And you thought men could father babies at any age. Seems as if the older they get, the more they face an increased risk of fathering children with abnormalities like autism and schizophrenia.
It Seems the Fertility Clock Ticks for Men Too
Posted by Jill Fallon at February 27, 2007 8:21 AM | TrackBack | PermalinkWonder why the Nina Rabin's article did not mention that 35 is the age when offspring are statistically significantly more likely to suffer from a genetic disorder.
Eur Psychiatry. 2007 Jan;22(1):22-6. Epub 2006 Dec 4. Links
Paternal ages below or above 35 years old are associated with a different risk of schizophrenia in the offspring.Wohl M, Gorwood P.
INSERM U675, 16 rue Henri Huchard 75018 Paris, France; AP-HP (Paris VII), C.H.U Louis Mourier, Service de psychiatrie du Professeur Ades, 178 rue des Renouillers, 92701 Colombes Cedex, France.
BACKGROUND: A link between older age of fatherhood and an increased risk of schizophrenia was detected in 1958. Since then, 10 studies attempted to replicate this result with different methods, on samples with different origins, using different age classes. Defining a cut-off at which the risk is significantly increased in the offspring could have an important impact on public health. METHODS: A meta-analysis (Meta Win((R))) was performed, assessing the mean effect size for each age class, taking into account the difference in age class references, and the study design. RESULTS: An increased risk is detected when paternal age is below 20 (compared to 20-24), over 35 (compared to below 35), 39 (compared to less than 30), and 54 years old (compared to less than 25). Interestingly, 35 years appears nevertheless to be the lowest cut-off where the OR is always above 1, whatever the age class reference, and the smallest value where offspring of fathers below or above this age have a significantly different risk of schizophrenia. CONCLUSION: No threshold can be precisely defined, but convergent elements indicate ages below or above 35 years. Using homogeneous age ranges in future studies could help to clarify a precise threshold.
also
"It makes sense that the mutations causing these diseases would occur more frequently in older men, and indeed that's what we saw for Apert syndrome," says Ethylin Jabs, M.D., director of the Center for Craniofacial Development and Disorders at Johns Hopkins.
Importantly, disorders linked to advancing paternal age begin to increase rapidly at about the same time as maternal risks increase -- age 33 to 35. Until now, the only evidence for paternal age effects has come from determining how many children with these diseases are born to fathers of various ages.
To obtain the first genetic explanation for these effects, the scientists studied sperm from about 60 men of various ages and looked for two genetic changes responsible for 99 percent of the cases of Apert syndrome. They found that men over 50 were, on average, three times as likely as men under 30 to have sperm with at least one of these changes. The mutations were not more common in blood samples as men aged.
The scientists say it's likely that the number of cell divisions that go into making a sperm plays a large role in the link between Apert syndrome and paternal age, and represents a fundamental difference between how aging egg and sperm can impact the health of a child.
"In the men we studied, these mutations had not been inherited, but rather collected over time in the reservoir of primitive cells that become sperm," says first author Rivka Glaser, a graduate student in human genetics at the Johns Hopkins School of Medicine.
Cells that mature into eggs are essentially frozen in time from puberty until the time the egg is signaled to develop. Because of the stage at which they are "frozen," the most likely error in an egg is to have an abnormal partitioning of chromosomes, producing an egg with an extra copy or a missing copy, Glaser says. For example, in Down syndrome, an extra copy of chromosome 21 is inherited from the mother.
Sperm, on the other hand, are continually produced throughout a male's lifetime from a reservoir of primitive cells. These primitive cells, like other kinds of so-called stem cells, can either replicate themselves or take a step closer to becoming a sperm, a process called differentiation. All told, these cells divide every 21 days after puberty, and at each cell division the opportunity exists for an error in copying the DNA.
"Literally hundreds of millions of sperm are made in each batch, so in most cases there are still many normal sperm available," says Jabs, also a professor of pediatrics. Their study showed that "high levels" of mutations among men who had no children with Apert syndrome amounted to roughly 3 sperm with the mutation among 100,000 sperm.
If an error is made in any of the steps toward becoming a sperm, the only cells affected are the resulting sperm for that batch. However, if an error appears in a primitive cell as it replicates itself and the mistake isn't fixed, the mutation will continue to be passed on to all of its progeny, including subsequent primitive cells and other batches of semen.
As men age, more of these primitive cells have collected mutations that cause Apert syndrome, leading to more sperm with the mutations in each batch of semen, the scientists suggest. The risk of having a child with Apert is about six times higher for a man age 52 than for someone who's 27.
