Friday, February 29, 2008

No similiar warning is given to men even though risk of autism has seen a six-fold increase due to fatherhood over 40

Taken from butterfly-like network

motherhood later by kati at katalinlovasz dot net.
February 28th, 2008 by LK
Women over forty are having more and more babies in Britain, writes the Guardian (via Jezebel). Conception rates are rising among women and even men are increasingly becoming fathers at a later age. By contrast, a month ago the (also British) Independent wrote about how women should worry sooner than they do about their biological clock because trying for motherhood at a later age comes with all kinds of risks, complications, possible infertility, and all kinds of misery because women wait too long.

I’m going to believe the optimistic story, personally… And here’s why: the Independent’s report includes a couple of sentences about fatherhood at a later age also posing risks, such as a six-fold increase in autism among children of fathers over 40 (incidentally, the mother’s age is not a factor in an increased risk of autism). Yet this tidbit is conveniently buried in the report, and the only conclusion drawn is that women really need to start worrying about their age. In a deeply sexist move, no similar warning is given to men, even though, according to the article, older fatherhood also poses risks. Sexism has never struck me as particularly objective and I’m tired of the fear-mongering, especially given that, in reality, I don’t think people have as much choice as they like to think about when they have children.
In other news, my own older-woman’s-pregnancy (I’m 35) is progressing, albeit in a somewhat painful way: a few days ago Baby Girl found a way to position herself so that her head rests on a round ligament on my left side and what feels like one of her knees on a round ligament on my right side. Round ligaments are sensitive and having a head and a knee be supported by them is, shall we say, not the most pleasant sensation for me. Yet she seems to feel this is the perfect position for her, and when I manage to massage her into moving to a different spot, within minutes she settles herself right back. Preferably with a few well-placed kicks against my ribs, but I don’t mind those.

My pelvis is a cradle, literally.

I do have to confess I’m using this as an excuse to rest… instead of unpacking the dishes and books still in boxes after the move.

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Thursday, February 21, 2008

Don't be Fooled By The Teenagers Having Worse Birth Outcomes than 40 Plus

This study is not designed to see whether autism, schizophrenia, cancers, mental retardation, genetic defects increase with the age of the father at conception. What about comparing 20-30 year old outcomes by 1st grade with 40-60 years old by 1st grade. How much autism, and other developmental disabilities in each set?

From the new study:

" The study, the largest on the effects of paternal age on adverse birth outcomes, suggested that babies of teenage fathers are at an increased risk of having problems ranging from pre-term delivery or low birth weight, through to death in or near to the time of delivery, the Science Daily online reported."

"After adjusting for confounding factors (such as race, education, smoking and alcohol drinking during pregnancy, adequacy of prenatal care and the sex of the baby), the study found that babies born to teenage fathers (aged less than 20) were more likely to be born early (a 15 per cent increased risk), have low birth weight (13 per cent increased risk), be small for gestational age (17 per cent increased risk), have a low Apgar score (13 per cent increased risk) or to die within the first four weeks after birth (22 per cent increased risk) or to die in the period from four weeks to one year after birth (41 per cent increased risk). "

More Harmful Genetic Changes in DNA of European Americans than African Americans

African DNA has more genetic diversity
By Roger Highfield, Science Editor
Last Updated: 1:01pm GMT 21/02/2008

Human migration from Africa to Europe more than 30,000 years ago appears to have left its mark on the genes of Europeans today.

Schematic of worldwide human genetic variation, with colours representing different genetic types
The DNA of European-Americans appears to carry proportionately more harmful genetic changes than that of African-Americans, because they emerged from a smaller and less diverse population.

The study of 35 people, published in Nature by a team led by Prof Carlos Bustamante of Cornell University, New York State, shows that the proportion of single letter spelling variations in the human genetic code that are probably harmful and unique to that particular population are significantly higher in the European-Americans (16 per cent) than in the African-American sample (12 percent) his team analysed.

"What is happening at an individual level will vary tremendously within and among populations," stressses Prof Bustamante, explaining that the effect can only be seen in the population level and it is not known how these deleterious mutations affects disease risk.

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Wednesday, February 20, 2008

Where are some of the hidden problems for offspring of older dads found? In their CNVs deletions?????.

University of Michigan scientists and their colleagues at the National Institute on Ageing have produced the largest and most detailed worldwide study of human genetic variation, a treasure trove offering new insights into early migrations out of Africa and across the globe.

