254 BRCA carriers and 764 noncarrier controls who were from the same families as the carriers, but tested negative for the BRCA mutation. None. History of fertility problems (yes/no) and prior use of fertility medications (yes/no) in cases and controls, obtained through administered questionnaire. There was no difference in mean parity between carriers (1.9) and noncarriers (1.9). This study, which is the first epidemiologic study to specifically investigate the effect of carrying a BRCA mutation on parity and fertility, suggests that there is likely little or no effect of the BRCA gene mutation on fertility. To our knowledge previous epidemiologic studies have not investigated the effect of carrying a BRCA mutation on parity or fertility. However, we expect that if fertility differences exist, they would be toward the limits of reproductive life, thus larger studies with age-stratified analyses are needed to definitively answer this question.

Deletions removing the last exon ofTACSTD1constitute a distinct class of mutations predisposing to Lynch syndrome

Several different genetic alterations in the etiology of Lynch syndrome (hereditary nonpolyposis colorectal cancer [HNPCC]) are known, mostly point mutations and genomic rearrangements in 1 of at least 3 mismatch-repair (MMR) genes. However, no susceptibility factor has yet been identified in a significant part (30-50%) of clinicopathologically well-defined HNPCC families, suggesting the presence of other predisposing mechanisms. In a set of probands from 27 Lynch syndrome families who lacked evidence of a germline mutation in either the MSH2 or MLH1 gene, we performed genomic deletion screening with the use of multiplex ligation-dependent probe amplification (MLPA) and sequencing. We used immunohistochemistry (IHC) and microsatellite instability (MSI) analyses on samples of the probands of all families. Comparative analysis of mRNA transcripts was performed on blood leukocyte-derived samples from mutation carriers and noncarrier controls. We report that large germline deletions encompassing the last exons of the TACSTD1 gene, upstream of MSH2, cosegregate with the HNPCC phenotype in 19% (5/27) of families tested. The tumors of the carriers show high-level MSI and MSH2 protein loss. We show that these deletions, by removing the transcriptional termination sequences of the upstream gene, give rise to multiple TACSTD1/MSH2 fusion transcripts. Our results provide evidence that deletions removing the last exon of TACSTD1 constitute a distinct class of mutations predisposing to Lynch syndrome. Thus, analysis of the 3' region of the TACSTD1 gene should be included in the routine mutation screening protocols for HNPCC.

A BRCA1 Mutation Is Not Associated with Increased Indicators of Oxidative Stress

Background Several functions have been attributed to the BRCA1 protein. A recent study suggests that BRCA1 is involved in the cellular antioxidant response by inducing the expression of genes involved in the antioxidant defense system and thus conferring resistance to oxidative stress. It is possible that individuals with a BRCA1 mutation might be susceptible to the effects of oxidative stress. The aim of this study was to evaluate whether women with a BRCA1 mutation exhibit increased indicators of oxidative stress. Patients and Methods We measured 3 markers of oxidative stress in vivo, the amounts of serum malondialdehyde and protein thiols, and 8-oxo-2′-deoxyguanosine (8-oxodG) levels in 25 unaffected BRCA1 mutation carriers and 25 noncarrier control subjects. Results There was no significant difference in serum malondialdehyde levels ( P = .41), serum thiol levels ( P = .85), or the number of 8-oxodG lesions ( P = .49) in BRCA1 mutation carriers versus noncarriers. Conclusion The results of this study suggest that the presence of a heterozygous BRCA1 mutation is not associated with increased levels of indicators of oxidative stress in serum or lymphocytes. Future studies are warranted to evaluate whether strategies aimed at minimizing oxidative stress might aid in the prevention of hereditary breast cancer.

