Hypolactasia and metabolic changes in post-menopausal women

Lactose intolerance in children and adults

Lactose is a disaccharide found in milk and dairy products. Children and adults with lactose intolerance are unable to tolerate significant amounts of lactose because of an inadequate amount of the enzyme lactase. The condition occurs in three main types: primary, secondary, and primary adult-type hypolactasia. The use of milk in the diet of these individuals may lead to appearance of the irritable bowel syndrome. In persons with lactose intolerance symptoms include diarrhoea, dominated by abdominal colic, loud peristaltic sounds, increased flatulence and meteorism. A diagnosis of lactose intolerance can usually be made with a careful history, elimination of lactose from the diet, lactose tolerance test, hydrogen breath test and genetic testing. In the absence of appropriate tests in patients with suspected primary adult-type hypolactasia, diagnosis can be made as in patients with food allergy. Treatment is based on the restriction of lactose intake with the use of fermented milk products. However, especially for children, if milk and dairy products are eliminated from the diet, it is important to ensure D vitamin and calcium supplementation.

Haemostaseome-associated SNPs: has the thrombotic phenotype a greater influence than ethnicity? GMT study from Aquitaine including Basque individuals

The Genetic Markers for Thrombosis (GMT) study compared the relative influence of ethnicity and thrombotic phenotype regarding the distribution of SNPs implicated in haemostasis pathophysiology ("haemostaseome"). We assessed 384 SNPs in three groups, each of 480 subjects: 1) general population of Aquitaine region (Southwestern France) used as control; 2) patients with venous thromboembolism from the same area; and 3) autochthonous Basques, a genetic isolate, who demonstrate unusual characteristics regarding the coagulation system. This study sought to evaluate i) the value of looking for a large number of genes in order to identify new genetic markers of thrombosis, ii) the value of investigating low risk factors and potential preferential associations, iii) the impact of ethnicity on the characterisation of markers for thrombosis. We did not detect any previously unrecognised SNP significantly associated with thrombosis risk or any preferential associations of low-risk factors in patients with thrombosis. The sum of ϰ² values for our 110 significant SNPs demonstrated a smaller genetic distance between patients and controls (321 cumulated ϰ² value) than between Basques and controls (1,570 cumulated ϰ² value). Hence, our study confirms the genetic particularity of Basques especially regarding a significantly lower expression of the non-O blood group (p< 0.0004). This is mitigated by a higher prevalence of factor II Leiden (p< 0.02) while factor V Leiden prevalence does not differ. Numerous other differences covering a wide range of proteins of the haemostaseome may result in an overall different genetic risk for venous thromboembolism.

Genetic dissection of the pre-eclampsia susceptibility locus on chromosome 2q22 reveals shared novel risk factors for cardiovascular disease

Pre-eclampsia is an idiopathic pregnancy disorder promoting morbidity and mortality to both mother and child. Delivery of the fetus is the only means to resolve severe symptoms. Women with pre-eclamptic pregnancies demonstrate increased risk for later life cardiovascular disease (CVD) and good evidence suggests these two syndromes share several risk factors and pathophysiological mechanisms. To elucidate the genetic architecture of pre-eclampsia we have dissected our chromosome 2q22 susceptibility locus in an extended Australian and New Zealand familial cohort. Positional candidate genes were prioritized for exon-centric sequencing using bioinformatics, SNPing, transcriptional profiling and QTL-walking. In total, we interrogated 1598 variants from 52 genes. Four independent SNP associations satisfied our gene-centric multiple testing correction criteria: a missense LCT SNP (rs2322659, P = 0.0027), a synonymous LRP1B SNP (rs35821928, P = 0.0001), an UTR-3 RND3 SNP (rs115015150, P = 0.0024) and a missense GCA SNP (rs17783344, P = 0.0020). We replicated the LCT SNP association (P = 0.02) and observed a borderline association for the GCA SNP (P = 0.07) in an independent Australian case-control population. The LRP1B and RND3 SNP associations were not replicated in this same Australian singleton cohort. Moreover, these four SNP associations could not be replicated in two additional case-control populations from Norway and Finland. These four SNPs, however, exhibit pleiotropic effects with several quantitative CVD-related traits. Our results underscore the genetic complexity of pre-eclampsia and present novel empirical evidence of possible shared genetic mechanisms underlying both pre-eclampsia and other CVD-related risk factors.

Adult-type hypolactasia and calcium intake in polycystic ovary syndrome

OBJECTIVE

Adult-type hypolactasia (ATH) is related to lower calcium and milk intake, which might be associated with obesity and metabolic disturbances. Women with polycystic ovary syndrome (PCOS) frequently suffer from metabolic disturbances including central obesity. We aimed to examine the association of ATH and calcium intake with anthropometric, metabolic and endocrine parameters in a cohort of PCOS and control women.

DESIGN

Metabolic, endocrine and anthropometric measurements and oral glucose tolerance tests were performed in 504 PCOS and 366 control women. Genotyping of ATH, defined by the -13910 variant of the MCM6 gene, was performed. Calcium intake was assessed by questionnaires.