Authors on the study are Glaser, Jabs, and Rebecca Schulman, of Johns Hopkins School of Medicine, and Karl Broman, of the Johns Hopkins Bloomberg School of Public Health.
Note: This story has been adapted from a news release issued by Johns Hopkins Medical Institutions.
also
. "As a major influence on new mutations in the human gene pool is related to the advancing age of fathers, Dr. Malaspina first examined the relationship of schizophrenia and paternal age. Data showed a strong escalation in schizophrenia risk as the age of the father increased, accounting for over a quarter of the schizophrenia cases. Another of her studies found that fathers of sporadic schizophrenia cases were 5 years older than familial case fathers. If sporadic schizophrenia can originate from new mutations, then neurodevelopmental genes are reasonable candidates. Her study will examine if patients with sporadic schizophrenia, particularly those with fathers older than 35 at birth, show features found in other neurodevelopmental diseases that correlate with paternal age, such as craniofacial abnormalities, nonspecific cognitive deficits and delayed developmental milestones."
also
Dr. Leslie B. Raschka wrote:
"Eight articles reporting on 10,347 patients described increased prevalence of mental illness as related to older paternal age.
Conclusions: The age of the father is an important determinant of the health of future generations. Children conceived by fathers older than 36 years of age are at increased risk for genetic illness due to recent mutation in the male germ cell.
The genetic illness of a child could originate in a mutation related to the age of the father or to a mutation in the spermatogenesis caused by ageing in previous generations. The ageing process in the male is an important, probably the most important, cause of genetic illness in human populations."
What good is an article that tells the public that men in their mid forties to late forties are at increased risk when it is true of men by their mid thirties that are at increased risk.
Studies have found that many men are increased risk of having offspring with damaged genes controlling brain cell development even before 35.
In a study published in 2004 is was noted that
The link between schizophrenia and older paternity had been made before, but this was the first large study to look at a range of factors that could confound the results, said Professor John McGrath, a psychiatric epidemiologist at the Queensland Centre for Mental Health Research.
"If all babies had fathers less than 30, the paper suggests, the incidence of schizophrenia would reduce by 15 per cent," he said.
also
A recent study revealed that sperm in men older than 35 showed more DNA damage than that of men in the younger age group. In addition, the older men's bodies appeared less efficient at eliminating the damaged cells, which could pass along problems to offspring.
"When you talk about having children, there has been a lot of focus on maternal age," said Narendra Singh, research assistant professor in the UW Department of Bioengineering and lead researcher on the study. "I think our study shows that paternal age is also relevant."
Wonder why the Nina Rabin's article did not mention that 35 is the age when offspring are statistically significantly more likely to suffer from a genetic disorder.
Eur Psychiatry. 2007 Jan;22(1):22-6. Epub 2006 Dec 4. Links
Paternal ages below or above 35 years old are associated with a different risk of schizophrenia in the offspring.Wohl M, Gorwood P.
INSERM U675, 16 rue Henri Huchard 75018 Paris, France; AP-HP (Paris VII), C.H.U Louis Mourier, Service de psychiatrie du Professeur Ades, 178 rue des Renouillers, 92701 Colombes Cedex, France.
BACKGROUND: A link between older age of fatherhood and an increased risk of schizophrenia was detected in 1958. Since then, 10 studies attempted to replicate this result with different methods, on samples with different origins, using different age classes. Defining a cut-off at which the risk is significantly increased in the offspring could have an important impact on public health. METHODS: A meta-analysis (Meta Win((R))) was performed, assessing the mean effect size for each age class, taking into account the difference in age class references, and the study design. RESULTS: An increased risk is detected when paternal age is below 20 (compared to 20-24), over 35 (compared to below 35), 39 (compared to less than 30), and 54 years old (compared to less than 25). Interestingly, 35 years appears nevertheless to be the lowest cut-off where the OR is always above 1, whatever the age class reference, and the smallest value where offspring of fathers below or above this age have a significantly different risk of schizophrenia. CONCLUSION: No threshold can be precisely defined, but convergent elements indicate ages below or above 35 years. Using homogeneous age ranges in future studies could help to clarify a precise threshold.
also
"It makes sense that the mutations causing these diseases would occur more frequently in older men, and indeed that's what we saw for Apert syndrome," says Ethylin Jabs, M.D., director of the Center for Craniofacial Development and Disorders at Johns Hopkins.
Importantly, disorders linked to advancing paternal age begin to increase rapidly at about the same time as maternal risks increase -- age 33 to 35. Until now, the only evidence for paternal age effects has come from determining how many children with these diseases are born to fathers of various ages.