Visual pathway deficit in female fragile X premutation carriers: A potential endophenotype

Previous studies indicated impaired magnocellular (M) and relatively spared parvocellular (P) visual pathway functioning in patients with fragile X syndrome. In this study, we assessed M and P pathways in 22 female fragile X premutation carriers with normal intelligence and in 20 healthy non-carrier controls. Testing procedure included visual contrast sensitivity and vernier threshold measurements. Results revealed that carriers were selectively impaired on tests of M pathways (low spatial/high temporal frequency contrast sensitivity and frequency-doubling vernier), whereas they showed intact performance on P pathway tests. These results suggest that the deficit of the M pathway is an endophenotype of fragile X syndrome.

Impact of the Fragile X mental retardation 1 (FMR1) gene premutation on neuropsychiatric functioning in adult males without fragile X‐associated Tremor/Ataxia syndrome: A controlled study

Fragile X Syndrome is the most common heritable form of mental retardation caused by silencing of the FMR1 gene, which arises from intergenerational trinucleotide repeat expansion leading to full mutation. An intermediary carrier condition, known as the premutation, is characterized by expansion up to 200 repeats without concomitant gene silencing. This prevalent allelic variant was initially thought to be free of phenotypic effects. However, recent reports have identified a degenerative disease, Fragile X-associated Tremor/Ataxia Syndrome (FXTAS) in older men as well as premature ovarian failure in women. Previously reports are inconsistent regarding the neuropsychiatric phenotype associated with premutation due to small sample sizes, ascertainment bias, lack of adequate control groups, administration of measures with poor psychometric properties, and the confounding effects of FXTAS. We addressed these problems by conducting a controlled study of male carriers (n = 40) of the premutation without manifest symptoms of FXTAS, comparing their responses on specific, reliable, and valid measures of neuropsychiatric functioning to those of individuals with shared family environment (n = 22) and non-carrier comparison males (n = 43). Multivariate analyses revealed that the premutation confers significant risk for working memory difficulties, an associated feature of Attention-Deficit Disorder. Furthermore, both the family controls and men with premutation exhibited higher rates of Alcohol Abuse as compared to non-carrier control men. These findings highlight the importance of recognizing the distinct phenotypic outcomes that characterize the Fragile X premutation and the subtle risk factors that can act as precursors to more significant psychiatric impairment.

Amyloid Deposition Begins in the Striatum of Presenilin-1 Mutation Carriers from Two Unrelated Pedigrees

The amyloid cascade hypothesis suggests that the aggregation and deposition of amyloid-beta protein is an initiating event in Alzheimer's disease (AD). Using amyloid imaging technology, such as the positron emission tomography (PET) agent Pittsburgh compound-B (PiB), it is possible to explore the natural history of preclinical amyloid deposition in people at high risk for AD. With this goal in mind, asymptomatic (n = 5) and symptomatic (n = 5) carriers of presenilin-1 (PS1) mutations (C410Y or A426P) that lead to early-onset AD and noncarrier controls from both kindreds (n = 2) were studied with PiB-PET imaging and compared with sporadic AD subjects (n = 12) and controls from the general population (n = 18). We found intense and focal PiB retention in the striatum of all 10 PS1 mutation carriers studied (ages 35-49 years). In most PS1 mutation carriers, there also were increases in PiB retention compared with controls in cortical brain areas, but these increases were not as great as those observed in sporadic AD subjects. The two PS1 mutation carriers with a clinical diagnosis of early-onset AD did not show the typical regional pattern of PiB retention observed in sporadic AD. Postmortem evaluation of tissue from two parents of PS1C410Y subjects in this study confirmed extensive striatal amyloid deposition, along with typical cortical deposition. The early, focal striatal amyloid deposition observed in these PS1 mutation carriers is often is not associated with clinical symptoms.

