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The article presents a study which determined whether certain groups of discordant congenital heart defects (CHDs) are more common in families than others. It explains how a single gene can produce different CHDs within a family as evidenced by previous research. The study documented a general aggregation of dissimilar CHDs in families and found no excess clustering of specific CHD phenotypes among first-degree relatives. The study confirmed that aggregation of discordant CHDs is not likely to be exclusively environmental in origin.

It has been suggested that cryptorchidism and hypospadias may be the result of a common pathologic pathway that causes testicular dysgenesis during fetal life. To address the potential heritability of this pathway, we specifically examined to what extent a family history of cryptorchidism increases the risk of developing hypospadias and vice versa.By using Danish health registers, we identified 27,762 boys diagnosed with cryptorchidism and 4832 boys diagnosed with hypospadias in a cohort of 1,018,517 boys born during 1977-2005. Using binomial log-linear regression, we estimated risk ratios of cryptorchidism and hypospadias in male twin pairs and first-, second-, and third-degree relatives with a family history of hypospadias and cryptorchidism, respectively.After adjusting for birth period and personal hypospadias/cryptorchidism status, there was little evidence of increased risk of cryptorchidism given a family history of hypospadias, and vice versa. However, cryptorchidism and hypospadias was associated on an individual level.We found no persuasive evidence that a family history of hypospadias increases the risk of cryptorchidism and vice versa. Thus, we found no support for shared heritability of hypospadias and cryptorchidism. [ABSTRACT FROM AUTHOR]

Infant deaths cluster in families, but beyond infancy, little is known about familial aggregation of premature deaths. We hypothesized that an individual's risk of premature death would be influenced by prior premature deaths of any age in family members.For all Danish residents registered in the Civil Registration System, 1968-2005, information was linked to the Causes of Death Register and the Danish Family Relation Database, yielding a cohort of 4,870,821 persons linked to one or more relatives (93 million persons-years and 73,278 deaths). We used log-linear Poisson regression to estimate mortality rate ratios (relative risks) for premature death (before age 40 years) in persons with a family history of premature death, compared with persons without such a history.Persons with a family history of premature death were 46% more likely themselves to die prematurely than persons without such a family history (relative risk [RR] = 1.46 [95% confidence interval = 1.42-1.50]). Relative risks were higher for concordant age at death, a close kinship relation, and similar causes of death. As expected, certain natural causes clustered among first-degree relatives (RRs ranged from 1.81-618), but unnatural causes of death, such as nonsimultaneous motor vehicle injuries, other injuries, and suicides, also clustered (RRs = 1.80, 3.53, and 4.23, respectively). Previous family history of premature death in a first-degree relative also increased the risk of dying from another cause (overall RR = 2.08 in infancy and 1.33 between ages 1 and 39).Premature deaths cluster in families, for both similar and dissimilar causes. [ABSTRACT FROM AUTHOR]

Intussusception is the most common cause of intestinal obstruction in infancy and early childhood, but its etiology remains unknown. The present study analyzes whether some children with intussusception subsequently have a higher risk of tonsil disease, suggesting an enhanced tendency to lymphoid hyperplasia.This nationwide cohort study included all Danish children younger than age 15 years, who were born in 1977-2001 and diagnosed with intussusception at a hospital (n = 2018). The cohort was followed-up for tonsil disease in the Danish National Patient Registry and the Danish Health Security System.A total of 172 children were identified with tonsil disease following intussusception. The risk of tonsil disease was 48% higher (95% confidence interval = 27%-72%) after intussusception compared with the general population of the same age. Age, sex, age at intussusception, and time since intussusception did not modify risk of tonsil disease. The risks of acute tonsillitis, chronic disease of the tonsils, and tonsillectomy were equally increased after intussusception.Intussusception was associated with an increased risk of tonsil disease in childhood. Children with a general tendency to lymphoid hyperplasia may be at increased risk of intussusception. [ABSTRACT FROM AUTHOR]