To obtain the first genetic explanation for these effects, the scientists studied sperm from about 60 men of various ages and looked for two genetic changes responsible for 99 percent of the cases of Apert syndrome. They found that men over 50 were, on average, three times as likely as men under 30 to have sperm with at least one of these changes. The mutations were not more common in blood samples as men aged.
The scientists say it's likely that the number of cell divisions that go into making a sperm plays a large role in the link between Apert syndrome and paternal age, and represents a fundamental difference between how aging egg and sperm can impact the health of a child.
"In the men we studied, these mutations had not been inherited, but rather collected over time in the reservoir of primitive cells that become sperm," says first author Rivka Glaser, a graduate student in human genetics at the Johns Hopkins School of Medicine.
Cells that mature into eggs are essentially frozen in time from puberty until the time the egg is signaled to develop. Because of the stage at which they are "frozen," the most likely error in an egg is to have an abnormal partitioning of chromosomes, producing an egg with an extra copy or a missing copy, Glaser says. For example, in Down syndrome, an extra copy of chromosome 21 is inherited from the mother.
Sperm, on the other hand, are continually produced throughout a male's lifetime from a reservoir of primitive cells. These primitive cells, like other kinds of so-called stem cells, can either replicate themselves or take a step closer to becoming a sperm, a process called differentiation. All told, these cells divide every 21 days after puberty, and at each cell division the opportunity exists for an error in copying the DNA.
"Literally hundreds of millions of sperm are made in each batch, so in most cases there are still many normal sperm available," says Jabs, also a professor of pediatrics. Their study showed that "high levels" of mutations among men who had no children with Apert syndrome amounted to roughly 3 sperm with the mutation among 100,000 sperm.
If an error is made in any of the steps toward becoming a sperm, the only cells affected are the resulting sperm for that batch. However, if an error appears in a primitive cell as it replicates itself and the mistake isn't fixed, the mutation will continue to be passed on to all of its progeny, including subsequent primitive cells and other batches of semen.
As men age, more of these primitive cells have collected mutations that cause Apert syndrome, leading to more sperm with the mutations in each batch of semen, the scientists suggest. The risk of having a child with Apert is about six times higher for a man age 52 than for someone who's 27.
Authors on the study are Glaser, Jabs, and Rebecca Schulman, of Johns Hopkins School of Medicine, and Karl Broman, of the Johns Hopkins Bloomberg School of Public Health.
Note: This story has been adapted from a news release issued by Johns Hopkins Medical Institutions.
also
. "As a major influence on new mutations in the human gene pool is related to the advancing age of fathers, Dr. Malaspina first examined the relationship of schizophrenia and paternal age. Data showed a strong escalation in schizophrenia risk as the age of the father increased, accounting for over a quarter of the schizophrenia cases. Another of her studies found that fathers of sporadic schizophrenia cases were 5 years older than familial case fathers. If sporadic schizophrenia can originate from new mutations, then neurodevelopmental genes are reasonable candidates. Her study will examine if patients with sporadic schizophrenia, particularly those with fathers older than 35 at birth, show features found in other neurodevelopmental diseases that correlate with paternal age, such as craniofacial abnormalities, nonspecific cognitive deficits and delayed developmental milestones."
also
Dr. Leslie B. Raschka wrote:
"Eight articles reporting on 10,347 patients described increased prevalence of mental illness as related to older paternal age.
Conclusions: The age of the father is an important determinant of the health of future generations. Children conceived by fathers older than 36 years of age are at increased risk for genetic illness due to recent mutation in the male germ cell.
The genetic illness of a child could originate in a mutation related to the age of the father or to a mutation in the spermatogenesis caused by ageing in previous generations. The ageing process in the male is an important, probably the most important, cause of genetic illness in human populations."
What good is an article that tells the public that men in their mid forties to late forties are at increased risk when it is true of men by their mid thirties that are at increased risk.
Studies have found that many men are increased risk of having offspring with damaged genes controlling brain cell development even before 35.
In a study published in 2004 is was noted that
The link between schizophrenia and older paternity had been made before, but this was the first large study to look at a range of factors that could confound the results, said Professor John McGrath, a psychiatric epidemiologist at the Queensland Centre for Mental Health Research.
"If all babies had fathers less than 30, the paper suggests, the incidence of schizophrenia would reduce by 15 per cent," he said.
also
A recent study revealed that sperm in men older than 35 showed more DNA damage than that of men in the younger age group. In addition, the older men's bodies appeared less efficient at eliminating the damaged cells, which could pass along problems to offspring.
"When you talk about having children, there has been a lot of focus on maternal age," said Narendra Singh, research assistant professor in the UW Department of Bioengineering and lead researcher on the study. "I think our study shows that paternal age is also relevant."