RESULTS

Adult-type hypolactasia was more prevalent in PCOS women (29·8%) than in controls (23·5%) (P = 0·040). PCOS women with ATH had higher waist-to-hip ratio (WHR) (0·80 [0·75-0·88] vs 0·78 [0·73-0·85], P = 0·046), glucose 2 h (5·28 [4·57-6·33] mmol/l vs 5·67 [4·68-6·78] mmol/l, P = 0·037), HbA1c (5·2 [5·0-5·4]%vs 5·1 [5·0-5·3]%, P = 0·009), parathyroid hormone (3·72(2·91-4·86] pmol/l vs 3·61 [2·94-4·63] pmol/l, P = 0·030) and Ferriman-Gallwey-Scores (FG Scores) (7 [3-12] vs 4 [1-9], P = 0·002) and lower 25(OH)D levels (54·4 [35·2-80·6] nmol/l vs 68·4 [49·7-89·4] nmol/l, P < 0·001) than PCOS women without ATH. The association of 25(OH)D and FG-Scores with ATH remained significant in age-, BMI- and WHR-adjusted analyses. PCOS women within the highest quartile of calcium intake had significantly lower testosterone (P = 0·023) and androstenedione (P = 0·032) and significantly higher high-density lipoprotein (HDL) levels (P = 0·035) than PCOS women with lower calcium intake.

CONCLUSION

Our results indicate an association of ATH with PCOS susceptibility. Moreover, ATH might influence WHR, HbA1c and FG-Scores as well as 25(OH)D levels. Higher calcium intake was associated with lower androgens and higher HDL levels.

Adult-type hypolactasia is not a predisposing factor for the early functional and structural changes of atherosclerosis: the Cardiovascular Risk in Young Finns Study

Individuals suffering from ATH (adult-type hypolactasia), defined by the LCT (gene encoding lactase-phlorizin hydrolase) C/C(-13910) genotype (rs4988235), use less milk and dairy products and may have higher plasma HDL (high-density lipoprotein) and lower triacylglycerol (triglyceride) concentrations than their counterparts without ATH. To investigate the effects of ATH status on the early markers of atherosclerosis, we examined its association with CIMT (carotid intima-media thickness), CAC (carotid artery compliance) and brachial artery FMD (flow-mediated dilation) in a young population-based cohort of otherwise healthy individuals. As part of the Cardiovascular Risk in Young Finns Study, we performed CIMT, CAC and FMD analyses, LCT C/T(-13910) genotyping and risk factor determination in 2109 young subjects 24-39 years of age (45% males) at the time of the examination. The consumption of both milk and dairy products was lowest and the consumption of alcohol highest in subjects with the C/C(-13910) genotype (P<0.001 for all) in comparison with subjects without ATH (TT+CT). In multivariate analysis, no significant association between ATH status and CIMT, CAC or brachial artery FMD was found after adjustment for the use of alcohol, dairy products and all other major risk factors of coronary artery disease. In otherwise similar statistical analysis, the results remained non-significant when females and males were analysed in their own groups. In conclusion, the finding does not support the involvement of ATH in the pathogenesis of early atherosclerosis.

Gender differences in genetic risk profiles for cardiovascular disease

BACKGROUND

Cardiovascular disease (CVD) incidence, complications and burden differ markedly between women and men. Although there is variation in the distribution of lifestyle factors between the genders, they do not fully explain the differences in CVD incidence and suggest the existence of gender-specific genetic risk factors. We aimed to estimate whether the genetic risk profiles of coronary heart disease (CHD), ischemic stroke and the composite end-point of CVD differ between the genders.

METHODOLOGY/PRINCIPAL FINDINGS

We studied in two Finnish population cohorts, using the case-cohort design the association between common variation in 46 candidate genes and CHD, ischemic stroke, CVD, and CVD-related quantitative risk factors. We analyzed men and women jointly and also conducted genotype-gender interaction analysis. Several allelic variants conferred disease risk for men and women jointly, including rs1801020 in coagulation factor XII (HR = 1.31 (1.08-1.60) for CVD, uncorrected p = 0.006 multiplicative model). Variant rs11673407 in the fucosyltransferase 3 gene was strongly associated with waist/hip ratio (uncorrected p = 0.00005) in joint analysis. In interaction analysis we found statistical evidence of variant-gender interaction conferring risk of CHD and CVD: rs3742264 in the carboxypeptidase B2 gene, p(interaction) = 0.009 for CHD, and rs2774279 in the upstream stimulatory factor 1 gene, p(interaction) = 0.007 for CHD and CVD, showed strong association in women but not in men, while rs2069840 in interleukin 6 gene, p(interaction) = 0.004 for CVD, showed strong association in men but not in women (uncorrected p-values). Also, two variants in the selenoprotein S gene conferred risk for ischemic stroke in women, p(interaction) = 0.003 and 0.007. Importantly, we identified a larger number of gender-specific effects for women than for men.

CONCLUSIONS/SIGNIFICANCE

A false discovery rate analysis suggests that we may expect half of the reported findings for combined gender analysis to be true positives, while at least third of the reported genotype-gender interaction results are true positives. The asymmetry in positive findings between the genders could imply that genetic risk loci for CVD are more readily detectable in women, while for men they are more confounded by environmental/lifestyle risk factors. The possible differences in genetic risk profiles between the genders should be addressed in more detail in genetic studies of CVD, and more focus on female CVD risk is also warranted in genome-wide association studies.