The objective of this study was to describe the prevalence of Klinefelter syndrome (KS) prenatally and postnatally in Denmark and determine the influence of maternal age. All chromosomal examinations in Denmark are registered in the Danish Cytogenetic Central Registry. Individuals with KS diagnosed prenatally or postnatally were extracted from the registry with information about age at the time of diagnosis and mother's age. In the period 1970-2000, 76,526 prenatal examinations on male fetuses resulted in the diagnosis of 163 fetuses with KS karyotype, corresponding to a prevalence of 213 per 100,000 male fetuses. Standardization according to maternal age resulted in a prevalence of 153 per 100,000 males. Postnatally, 696 males of 2,480,858 live born were diagnosed with KS, corresponding to a prevalence among adult men of approximately 40 per 100,000. Less than 10% of the expected number was diagnosed before puberty. Advanced maternal age had a significant impact on the prevalence. KS is severely underdiagnosed in Denmark. Only approximately one fourth of adult males with KS are diagnosed. There is a marked delay in diagnosis of the syndrome. A delay in treatment with testosterone may lead to decreased muscle and bone mass with subsequent risk of osteoporosis.

To identify common alleles associated with different histotypes of epithelial ovarian cancer (EOC), we pooled data from multiple genome-wide genotyping projects totaling 25,509 EOC cases and 40,941 controls. We identified nine new susceptibility loci for different EOC histotypes: six for serous EOC histotypes (3q28, 4q32.3, 8q21.11, 10q24.33, 18q11.2 and 22q12.1), two for mucinous EOC (3q22.3, 9q31.1) and one for endometrioid EOC (5q12.3). We then meta-analysed the results for high-grade serous ovarian cancer with the results from analysis of 31,448 BRCA1 and BRCA2 mutation carriers, including 3,887 mutation carriers with EOC. This identified an additional three loci at 2q13, 8q24.1 and 12q24.31. Integrated analyses of genes and regulatory biofeatures at each locus predicted candidate susceptibility genes, including OBFC1, a novel susceptibility gene for low grade/borderline serous EOC.

IMPORTANCE Limited information about the relationship between specific mutations in BRCA1 or BRCA2 (BRCA1/2) and cancer risk exists. OBJECTIVE To identify mutation-specific cancer risks for carriers of BRCA1/2. DESIGN, SETTING, AND PARTICIPANTS Observational study of women who were ascertained between 1937 and 2011 (median, 1999) and found to carry disease-associated BRCA1 or BRCA2 mutations. The international sample comprised 19 581 carriers of BRCA1 mutations and 11 900 carriers of BRCA2 mutations from 55 centers in 33 countries on 6 continents. We estimated hazard ratios for breast and ovarian cancer based on mutation type, function, and nucleotide position. We also estimated RHR, the ratio of breast vs ovarian cancer hazard ratios. A value of RHR greater than 1 indicated elevated breast cancer risk; a value of RHR less than 1 indicated elevated ovarian cancer risk. EXPOSURES Mutations of BRCA1 or BRCA2. MAIN OUTCOMES AND MEASURES Breast and ovarian cancer risks. RESULTS Among BRCA1 mutation carriers, 9052 women (46%) were diagnosed with breast cancer, 2317 (12%) with ovarian cancer, 1041 (5%) with breast and ovarian cancer, and 7171 (37%) without cancer. Among BRCA2 mutation carriers, 6180 women (52%) were diagnosed with breast cancer, 682 (6%) with ovarian cancer, 272 (2%) with breast and ovarian cancer, and 4766 (40%) without cancer. In BRCA1, we identified 3 breast cancer cluster regions (BCCRs) located at c.179 to c.505 (BCCR1; RHR = 1.46; 95% CI, 1.22–1.74; P = 2 × 10−6), c.4328 to c.4945 (BCCR2; RHR = 1.34; 95% CI, 1.01–1.78; P = .04), and c. 5261 to c.5563 (BCCR23, RHR = 1.38; 95% CI, 1.22–1.55; P = 6 × 10−9). We also identified an ovarian cancer cluster region (OCCR) from c.1380 to c.4062 (approximately exon 11) with RHR = 0.62 (95% CI, 0.56–0.70; P = 9 × 10−17). In BRCA2, we observed multiple BCCRs spanning c.1 to c.596 (BCCR1; RHR = 1.71; 95% CI, 1.06–2.78; P = .03), c.772 to c.1806 (BCCR13; RHR = 1.63; 95% CI, 1.10–2.40; P = .01), and c.7394 to c.8904 (BCCR2; RHR = 2.31; 95% CI, 1.69–3.16; P = .00002). We also identified 3 OCCRs: the first (OCCR1) spanned c.3249 to c.5681 that was adjacent to c.5946delT (6174delT; RHR = 0.51; 95% CI, 0.44–0.60; P = 6 × 10−17). The second OCCR spanned c.6645 to c.7471 (OCCR2; RHR = 0.57; 95% CI, 0.41–0.80; P = .001). Mutations conferring nonsense-mediated decay were associated with differential breast or ovarian cancer risks and an earlier age of breast cancer diagnosis for both BRCA1 and BRCA2 mutation carriers. CONCLUSIONS AND RELEVANCE Breast and ovarian cancer risks varied by type and location of BRCA1/2 mutations. With appropriate validation, these data may have implications for risk assessment and cancer prevention decision making for carriers of BRCA1 and BRCA2 mutations.

