In this task, you are given a passage which has a question and the context. You have to generate an answer to the question based on the information present in the context.

[EX Q]: Context: Human breast tumors are heterogeneous and consist of phenotypically diverse cells. Breast cancer cells with a CD44+/CD24- phenotype have been suggested to have tumor-initiating properties with stem cell-like and invasive features, although it is unclear whether their presence within a tumor has clinical implications. There is also a large heterogeneity between tumors, illustrated by reproducible stratification into various subtypes based on gene expression profiles or histopathological features. We have explored the prevalence of cells with different CD44/CD24 phenotypes within breast cancer subtypes.', 'Double-staining immunohistochemistry was used to quantify CD44 and CD24 expression in 240 human breast tumors for which information on other tumor markers and clinical characteristics was available. Gene expression data were also accessible for a cohort of the material.', 'A considerable heterogeneity in CD44 and CD24 expression was seen both between and within tumors. A complete lack of both proteins was evident in 35% of the tumors, while 13% contained cells of more than one of the CD44+/CD24-, CD44-/CD24+ and CD44+/CD24+ phenotypes. CD44+/CD24- cells were detected in 31% of the tumors, ranging in proportion from only a few to close to 100% of tumor cells. The CD44+/CD24- phenotype was most common in the basal-like subgroup--characterized as negative for the estrogen and progesterone receptors as well as for HER2, and as positive for cytokeratin 5/14 and/or epidermal growth factor receptor, and particularly common in BRCA1 hereditary tumors, of which 94% contained CD44+/CD24- cells. The CD44+/CD24- phenotype was surprisingly scarce in HER2+ tumors, which had a predominantly CD24+ status. A CD44+/CD24- gene expression signature was generated, which included CD44 and alpha6-integrin (CD49f) among the top-ranked overexpressed genes.\Question: Does the CD44+/CD24- phenotype is enriched in basal-like breast tumors?
[EX A]: We demonstrate an association between basal-like and particularly BRCA1 hereditary breast cancer and the presence of CD44+/CD24- cells. Not all basal-like tumors and very few HER2+ tumors, however, contain CD44+/CD24- cells, emphasizing that a putative tumorigenic ability may not be confined to cells of this phenotype and that other breast cancer stem cell markers remain to be identified.

[EX Q]: Context: Intrahepatic cholestasis of pregnancy (ICP) is defined by pruritus, elevated total fasting serum bile salts (TBS) and transaminases, and an increased risk of adverse fetal outcome. An accurate diagnostic marker is needed. Increased serum autotaxin correlates with cholestasis-associated pruritus. We aimed at unraveling the diagnostic accuracy of autotaxin in ICP.', 'Serum samples and placental tissue were collected from 44 women with uncomplicated pregnancies and 105 with pruritus and/or elevated serum transaminases. Autotaxin serum levels were quantified enzymatically and by Western blotting, autotaxin gene expression by quantitative PCR.', 'Serum autotaxin was increased in ICP (mean ± SD: 43.5 ± 18.2 nmol ml(-1)min(-1), n=55, p<0.0001) compared to other pruritic disorders of pregnancy (16.8 ± 6.7 nmol ml(-1)min(-1), n=33), pre-eclampsia complicated by HELLP-syndrome (16.8 ± 8.9 nmol ml(-1)min(-1), n=17), and pregnant controls (19.6 ± 5.7 nmol ml(-1)min(-1), n=44). Longitudinal analysis during pregnancy revealed a marked rise in serum autotaxin with onset of ICP-related pruritus. Serum autotaxin was increased in women taking oral contraceptives. Increased serum autotaxin during ICP was not associated with increased autotaxin mRNA in placenta. With a cut-off value of 27.0 nmol ml(-1)min(-1), autotaxin had an excellent sensitivity and specificity in distinguishing ICP from other pruritic disorders or pre-eclampsia/HELLP-syndrome. Serum autotaxin displayed no circadian rhythm and was not influenced by food intake.\Question: Does autotaxin activity have a high accuracy to diagnose intrahepatic cholestasis of pregnancy?
[EX A]: Increased serum autotaxin activity represents a highly sensitive, specific and robust diagnostic marker of ICP, distinguishing ICP from other pruritic disorders of pregnancy and pregnancy-related liver diseases. Pregnancy and oral contraception increase serum autotaxin to a much lesser extent than ICP.

[EX Q]: Context: The "hygiene hypothesis" postulates that individuals raised in a sanitary environment are more likely to develop inflammatory bowel disease (IBD). Several studies previously demonstrated contradictory results in this regard. We performed for the first time a population-based study on the association of surrogate markers of childhood hygiene with the risk for IBD.', 'A cross-sectional population-based study was undertaken. Information on number of siblings, birth order, and living in an urban versus rural environment was obtained for 399,251 Jewish adolescents at the age of 17 yr from 1998 to 2004. The study population included only subjects born in Israel. In order to control for genetic confounding, subjects were also divided according to their ethnic group as being Ashkenazi, Sephardic, or Israeli in origin.', 'In total, 768 cases of inflammatory bowel disease (IBD) were diagnosed (0.19%), with 53.8% of the cases being of Ashkenazi origin. On multivariate analysis, variables significantly associated with IBD were male gender (odds ratio [OR] 1.44, 95% confidence interval [CI] 1.24-1.67), Ashkenazi origin (OR 1.91, 95% CI 1.63-2.22), living in an urban environment (OR 1.38, 95% CI 1.02-1.78), small number of siblings in the family (for 1 sibling vs 5 or more, OR 2.63, 95% CI 1.49-4.62), and higher birth order (for birth order of 5 or higher vs 1, OR 2.35, 95% CI 1.47-3.77), showing for both variables an almost strictly highly significant monotonic association (P value for trend <0.001).\Question: Is childhood hygiene associated with the risk for inflammatory bowel disease : a population-based study?
[EX A]:
Surrogate markers of childhood hygiene are associated with the risk for IBD, thus reinforcing the "hygiene hypothesis."