deafness – BioQuakes

Denis Rebrikov, A scientist in Russia has done research regarding ways in which he can edit the genome sequence of an embryo in order to prevent the fetus from developing certain gene mutations, specifically in this case a hearing problem or possible complete deafness. His plans are very controversial to some, who believe the possible risks of very harmful mutations to DNA that would be passed onto direct and future offspring, outweigh the possible benefits. However, some people find this scientific possibility to be worth the risk, if it means not passing a potentially very harmful gene down to offspring. If these methods are done correctly, it should alter the genome sequence in the embryo so that future offspring off that embryo will not inherit the negative mutation.

One couple shared their story in detail, in which both parties have a hearing deficiency, the man with partial deafness, and the woman completely deaf. Their biggest hope is to have children who will not inherit hearing issues, because of the apparent challenges they have had to face themselves because of them. They would be the first couple to perform this gene editing on an IVF embryo, so they obviously have some reservations. One of those being publicity, but more importantly the potential risks of using the CRISPR genome editor. They already have a daughter with hearing loss, but they never chose to test her genes for mutations, nor did they get her a cochlear implant to aid her hearing, because of the potential risks of that. When they finally tested her genes, they learned that she had the same common hearing loss mutation called 35delG in both her copies of a gene called GJB2. The parents then tested themselves, realizing they were both 35delG homozygous, meaning their daughter’s mutations were not unique to her, they had been inherited.

If either the mother or father had a normal copy of the GJB2 gene, a fertility clinic could have more easily created embryos by IVF and tested a few cells in each one to select a heterozygote–with normal hearing–to implant. At this stage, Denis Rebrikov informed them that CRISPR genome editing would be their only option. However, the process presents possibly deal breaking risks, such as mosaicism, in which a gene edit might fail to fix the deafness mutation, which could create other possible dangerous mutations like genetic disorders or cancer. The couple has not decided to go through with the editing just yet, but it is something they are open to in the future as more possible new research or test subjects become available.

Explaining the CRISPR Method: “The CRISPR-Cas9 system works similarly in the lab. Researchers create a small piece of RNA with a short “guide” sequence that attaches (binds) to a specific target sequence of DNA in a genome. The RNA also binds to the Cas9 enzyme. The modified RNA is used to recognize the DNA sequence, and the Cas9 enzyme cuts the DNA at the targeted location… Once the DNA is cut, researchers use the cell’s own DNA repair machinery to add or delete pieces of genetic material, or to make changes to the DNA by replacing an existing segment with a customized DNA sequence.” -US National Library of Medicine Genetics Home Reference

Woman with a hearing aid

If you had the opportunity to alter something in the gene’s of your baby’s embryo, would you? Under what circumstances would you consider this, and what risks might stop you from deciding to do it? Comment down below.

The solution to hearing loss: listening to things?

By marsupialniche

On December 4, 2015

In Student Post

When we think of hearing loss, we typically think that it’s because the person listens to too many loud things, and that they should try to give their ears a break by hearing as little as possible. However, according to researchers as Case Western Reserve, the solution to preventing deafness might be to use your ears.

Let me explain. There are tiny hairs in your ear (stereocilia) which allow you to hear by vibrating. When overly loud noise hits these hair bundles, they whip back and forth, damaging them. However, if they are constantly stimulated with gentle sound, the movement of the hair bundles actually allows them to readjust, repair, and maintain the health of the hairs of the inner ear. The researchers looked at zebrafish, whose hair bundles move back and forth constantly at amazing speeds, which reinforced the idea. In more detail, the proteins that constitute the hair bundles have a higher turnover rate when under stimulation, meaning that the proteins in your ear hairs are replaced more often, allowing the hair to repair itself. Ears not used much retain the useless broken proteins, leading to poor hearing. Ear hairs used a lot are like muscles when working out: yeah, they’re a bit torn, but they’ll be stronger when they grow back.

The research team says they haven’t proven stereocilia repair themselves, and that they still need to look into more detail for that process (link for the more academically inclined). However, the theory looks very promising.

I find it interesting that biological organisms have a tendency to heal through usage, as it almost seems counterproductive to me. I typically think of rest and recuperation when I think of healing, but apparently biology wants you to just keep on chuggin’. What other systems or things do you think we have that heal with use?

(But.

Quite simply.

To heal your hearing,

One needs to whip their hair back and forth.)

Gerbils Can You Hear Me?

By arthenice

On October 8, 2012

In Student Post

80 to 90 percent of people suffer from inherited deafness. In a study, scientists have reversed deafness in gerbils. This is a huge step in gene therapy research this month making the possibility of using gene therapy as a cure for deftness one step closer. Genetic therapy is the use of genetic material such as DNA to manipulate a cell and is generally used to treat inherited diseases; in this case scientists used human embryonic stem cells. The gerbils in the study were born deaf. This type of deafness is a birth defect caused by damage to hair cells in the inner ear. These inner ear hair along with auditory neurons which translate sound vibrations from the inner-ear cells to electrical signals are how you can hear. Scientists specifically worked on gerbils whose deafness was caused by a mutation in a gene coding for a protein called vesicular glumamate transporter-3. Even minor alterations to a protein’s primary structure ,such as the movement of a double bond, will cause major defects in the tertiary structure and the function of the protein. The mutated protein in this study vesicular glutamate transporter-3 controls the consumption of glutamate (neurotransmitter) into synaptic vesicles, which join two nerve cells, of the neural cells. This is clearly groundbreaking news this month and has proved the various use of stem cells. How do you feel about the use of embryonic stem cell research? Feel free to comment!!

BioQuakes

AP Biology class blog for discussing current research in Biology

Tag: deafness

Embryo Gene Editing can Ensure Offspring Do Not Inherit a Deafness Gene!

The solution to hearing loss: listening to things?

Gerbils Can You Hear Me?

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