Genes Behind Stuttering Found

LiveScience Staff

Date: 10 February 2010 Time: 12:00 PM ET

FOLLOW US

SHARE

The epigenome is a molecular marking system that controls gene expression without altering the DNA sequence. In a sense, the epigenome is the genome's boss. Image CREDIT: Dreamstime

Stuttering may have genetic underpinnings, according to a new study. For the first time, scientists have identified specific genetic alterations that they believe play a key role in giving rise to the speech disorder.

These alterations, or mutations, are located on three particular genes, and are thought to cause a glitch in the way cells dispose of cellular "garbage."

"For hundreds of years, the cause of stuttering has remained a mystery for researchers and health care professionals alike, not to mention people who stutter and their families," said Dr. James F. Battey, Jr., director of the National Institute on Deafness and Other Communication Disorders (NIDCD), the organization that led the study. "This is the first study to pinpoint specific gene mutations as the potential cause of stuttering," and might lead to an expansion in treatment options, he said.

The results were published online Feb. 10 in the New England Journal of Medicine.

Stuttering is a speech disorder in which a person repeats or prolongs sounds, syllables, or words, disrupting the normal flow of speech. The result can severely hinder communication. Most children who stutter outgrow it, although many do not; roughly 1 percent of adults stutter worldwide. Current therapies for adults who stutter have focused on such strategies as reducing anxiety, regulating breathing and rate of speech, and using electronic devices to help improve fluency.

Stuttering tends to run in families, and researchers have long suspected a genetic component. Previous studies of a group of families from Pakistan pointed to chromosome 12 as a site that may be involved in the disorder. (A chromosome is a long sequence of DNA that contains many genes.)

In the current study, researchers took a closer look at this chromosome. They identified mutations in a gene known as GNPTAB in the affected family members. The GNPTAB gene is carried by all higher animals, and gives cells instructions for making an enzyme that assists in breaking down and recycling cellular components.

They then analyzed the genes of 123 Pakistani individuals who stutter — 46 from the original families and 77 who are unrelated — as well as 96 unrelated Pakistanis who don't stutter, and who served as controls. Individuals from the United States and England also took part in the study, 270 who stutter and 276 who don't. The researchers found some individuals who stutter possessed the same mutation as that found in the large Pakistani family.

The scientists then looked at two other genes which are closely tied to the role of GNPTAB. They found individuals who stuttered showed mutations in these genes while control groups did not.

Several of the newly identified "stuttering genes" are thought to contribute to certain metabolic disorders. People with these disorders cannot properly break down cell waste, causing deposits to build up in their cells. These deposits can ultimately cause health problems in the body's joints, skeletal system, heart and liver, as well as developmental problems in the brain. They are also known to cause problems with speech.

So why don't people who stutter also have these metabolic disorders? For many of these metabolic diseases, a person needs to have two defective copies of a gene, said study author Dennis Drayna, a geneticist with the NIDCD. But in the current study, nearly all of the unrelated individuals who stuttered had only one copy of the mutated gene, he said.

The findings open new research avenues into possible treatments for stuttering. For example, current treatment methods for some metabolic disorders involve injecting a manufactured enzyme into a person's bloodstream to replace the missing enzyme. The researchers wonder if enzyme replacement therapy might be a possible method for treating some types of stuttering in the future.

Right now, about 9 percent of people who stutter are known to possess mutations in one of the three genes, the researchers say. Next, they plan to conduct a worldwide study to better determine the number of people who carry these mutations. A long-term goal is to better understand how metabolic defects may affect structures within the brain that are essential for fluent speech.

The Genetics of Eye Color

A person's eye color is determined by the genes inherited from their parents. The types of alleles received from the parents are assigned to certain chromosomes. The dominant genes are expressed and the recessive genes are hidden. In the development of the iris those genes tell enzymes to produce and place a certain amount of melanin in the iris to form the eye color.

Eye Color Calculator

1) First, select the Parents' eye colors:   Eye Color of Mother:   Eye Color of Father: 2) Now select the parents' eye color genes: Mother's Genes:   Brown/Blue gene     Green/Blue gene   Father's Genes:   Brown/Blue gene     Green/Blue gene   3) And then:  (press again for more children). Brown eyed Children: Green eyed Children: Blue eyed Children:

So what is going on here?

 

(An explanation for our interactive eye color genetics calculator)

• Eye colors are distinct (brown, green, blue) rather than mixed. If we mixed green and blue paints we would get a greenish-blue paint. Mixing in brown would give mud. Eye colors of children came out as pure green, blue, or brown, not as a mixture of the colors of their parents' eyes.
• Eye color acts like distinct particles are inherited - one can have the particle for green eyes or the particle for blue eyes.
• Children can have different eye colors than either of their parents. This is strange, if colors can't mix. It would make sense if colors mixed and blue and green eyed parents had greenish-blue eyed children.
• Brown tends to swamp out green, green tends to swamp out blue.
• A parent with brown-brown genes produces only children with brown eyes, but a parent with brown-blue eyes could produce children with eye colors other than brown.

