Mother's milk is OK, even for the in-between babies

“Stop feeding him milk right away – just to be safe” was not what a new mother wanted to hear. The call came several days after Tamara Caspary gave birth to fraternal twins, a boy and a girl. She and husband David Katz were in the period of wonder and panic, both recovering and figuring out how to care for them. “A nurse called to ask how my son was doing,” says Caspary, a developmental Read more

Focus on mitochondria in schizophrenia research

Despite advances in genomics in recent years, schizophrenia remains one of the most complex challenges of both genetics and neuroscience. The chromosomal abnormality 22q11 deletion syndrome, also known as DiGeorge syndrome, offers a way in, since it is one of the strongest genetic risk factors for schizophrenia. Out of dozens of genes within the 22q11 deletion, several encode proteins found in mitochondria. A team of Emory scientists, led by cell biologist Victor Faundez, recently analyzed Read more

Fetal alcohol cardiac toxicity - in a dish

Alcohol-induced cardiac toxicity is usually studied in animal models; a cell-culture based approach could make it easier to study possible interventions more Read more

Department of Human Genetics

Cilia = not silly

Please check out the news story on “Cilia guide neuronal migration in  developing brain,” illustrating the dynamic role played by cilia. Cilia are tiny hair-like structures on the surfaces of cells, but in the brain they are acting more like radio antennae.

In developing mouse embryos, Emory and UNC researchers were able to see cilia extending and retracting as neurons migrate. The cilia appear to be receiving signals needed for neurons to find their places.

The Developmental Cell paper is here. As a bonus, we have a video featuring two of the paper’s authors, geneticist Tamara Caspary and “Neurotypical?” blogger Laura Mariani, a graduate student in Caspary’s lab.

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Flexibility and forgiveness during embryonic development

Geneticist Tamara Caspary’s laboratory has a recent paper in the journal Development showing how a developing mammalian embryo can correct a mispatterned neural tube over time. Former Genetics + Molecular Biology graduate student Chen-Ying Su, now a postdoctoral fellow at the Fred Hutchinson Cancer Research Center in Seattle, is the first author of the paper.

A molecule called “Sonic Hedgehog” is needed for proper patterning of the brain, spinal cord and eyes – it provides signals to the cells in the embryo, telling them what to become. Mutations that enhance Sonic Hedgehog signaling can lead to neural tube defects, some of the most common birth defects in humans, while those that diminish it can lead to holoprosencephaly, malformations of the brain and face. However, the majority of neural tube defects such as spina bifida do not come solely as a result of genetics – doctors think that getting enough (and possibly, not too much) of the B vitamin folic acid can prevent most of them.

Red = motor neuron precursor, green = later motor neuron marker
Mutation of Arl13b causes expansion of motor neurons (B and J)
Later deletion causes temporary expansion (C), corrected two days later (K)

Su and her colleagues examined mouse development in a situation where patterning of the neural tube is disrupted for a short time, because of a deletion in a gene (Arl13b), which helps to carry out Sonic Hedgehog’s instructions.

If Arl13b is not working starting from the beginning of development, embryos have an expansion of motor neurons, at the expense of other types of cells. The mutation leads to an open neural tube as well as abnormal eye, heart and limb development. However, if the deletion of Arl13b occurs on the ninth day, the embryo can recover proper patterning over the next few days. Mouse pregnancies last roughly three weeks.

Caspary says that while the relationship between Hedgehog signaling and neural tube defects is complicated, her lab’s recent work “does help define the time window during which we could non-surgically correct neural tube defects in utero.”

“In addition, it points to the importance of what we call “plasticity”- that cells can make incorrect decisions and correct them if still in a competency window, much like we think of adolescence,” she says. “It hints at the promise of stem cell research, that cells might be coaxed into other fates even though they start expressing tissue-specific markers. And it shows that the embryo is still much better at it than we are in a tissue culture dish.”

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The face behind a case

Last week Emory posted a news item about a case report published in the American Journal of Human Genetics. The paper described how geneticists at Emory, in cooperation with Sanford Burnham Medical Research Institute in San Diego, used “whole exome sequencing” — a sort of executive summary scan of the genome — to find the cause of a metabolic disease in a young boy.

The case was an illustration of the trend of whole exome sequencing, which is starting to enter clinical practice as a diagnostic technology. A photo of the patient, courtesy of his parents and Sanford Burnham, is a powerful reminder that within every case report, there’s a real person’s history.

Courtesy of Heather Buschman

“Over the years, we’ve come to know many families and their kids with glycosylation disorders. Here we can tell them their boy is a true ‘trail-blazer’ for this new disease,” says Hudson Freeze, director of the Genetic Disease program at Sanford Burnham. “Their smiles—that’s our bonus checks.”

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