High parity is associated with reduced risk of ovarian cancer. One hypothesis is that pregnancy is associated with clearance of a fraction of the genetically modified (premalignant) cells from the ovaries.We evaluated this hypothesis using a model that estimates the cell clearance fraction at first and second pregnancy according to age at pregnancy. The model was fitted using reproductive history data from a cohort of 1.5 million Danish women born between 1935 and 1978 and followed for 28.7 million person-years. During this follow-up period, 2,035 developed invasive ovarian cancer.We found the model to have a satisfactory fit despite the very few parameters involved. The model estimated similar cell clearance fractions for the first and second pregnancy and decreasing clearance with later age at pregnancy.The relation of pregnancy history to risk of ovarian cancer can be well described by a cell clearance model that allows the cell clearance fraction to decrease with age at pregnancy. [ABSTRACT FROM AUTHOR]

Background: Smaller studies have reported a higher offspring risk of congenital heart defects (CHDs) for mothers with CHDs than for fathers with CHDs. In a large population-based study, we investigated whether offspring risk of CHD differed for mothers and fathers with CHDs., Methods: All people born in Denmark, 1977 to 2011, with at least 1 registered parent, were included in our cohort (n=2 341 061). Parent-child recurrence of CHDs was evaluated using risk ratios (RRs) comparing risks of CHDs in individuals with and without a parent with a CHD, estimated using log-linear binomial regression., Results: The RRs for any CHD in offspring were 5.39 (95% CI, 4.88-5.96) for mothers and 3.04 (95% CI, 2.59-3.57) for fathers affected with any CHD; the ratio of RRs for mothers versus fathers was 1.82 ( P <0.0001). Recurrence RRs for the same cardiac phenotype in parent and offspring were significantly stronger for mothers than for fathers for conotruncal defects (ratio of RRs, 4.98), left ventricular outlet tract obstruction (ratio of RRs, 4.98), and ventricular septal defects (ratio of RRs, 2.51) but not for atrioventricular septal defects (ratio of RRs, 1.06). Birth rates among people with CHDs, relative to the general population, were 18% higher for women than for men, regardless of parental cardiac phenotype., Conclusions: Recurrence risks of CHDs were significantly greater in the offspring of affected women than in the offspring of affected men. The excess maternal recurrence risks could not be explained by the slightly higher birth rates in women with CHDs.

Background: Knowledge of the familial contribution to congenital heart diseases (CHD) on an individual and population level is sparse. We estimated an individual's risk of CHD given a family history of CHD, as well as the contribution of CHD family history to the total number of CHD cases in the population., Methods and Results: In a national cohort study, we linked all Danish residents to the National Patient Register, the Causes of Death Register, the Danish Central Cytogenetic Register, and the Danish Family Relations Database, yielding 1 763 591 persons born in Denmark between 1977 and 2005, of whom 18 708 had CHD. Individuals with CHD were classified by phenotype. We estimated recurrence risk ratios and population-attributable risk. Among first-degree relatives, the recurrence risk ratio was 79.1 (95% confidence interval [CI] 32.9 to 190) for heterotaxia, 11.7 (95% CI, 8.0 to 17.0) for conotruncal defects, 24.3 (95% CI,12.2 to 48.7) for atrioventricular septal defect, 12.9 (95% CI, 7.48 to 22.2) for left ventricular outflow tract obstruction, 48.6 (95% CI, 27.5 to 85.6) for right ventricular outflow tract obstruction, 7.1 (95% CI, 4.5 to 11.1) for isolated atrial septal defect, and 3.4 (95% CI, 2.2 to 5.3) for isolated ventricular septal defect. The overall recurrence risk ratio for the same defect was 8.15 (95% CI, 6.95 to 9.55), whereas it was 2.68 (95% CI, 2.43 to 2.97) for different heart defects. Only 2.2% of heart defect cases in the population (4.2% after the exclusion of chromosomal aberrations) were attributed to CHD family history in first-degree relatives., Conclusions: Specific CHDs showed highly variable but strong familial clustering in first-degree relatives, ranging from 3-fold to 80-fold compared with the population prevalence, whereas the crossover risks between dissimilar cases of CHD were weaker. Family history of any CHD among first-degree relatives accounted for a small proportion of CHD cases in the population.