Response to neo-adjuvant chemotherapy in women with BRCA1-positive breast cancers

There have been no studies to date which look at the relative effectiveness of different regimens of chemotherapy in women who have breast cancer and who carry a BRCA1 germ-line mutation. We wished to compare rates of response to neo-adjuvant chemotherapy in BRCA1 mutation carriers and non-carrier controls. From a registry of 3,479 patients, we identified 44 Polish women who carried a BRCA1 founder mutation and who had been treated with neo-adjuvant chemotherapy for breast cancer, and 41 age- and hospital-matched controls. 35 of the 44 BRCA1 mutation carriers (80%) experienced a partial or complete response to neo-adjuvant chemotherapy, compared to 39 of the 41 (95%) non-carriers (P=0.05). In the hereditary subgroup, response rates differed depending on whether or not a taxane (docetaxel) was given. Six of the 15 BRCA1 carrier women given docetaxel with doxorubicin responded (complete or partial), compared to 29 of 29 given other (DNA-damaging) therapies (P=0.001). Among the non-carriers, the rates of response to the two categories of chemotherapy were similar. Breast cancers among BRCA1 carriers frequently do not exhibit sensitivity to docetaxel in the neo-adjuvant setting. It is likely that normal BRCA1 is required for clinical response to mitotic spindle poisons.

Association of IL10 promoter polymorphism in Italian Alzheimer's disease

Recent studies have reported a genetic association between single nucleotide polymorphisms (SNPs) in the promoter region of Interleukin (IL) 10 and Alzheimer's disease (AD) with conflicting results. To further investigate the proposed association and to clarify the role of cytokines as a potential cause for AD susceptibility, we analyzed genotypes, allele distributions and haplotypes of IL10 promoter polymorphisms −1082 (rs1800896) and −819 (rs1800871) in an Italian sample of 222 sporadic AD patients and 179 normal controls. All 401 subjects were also genotyped for the Apolipoprotein E (ApoE) polymorphism. We reported a positive association between the −819T/C polymorphism and AD. Moreover, we found a significant difference for this SNP in the ApoE ɛ4 non-carrier AD patients compared to the ApoE ɛ4 non-carrier control group. For the −1082A genotype and allele distribution, no significant association was found in AD patients, although it was detected within the AT haplotype. Our results indicate that IL10 polymorphisms may be involved in the risk of developing AD.

Total antioxidant capacity of plasma in asymptomatic carrier state of Neisseria meningitidis.

Reduction of the antioxidant capacity of plasma has been linked with the impairment of an effective immune response and so we hypothesized that the carriage rate of Neisseria meningitidis in asymptomatic subjects might correlate with the levels of antioxidants in plasma. To this end we took pharyngeal swabs from 339 children in Marquesado Basic Health Zone, Granada, Spain and in addition determined the total antioxidant capacity (TAC) in plasma samples from these subjects. The overall prevalence of N. meningitidis carriage was 5.9% (mean age 7.1 years) with rates of 10.3% in children aged 3 < or =years, 3.9% between 4 and 7 years and 2.4% in older subjects. Plasma TAC for the < or =3-year-olds was 0.13 for carriers and 1.10 for non-carrier controls (P=0.04), 0.13 for carriers aged 4-7 years (controls 0.63) and 0.28 for carriers aged >7 years (controls 0.52). We analysed the association between TAC in plasma (<0.37 - 2 S.D.) and the carrier state of N. meningitidis. In the carrier state, the odds ratio for this association (TAC in plasma <0.25) was 8.44 (95% CI 1.5-48.9). These findings may suggest a reduced immune response in the host favourable to nasopharyngeal persistence of meningococci.

