The article “Older Dads More Likely to Have Kids with Autism” discusses the health effects of children inheriting genetic mutations from fathers above 45 years. The author highlights autism as one of the main outcomes of late fatherhood following the release of the results of a study involving the counting of the mutations corresponding to a father’s age at the time of conception.
The author presents the conclusions from the study, which shows a positive correlation between a father’s age and birth of children with harmful genetic mutations. The author highlights a direct relationship in the number of mutations carried by a child and the father’s age.
The article claims that paternal factors play the main role in influencing the occurrence of disorders relating to impaired development of neural functions in children (Diament, 2014). The author counters the view that old mothers are mainly responsible for the manifestation of autism in children. An evaluation of the results from studies on cases of autism in children fathered by men of different ages illustrates the effects of advanced paternal age on the risks of autism.
Case Studies on Advanced Paternal Age and Autism
An analysis of the data from a study on the role of paternal and maternal age in increasing the risk of autism spectrum disorder (ASD) illustrates the relationship between advanced paternal age and ASD. The study relied on a sample from 10 study sites in the US earmarked for investigation by the Center for Disease Control. The study used registers detailing the complete paternal information of about 250, 000 newborns.
The study presents about 1000 cases of children below eight years suffering from ASD whose paternal information shows risks of autism (Lamb et al., 2000). The study concludes that children fathered by men above 40 years have three times the likelihood of developing ASD compared to the third and later children fathered by men below 40 years. The researchers controlled factors such as the maternal age and education and prenatal environment to increase the sensitivity of the experiment.
A study on the influence of parental age on neurodevelopment disorders conducted on Jewish participants illustrates the relationship between paternal age and ASD. The study involves establishing a pattern connecting paternal age and cases of ASD in children born with a scope of six consecutive years. Information on the parental age of a subset of the study population confirms the details from the registry of Internal Classification of Diseases, which identifies about 110 cases of autism in the subset under study (Durkin et al., 2008).
The study concludes that there exists a significant association between paternal age and the probability of autism in a child. The study affirms that children fathered by men above 45 years have five times the probability of developing autism compared to children fathered by individuals below 30 years. The evaluation of the role of paternal age involves the control of factors such as maternal age and socioeconomic factors to increase the sensitivity of the findings.
The study of a birth group of ten years in Sweden used information from the National Patient Register to establish the relationship between paternal age and recorded cases of autism.
The study evaluates the manifestation of autism in children from 660 families born within the cohort. The researchers combined data on epidemiological experiments to reach the conclusion that children fathered by men above 50 years had 2.2 times the probability of developing autism compared to children fathered by men below 35 years (O’roak et al., 2011).
Discussion of the Case Studies on Autism
The expression of gene mutations in autism manifests as a primary gene defect or secondary effect in cells primarily in the brain and central nervous system, which leads to the observable characteristics of autism. The pervasive expression of a gene mutation may induce a chain effect that alters the phenotype of the affected cell.
An evaluation of the studies on autism risks due to advanced paternal age highlights the connection between biological mechanisms such as de novo aberrations and genetic mutations, which are responsible for increased changes in genetic imprinting in aging men. The fact that the studies involved participants from different settings helped to minimize the effects of localized environmental, socioeconomic and maternal factors on the identified cases of autism due to advanced paternal age.
The focus on analyzing the influence of paternal age on ASD arose due mixed results from experiments on the role of maternal age in the development of autism. Numerous studies have shown consistent results regarding the relationship between conditions such the Down syndrome and the influence of maternal age on chromosomal abnormalities.
The lack of congruency in five epidemiological experiments on the relationship between maternal age and ASD encouraged scientists to shift their focus to the effects of paternal age on neural developmental disorders.
An analysis of the reports on the prevalence of ASD illustrates a connection in the trend relating to child psychopathology and changes in the mean maternal and paternal age. Genome sequencing to establish the rate of de novo mutations in men of different ages provides insights on the linear relationship between paternal age and the average number of mutations that children can inherit from their fathers.
The frequency of de novo mutations increases with age and is double in men above 40 years compared to men below 25 years. The rate in de novo mutations reaches up to ten times the average rate in young men when men reach 80 years. The transmission of de novo mutations during conception creates the relationship between advanced paternal age and autism.
An analysis of the DNA structure illustrates that the sperm cell is under constant division and generation, which leads to frequent mutations. On the other hand, the harmonized nature of the egg cell in women minimizes the risks of autism due to inherited mutations with the advancement in maternal age. A study in Iceland on mutations in children that did not exist in either parent provided results on the percentage of mutations due to spontaneous changes in the sperm or embryo.
The study shows that fathers pass on 55 mutations to their children compared to 14 mutations inherited from women. With 50 percent of active genes having a key role in the neural development of a child, old fathers introduce random DNA errors, which have a high likelihood of affecting the development of the brain. Although most of the mutations are harmless, the implications of paternal age on autism risks remain significantly strong.
Scientists have identified a link between de novo mutations and alteration of the dopamine neurotransmitter, which leads to the manifestation of hyperactivity and other symptoms in individuals with autism. Mutation in the dopamine transporter gene affects the regulation of dopamine levels, which induces common behavioral effects evident in autism patients.
An experiment on the relationship between copy number variation (CNV) of the de novo mutations and ASD illustrates that 12 out of 118 individuals with ASD exhibited de novo CNVs. The results of the experiment show that about 3 percent of the participants had siblings affected by autism.
Conclusion
The increasing evidence on the influence of paternal age on autism risks requires education and awareness on the importance of early fatherhood. The fact that a 36 years old father will pass about twice the number of mutations passed by a 20 years old father highlights the importance of interventions to lower the mean paternal age.
The agreement among diverse studies on the extra mutations passed on to children with the advancement in paternal age has substantiated the fact that paternal age plays a greater role in influencing neurodevelopment disorders in children compared to maternal age. The study highlights the risks of delaying parenthood, which increases the susceptibility of children to inheriting a large number of mutant and harmful genes.
The evidence on the risks of advanced paternal age and the role of the sperm in complex neural developments supports the conclusion that genetic mutations in the sperm cells leads to about 30 percent of all autism cases. Despite the increase in the evidence on the role of advanced paternal age in autism, it is important to acknowledge other factors that lead to autism considering that a reasonable number of young fathers have children suffering from autism.
References
Diament, M. (2014). Older Dads More Likely To Have Kids with Autism, Disability Scoop. Web.
Durkin, M., Maenner, M., Newschaffer, C., Lee, L., Cunniff, C., Daniels, J., et al. (2008). Advanced Parental Age and the Risk of Autism Spectrum Disorder. American Journal of Epidemiology, 168(11), 1268-1276.
Lamb, J., Moore, J., Bailey, A., & Monaco, A. (2000). Autism: recent molecular genetic advances. Human Molecular Genetics, 9(6), 861-868.
O’roak, B. J., Shendure, J., Girirajan, S., Schwartz, J. J., Vives, L., Lee, C., et al. (2011). Exome sequencing in sporadic autism spectrum disorders identifies severe de novo mutations. Nature Genetics, 43(6), 585-589.