More emphasis should be placed on increasing the rate of diagnosis and generating evidence for timing and dose of testosterone replacement. Treatment of KS should be a multidisciplinary task including pediatricians, speech therapists, general practitioners, psychologists, infertility specialists, urologists, and endocrinologists.

Most common breast cancer susceptibility variants have been identified through genome-wide association studies (GWAS) of predominantly estrogen receptor (ER)-positive disease1. We conducted a GWAS using 21,468 ER-negative cases and 100,594 controls combined with 18,908 BRCA1 mutation carriers (9,414 with breast cancer), all of European origin. We identified independent associations at P < 5 × 10−8 with ten variants at nine new loci. At P < 0.05, we replicated associations with 10 of 11 variants previously reported in ER-negative disease or BRCA1 mutation carrier GWAS and observed consistent associations with ER-negative disease for 105 susceptibility variants identified by other studies. These 125 variants explain approximately 14% of the familial risk of this breast cancer subtype. There was high genetic correlation (0.72) between risk of ER-negative breast cancer and breast cancer risk for BRCA1 mutation carriers. These findings may lead to improved risk prediction and inform further fine-mapping and functional work to better understand the biological basis of ER-negative breast cancer.

OBJECTIVE—Klinefelter’s syndrome is associated with an increased prevalence of diabetes, but the pathogenesis is unknown. Accordingly, the aim of this study was to investigate measures of insulin sensitivity, the metabolic syndrome, and sex hormones in patients with Klinefelter’s syndrome and an age-matched control group. RESEARCH DESIGN AN METHODS—In a cross-sectional study, we examined 71 patients with Klinefelter’s syndrome, of whom 35 received testosterone treatment, and 71 control subjects. Body composition was evaluated using dual-energy X-ray absorptiometry scans. Fasting blood samples were analyzed for sex hormones, plasma glucose, insulin, C-reactive protein (CRP), and adipocytokines. We analyzed differences between patients with untreated Klinefelter’s syndrome and control subjects and subsequently analyzed differences between testosterone-treated and untreated Klinefelter’s syndrome patients. RESULTS—Of the patients with Klinefelter’s syndrome, 44% had metabolic syndrome (according to National Cholesterol Education Program/Adult Treatment Panel III criteria) compared with 10% of control subjects. Insulin sensitivity (assessed by homeostasis model assessment 2 modeling), androgen, and HDL cholesterol levels were significantly decreased, whereas total fat mass and LDL cholesterol, triglyceride, CRP, leptin, and fructosamine levels were significantly increased in untreated Klinefelter’s syndrome patients. In treated Klinefelter’s syndrome patients, LDL cholesterol and adiponectin were significantly decreased, whereas no difference in body composition was found in comparison with untreated Klinefelter’s syndrome patients. Multivariate analyses showed that truncal fat was the major determinant of metabolic syndrome and insulin sensitivity. CONCLUSIONS—The prevalence of metabolic syndrome was greatly increased, whereas insulin sensitivity was decreased in Klinefelter’s syndrome. Both correlated with truncal obesity. Hypogonadism in Klinefelter’s syndrome may cause an unfavorable change in body composition, primarily through increased truncal fat and decreased muscle mass. Testosterone treatment in Klinefelter’s syndrome only partly corrected the unfavorable changes observed in untreated Klinefelter’s syndrome, perhaps due to insufficient testosterone doses.

Males suffering from KS experienced an increased hospitalization rate from a variety of disorders. Some are likely to be caused by hypogonadism, and some may be linked to the syndrome per se, whereas others are not readily explained. However, other factors, e.g. socioeconomic, may be involved.

Klinefelter syndrome is the most common sex-chromosome disorder; it affects approximately one in every 660 men. This syndrome is characterized by the presence of one or more extra X chromosomes, and the karyotype 47,XXY is the most prevalent type. The 'prototypic' man with Klinefelter syndrome has traditionally been described as tall, with narrow shoulders, broad hips, sparse body hair, gynecomastia, small testicles, androgen deficiency, azoospermia and decreased verbal intelligence. A less distinct phenotype has, however, been described. Klinefelter syndrome is an underdiagnosed condition; only 25% of the expected number of patients are diagnosed, and of these only a minority are diagnosed before puberty. Patients with Klinefelter syndrome should be treated with lifelong testosterone supplementation that begins at puberty, to secure proper masculine development of sexual characteristics, muscle bulk and bone structure, and to prevent the long-term deleterious consequences of hypogonadism; however, the optimal testosterone regimen for patients with Klinefelter syndrome remains to be established.