Potential advantage of N363S glucocorticoid receptor polymorphism in 21-hydroxylase deficiency

Congenital adrenal hyperplasia (CAH) shows a range of severity which is explained in part by the different mutations of the CYP21 gene. To better understand the incomplete concordance between genotype and phenotype in CAH the role of the sensitizing N363S polymorphism of the glucocorticoid receptor (GR) was examined in CAH patients. CAH patients were screened for N363S. Laboratory findings and clinical characteristics of carriers and non-carriers were analyzed retrospectively. The CYP21 gene of 200 CAH patients was analyzed by allele-specific PCR. The GR gene was tested for N363S by PCR followed by restriction fragment length polymorphism. Antropometric data (height, weight), degree of intrauterine virilization, hormone concentrations (17-OH-progesterone, dehydroepiandrosterone (DHEA), aldosterone, testosterone, plasma renin activity), substitution doses and clinical course were analyzed. The carrier frequency of N363S in CAH patients was equivalent to that of the general Hungarian population (6% vs 7.8%). Interestingly, none of the non-classical CAH (NC-CAH) patients were carriers of the polymorphism. Carrier girls had milder genital virilization than mutation-matched non-carrier controls. There was no significant difference between the carriers and non-carriers in either the substitution doses, the hormonal, or the auxiological parameters. The association of sensitizing the GR variant with impaired cortisol production in CAH might be compensatory in mild NC-CAH and may prevent severe intrauterine virilization in classical form. Although the exact role of N363S in extrauterine life should be further investigated, the consideration of certain genetic polymorphisms of CAH patients may lead to better, individualized therapeutic regimes.

Spontaneous and therapeutic abortions and the risk of breast cancer among BRCAmutation carriers

IntroductionBRCA1 and BRCA2 mutation carriers are at increased risk for developing both breast and ovarian cancer. It has been suggested that carriers of BRCA1/2 mutations may also be at increased risk of having recurrent (three or more) miscarriages. Several reproductive factors have been shown to influence the risk of breast cancer in mutation carriers, but the effects of spontaneous and therapeutic abortions on the risk of hereditary breast cancer risk have not been well studied to date.MethodsIn a matched case-control study, the frequencies of spontaneous abortions were compared among 1,878 BRCA1 mutation carriers, 950 BRCA2 mutation carriers and 657 related non-carrier controls. The rates of spontaneous and therapeutic abortions were compared for carriers with and without breast cancer.ResultsThere was no difference in the rate of spontaneous abortions between carriers of BRCA1 or BRCA2 mutations and non-carriers. The number of spontaneous abortions was not associated with breast cancer risk among BRCA1 or BRCA2 mutation carriers. However, BRCA2 carriers who had two or more therapeutic abortions faced a 64% decrease in the risk of breast cancer (odds ratio = 0.36; 95% confidence interval 0.16–0.83; p = 0.02).ConclusionCarrying a BRCA1 or BRCA2 mutation is not a risk factor for spontaneous abortions and spontaneous abortions do not appear to influence the risk of breast cancer in carriers of BRCA1 or BRCA2 mutations. However, having two or more therapeutic abortions may be associated with a lowered risk of breast cancer among BRCA2 carriers.

Increased level of chromosomal damage after irradiation of lymphocytes from BRCA1 mutation carriers

Deleterious mutations in the BRCA1 gene predispose women to an increased risk of breast and ovarian cancer. Many functional studies have suggested that BRCA1 has a role in DNA damage repair and failure in the DNA damage response pathway often leads to the accumulation of chromosomal aberrations. Here, we have compared normal lymphocytes with those heterozygous for a BRCA1 mutation. Short-term cultures were irradiated (8Gy) using a high dose rate and subsequently metaphases were analysed by 24-colour chromosome painting (M-FISH). We scored the chromosomal rearrangements in the metaphases from five BRCA1 mutation carriers and from five noncarrier control samples 6 days after irradiation. A significantly higher level of chromosomal damage was detected in the lymphocytes heterozygous for BRCA1 mutations compared with normal controls; the average number of aberrations per mitosis was 3.48 compared with 1.62 in controls (P=0.0001). This provides new evidence that heterozygous mutation carriers have a different response to DNA damage compared with noncarriers and that BRCA1 has a role in DNA damage surveillance. Our finding has implications for treatment and screening of BRCA1 mutation carriers using modalities that involve irradiation.