Like astronomers who build ever-larger telescopes to peer deeper into space, population geneticists like U-M's Noah Rosenberg are using the latest genetic tools to probe DNA molecules in unprecedented detail, uncovering new clues to humanity's origins.

The latest study characterises more than 500,000 DNA markers in the human genome and examines variations across 29 populations on five continents.

'Our study is one of the first in a new wave of extremely high-resolution genome scans of population genetic variation,' said Rosenberg, an assistant research professor at U-M's Life Sciences Institute and co-senior author of the study, to be published in the 21 February edition of Nature.

'Now that we have the technology to look at thousands, or even hundreds of thousands, of genetic markers, we can infer human population relationships and ancient migrations at a finer level of resolution than has previously been possible.'

The new study, led by Rosenberg and National Institute on Ageing colleague Andrew Singleton, produced genetic data nearly 100 times more detailed than previous worldwide assessments of human populations. It shows that:

- A recently discovered type of human genetic variation, known as a copy-number variant or CNV, is a reliable addition to the toolkit of population geneticists and should speed the discovery of disease-related genes. Rosenberg and his colleagues discovered 507 previously unknown CNVs, which are large chunks of DNA - up to 1,000,000 consecutive 'letters' of the genetic alphabet - that are either repeated or deleted entirely from a person's genome. Various diseases can be triggered by an abnormal gain or loss in the number of gene copies.

- It's sometimes possible to trace a person's ancestry to an individual population within a geographic region. While previous studies have found that broad-scale geographic ancestry could be successfully traced, the new results indicate 'it's becoming increasingly possible to use genomics to refine the geographic position of an individual's ancestors with more and more precision,' Rosenberg said.

- Human genetic diversity decreases as distance from Africa - the cradle of humanity - increases. People of African descent are more genetically diverse than Middle Easterners, who are more diverse than Asians and Europeans. Native Americans possess the least-diverse genomes. As a result, searching for disease-causing genes should require the fewest number of genetic markers among Native Americans and the greatest number of markers among Africans.

The results are being made available on publicly shared databases.

'I hope the study will be an invaluable resource for understanding genomic variability and investigating genetic association with disease,' said the NIA's Singleton.

The researchers analysed DNA from 485 people. They examined three types of genetic variation: single-nucleotide polymorphisms, or SNPs; haplotypes; and CNVs.

If the human genome is viewed as a 3-billion-letter book of life, then SNPs represent single-letter spelling changes, haplotype variations equate to word changes, and CNVs are wholesale deletions or duplications of full pages.

The patterns revealed by the new study support the idea that humans originated in Africa, then spread into the Middle East, followed by Europe and Asia, the Pacific Islands, and finally to the Americas.

The results also bolster the notion of 'serial founder effects,' meaning that as people began migrating eastward from East Africa about 100,000 years ago, each successive wave of migrants carried a subset of the genetic variation held by previous groups.

'Diversity has been eroded through the migration process,' Rosenberg said. In addition to his position at the Life Sciences Institute, Rosenberg is an assistant professor of human genetics, biostatistics, and ecology and evolutionary biology, as well as an assistant research professor of bioinformatics.

'This data set is so rich. It provides a much more comprehensive, cross-sectional snapshot of the human genome than previous studies,' said Paul Scheet, a post-doctoral researcher in the U-M Department of Biostatistics and one of the lead authors.

'The next step for these studies is to sequence whole genomes,' said Mattias Jakobsson, a post-doctoral researcher at the U-M Centre for Computational Medicine and Biology and another lead author. 'You would take 500 individuals, and you would just completely sequence everything, and then you'd have almost every important variant that's out there.'

The work was supported in part by National Institutes of Health grants, the U-M Centre for Genetics in Health and Medicine, the Alfred P. Sloan Foundation, the Burroughs Wellcome Fund, the National Centre for Minority Health and Health Disparities, and the Intramural Program of the National Institute on Ageing.

University of Michigan News Service press release.


Friday, February 01, 2008 and PreemiesWhy old men shouldn't impregnate young women

Older men are more likely to produce premature babies. For a mother 20 to 24 years old, the risk of bearing a child before 32 weeks' gestation almost doubles if the father is 45 to 49 years old rather than 25 to 29. The younger the mother, the stronger the effect. Previous studies have linked older fathers to some pregnancy complications, birth defects, and diseases in offspring. Interpretations: 1) Men may accumulate bad mutations as they age or are exposed to toxins. 2) Nature may discourage big age differences between parents because they're disadvantageous to the child. 3) For God's sake, she's young enough to be your daughter. (For Human Nature's take on polygamy, click here. For incest


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