Genes are structures that are carried on larger structures called chromosomes. The genes for each characteristic come in pairs, and the two genes together produce a given characteristic. One of the genes of the pair came from the father and the other came from the mother.

An individual with brown and blue alleles of the bey2 gene on chromosome 15. There are two copies of chromosome 15. Each copy has the bey2 gene. On one copy the bey2 gene is in the brown flavor, in the other the bey2 gene is in the blue flavor. The difference between the brown and blue alleles is due to some difference in the genetic code for each gene (the DNA sequence for the bey2 gene isn't yet known).

Genes are particles that get inherited.
Humans have several eye color genes. Two of these genes are named bey2 (brown eye) and gey (green eye).
Genes come in flavors called alleles.
The bey2 gene has two flavors - brown and blue.
The gey gene also has two flavors - green and blue.
Genes are on chromosomes. There is one copy of the gene on each chromosome (some genes also come in many copies).
Chromosomes come in pairs.
Thus each individual has two copies of each gene. These two copies can be the same flavor (allele) or different flavors.

Genes are used to produce proteins. A gene that comes in two flavors might come in one flavor where the protein works correctly and another flavor in which the protein does not work. Thus an individual with one copy of the good flavor and one copy of the defective flavor for a gene could still produce a protein that worked.

Treatments offer hope in fighting AML cancer

A friend of ours has a form of leukemia called “AML”. He’s currently receiving chemotherapy, but not doing well. Do you know of any hospitals where they may be doing research to find a cure for this cancer? – T.H., Philadelphia
Dear T.H.: Acute Myelogenous Leukemia, also referred to as “AML,” is a cancer of the blood in which immature, abnormal white blood cells grow rapidly and uncontrollably in the bone marrow and interfere with the bone marrow’s ability to produce red blood cells, healthy white blood cells and platelets. It’s a fairly rare cancer, with men affected more often than women. The average age of someone diagnosed with AML is 63 years of age. AML cell growth is very fast and aggressive, and it’s a fatal disease within weeks or months if not treated or diagnosed promptly.
Because AML cell growth crowds out normal blood cells, it typically causes anemia and the associated symptoms of fatigue and shortness of breath from a reduction in oxygen-carrying red blood cells; bruising or bleeding from a reduction in platelets (clot cells); and infection from a reduction in normal white blood cells.
The key to survival in AML is early diagnosis, chemotherapy to try to induce remission and eventual stem cell transplantation.
There are several subtypes of AML, and treatment and prognosis varies among the subtypes. Five-year survival rates vary from 15-70 percent, and relapse rates vary from 33-78 percent, depending upon the subtype.Exciting research from England’s Institute of Cancer Research may have found a novel treatment for AML using tranylcypromine (Parnate), an old and rarely-used antidepressant. All-Trans Retinoic Acid (a vitamin A derivative) has worked to treat one particular form of leukemia by directing cancer cells to mature, age and die naturally. AML seems to be resistant to All-Trans Retinoic Acid because the genes in the cancer cells that it normally targets are shut off. Researchers just discovered that if they block an enzyme using the antidepressant tranylcypromine, they can switch on the genes that make AML cancer cells vulnerable to All-Trans Retinoic Acid. Researchers at Johns Hopkins University and the Medical University of South Carolina are collaborating with researchers in England, Germany and Canada.
I am a virile, sexually active, middle-aged man. Prior to engaging in sex, my partner and I enjoy imbibing in some alcoholic beverages to loosen up/set the mood. How is it that alcohol has a positive effect on achieving an erection? Would testosterone supplements help? – J.W., Lima, Ohio.
Dear J.W.: Alcohol, in moderate quantities, helps to reduce anxiety, stress and inhibition through its role as a central nervous suppressor.
Psychological impotence and performance anxiety can be helped by a modest amount of alcohol prior to initiating sex.
It can slow the heart rate and increase the activity of the parasympathetic nervous system – the nerves that regulate digestion, slow down the heart rate and increase the flow of blood into the penis and clitoris.
Dr. Mitchell Hecht is a physician specializing in internal medicine. Send questions to him at: “Ask Dr. H,” P.O. Box 767787, Atlanta, GA 30076. Personal replies are not possible.

Read more here: http://www.thenewstribune.com/2012/04/08/2099769/treatments-offer-hope-in-fighting.html#storylink=cpy