Distinct Hemostatic Profile of Leukocytes in Essential Thrombocythemia (ET) Carrying the JAK2 V617F Mutation.

The pathogenesis of the thrombotic diathesis of patients with ET is not completely clarified. Activation of polymorphonuclear leukocyte (PMN) occurs in these patients and is associated with a hypercoagulable state and increased number of circulating platelet/PMN aggregates. Further, increased procoagulant Tissue Factor (TF) expression in ET PMN is also reported. Recently, a gain-of-function JAK2 mutation (V617F) has been described in a high proportion of bcr/abl-negative myeloproliferative disorders. Specifically, in subjects with ET the mutation is present in about 50% of cases and retrospective data suggest an association with a higher rate of complications, including thrombosis. Aim of this study was to evaluate whether ET patients carrying the JAK2 mutation possess PMN with different hemostatic characteristics compared to ET subjects without JAK2 mutation and healthy controls. Twenty ET patients, 10 with and 10 without JAK2 mutation (median age: 50 years, range 32–61; platelet count: median 782 x 109/L, range 474–1,565 x 109/L), not receiving cytoreductive therapy (classified as low risk group), were included in the study; 16 age matched healthy subjects acted as controls. Expression of CD11b, TF and fibrinogen on PMN surface as well as PMN-platelet mixed aggregates (defined as the percentage of CD11b-positive PMN co-expressing a platelet-specific marker, i.e. CD42b or CD62P) were evaluated by whole blood flow-cytometry in both basal condition and after in vitro PMN stimulation by f-MLP. In washed isolated PMN samples the level of TF-mRNA was determined by RT-PCR. In basal conditions, significantly (p<0.01) increased levels of PMN/platelet aggregates (both CD42 and CD62P pos. PMN) compared to controls were found, independently from JAK2 mutation. Differently, PMN from JAK2 mutation carriers expressed significantly higher surface TF (18.2±9 %pos. cells) and fibrinogen (12.3±7 %pos. cells) antigens compared to non-carrier (TF: 11.6±5 %; fibrinogen: 7.2±2 %pos. cells) and control subjects (TF: 11.1±3 %; fibrinogen: 7.1±3 %pos. cells). In vitro stimulation with f-MLP increased the proportion of platelet/PMN aggregates (CD11b/CD42 and CD11b/CD62P) in all ET patients and controls. However, in JAK2 mutation carriers the levels of both CD62P and CD42b positive PMN were significantly greater than those of non-carrier ET patients and controls (p<0.05). Similarly, TF and fibrinogen levels on stimulated PMN surface were more elevated in the JAK2 mutation positive group compared to both the mutation negative and control groups. The analysis of PMN TF-mRNA showed a significantly higher expression in the whole ET patient group compared to controls, independently from the presence of JAK2 mutation. In conclusions, these data indicate that the expression of JAK2 mutation in ET patients may confer to PMN a different hemostatic phenotype in terms of increased interaction with platelets and increased expression of surface TF and fibrinogen, suggesting a new link of this mutation with a prothrombotic status.

Lymphocytes of BRCA1 and BRCA2 germ-line mutation carriers, with or without breast cancer, are not abnormally sensitive to the chromosome damaging effect of moderate folate deficiency

Mutations in BRCA1 and BRCA2 genes may cause defective DNA repair and increase the risk for breast cancer. Folate deficiency is associated with increased breast cancer risk and induces chromosome abnormalities. We hypothesized that BRCA1 and BRCA2 germline mutation carriers are more sensitive to the genome damaging effect of folate deficiency compared with healthy non-carrier controls and that this sensitivity is further increased in those carriers who develop breast cancer. We tested these hypotheses in lymphocytes cultured in a medium containing 12 or 120 nM folic acid (FA) for 9 days and measured proliferative capacity and chromosomal instability using the cytokinesis-block micronucleus assay. BRCA1 and BRCA2 mutation carriers with or without breast cancer were not abnormally sensitive to FA deficiency-induced chromosome instability; however, BRCA2 mutation carriers had significantly reduced cell proliferation. FA deficiency reduced cell proliferation and increased micronucleus formation significantly, accounting for 45-59% and 70-75% of the variance in these parameters compared with 0.3-8.5% and 0.2-0.3% contributed by BRCA1 or BRCA2 mutation carrier status, respectively. The results of this study suggest that moderate folate deficiency has a stronger effect on chromosomal instability than BRCA1 or BRCA2 mutations found in breast cancer families.

Audiometric evaluation of carriers of the connexin 26 mutation 35delG

Mutation in a gap junction protein gene (GJB2 also named connexin 26) is a major cause of autosomal recessive congenital deafness, which is responsible for about 80% of the cases in Mediterranean families, but actually little is known about the influence of GJB2 mutations on the hearing of obligate carriers. We examined GJB2 35delG mutation carrier individuals to test the possible presence and incidence of audiometric abnormalities among carriers of 35delG mutations. Tonal audiometric analysis was performed on a 35delG mutation carrier group (H) and on a non-carrier control group (N). Audiometric evaluations in the control group showed the presence of thresholds within normal limits at all frequencies, while carriers of 35delG mutations presented a decrease of hearing principally at 6,000 and 8,000 Hz. The difference at 6,000 and 8,000 Hz between groups H and N is statistically significant.

Increased Rates of Chromosome Breakage in BRCA1 Carriers Are Normalized by Oral Selenium Supplementation

Women who are born with constitutional heterozygous mutations of the BRCA1 gene face greatly increased risks of breast and ovarian cancer. The product of the BRCA1 gene is involved in the repair of double-stranded DNA breaks and it is believed that increased susceptibility to DNA breakage contributes to the cancer phenotype. It is hoped therefore that preventive strategies designed to reduce chromosome damage will also reduce the rate of cancer in these women. To test for increased mutagenicity of cells from BRCA1 carriers, the frequency of chromosome breaks was measured in cultured blood lymphocytes following in vitro exposure to bleomycin in female BRCA1 carriers and was compared with noncarrier relatives. The frequency of chromosome breaks was also measured in BRCA1 carriers following oral selenium supplementation. Carriers of BRCA1 mutations showed significantly greater mean frequencies of induced chromosome breaks per cell than did healthy noncarrier relatives (0.58 versus 0.39; P < 10(-4)). The frequency of chromosome breaks was greatly reduced following 1 to 3 months of oral selenium supplementation (mean, 0.63 breaks per cell versus 0.40; P < 10(-10)). The mean level of chromosome breaks in carriers following supplementation was similar to that of the noncarrier controls (0.40 versus 0.39). Oral selenium is a good candidate for chemoprevention in women who carry a mutation in the BRCA1 gene.

241 EFFECT OF INTRODUCTION OF THE INVERDALE FECUNDITY (FecXI) GENE INTO A TEXEL × SCOTTISH HILL EWE (CHEVIOT) FLOCK ON LITTER SIZE, BIRTHWEIGHT, AND LAMB SURVIVAL

The naturally occurring Inverdale fecundity gene (FecXI), first identified in a Romney flock in New Zealand is located on the X-chromosome and is a point mutation of the bone morphogenetic protein-15 (BMP-15) gene. Although homozygous carriers are infertile due to abnormal development (hypoplasia) of the ovaries, heterozygotes exhibit an increase in ovulation rate and numbers of lambs born, thus making the gene a candidate for improving prolificacy of crossbred hill ewes in a stratified hill and lowground sheep industry. Heterozygous Inverdale gene-carrying crossbred (Texel � Cheviot) ewes (n = 76) and noncarrier controls (n = 18) were mated by non-carrier Texel rams at approximately 18 months of age. Ultrasound pregnancy scanning took place at approximately 70 days of gestation. Lambing records comprised litter size and birthweight data and all losses, including mummified fetuses. Regression analysis tested effects of ewe genotype, pre-mating liveweight, and body condition score on litter size. ANOVA and Kruskal-Wallis tests were used to compare genotype and litter size category effects on dam and offspring data. Mean (� SEM) litter size was 2.6 � 0.10 and 1.9 � 0.11 for FecXI carrier and noncarrier ewes (P &lt; 0.001). Although carrier ewes had lower pre-mating liveweights (60 � 5.2 vs. 63 � 3.8 kg; P &lt; 0.05) and body condition scores (3.1 � 0.29 vs. 3.3 � 0.24; P &lt; 0.01) than noncarrier ewes, litter size was not affected by either factor. Ultrasound scanning was a good predictor (r2 = 0.86; P &lt; 0.001) of the eventual lamb crop. Incidences of singletons, twins, triplets and higher multiples were 8, 38, 42 and 12%, respectively, among FecXI carrier dams. Corresponding incidences among noncarriers were 17, 78, 5, and 0%. Peri- and neonatal losses increased with litter size. Of lambs from single, twin or triplet births, losses were 20% and 6% for FecXI carrier and noncarrier ewe groups, respectively (P = 0.049). Of 32 quadruplets (mean live weight = 2.65 kg), 9 did not survive; the sole set of quintuplets (mean = 1.52 kg) also succumbed. Birth weights of lambs influenced survival (P &lt; 0.001); among quadruplets, for example, survivors were 0.5 kg heavier than counterparts that died. Surviving triplets from FecXI carrier dams were 0.8 kg heavier than non-survivors (3.66 kg vs. 2.86 kg). Overall, in this study mortality was four times greater among lambs below 3 kg live weight than among their heavier counterparts. Consequently, further studies are needed to investigate how Inverdale gene-carrying ewes can be managed during the peri-conception period to optimize litter size, placental function, and prenatal growth for maximum lamb survival. This work was funded by HIE, ANM Group, Britbreed, Ltd., and Harbro Ltd.; F. M. A. is a Genesis Faraday Associate and is sponsored by the SAC Trust, Harbro, Ltd., and Innovis.

The Response to Activated Protein C After Cardiopulmonary Bypass: Impact of Factor V Leiden

Activated protein C (aPC) resistance is a recognized hypercoagulable phenotype that is associated with increased risk for thrombosis in multiple clinical settings. Factor V Leiden (FVL) represents a specific inherited cause of aPC resistance, but the perioperative thrombotic risk of FVL is unclear. In this investigation, we sought to quantify whether cardiopulmonary bypass produces alterations in aPC resistance in FVL carriers and noncarrier controls, testing the hypothesis that FVL is associated with a relatively hypercoagulable postoperative state. Two-hundred-five adult cardiac surgery patients were prospectively enrolled into a genetic registry whose purpose was to study the impact of genetic variables on clinical outcomes. For this study, 8 subjects heterozygous for FVL were identified (group L), as well as 2 control groups: group MC, matched controls, 18 matched subjects without FVL; and group UC, unmatched controls, 11 consecutive subjects without FVL. Plasma was sampled at the beginning of surgery, 10 min after protamine administration, and on postoperative day 1, and assayed for resistance to aPC (normal aPC ratio is >2.0). Both MC and UC groups exhibited normal aPC ratio at baseline (2.40 and 2.36, respectively), which increased significantly (to 2.76 and 2.75, P = 0.007 and 0.021, respectively) on postoperative day 1, indicating increased postoperative sensitivity to aPC. Conversely, group L subjects exhibited aPC resistance at baseline (aPC ratio 1.80), and did not change significantly postoperatively (P = 0.867). Patients without FVL therefore show laboratory evidence consistent with relative protection from postoperative thrombosis, whereas FVL carriers do not. These findings provide mechanistic support for previous speculations of increased postoperative thrombotic risk associated with FVL.