Showing posts with label Genetics. Show all posts
Showing posts with label Genetics. Show all posts

Sunday, August 3, 2008

Ethnicity and Common Mutations

Statisticians and geneticists at institutes around the globe have been able to determine that certain CFTR mutations are more commonly associated with specific races and ethnicities. They have identified 24 mutations, all of which have become part of carrier screening as recommended by the American College of Obstetrics and Gynecologists (ACOG.) Studies have gone so far as to associate the mutations not only with ethnicities, but by geographical region as well.

Below is a list of the 24 common mutations for which carrier testing, prenatal and newborn screening is conducted. These are listed numerically and alphabetically, and not frequency of occurrence.

Not every ethnicity has the same mutations. In North America for example, researchers have identified only twenty-one occurrences of 711+1G- >T in a sample population of greater than 5,000 individual chromosomes. This means that the particular mutation is rather rare for Americans in the United States and Canada.

Interestingly, the DeltaF508 mutation is the most common mutation worldwide. This is why a majority of cystic fibrosis patients have 2 copies of the delta F508 gene—one from each carrier parent.

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For more information and a complete list of the statistics of ethnicity/region and CF mutations, visit http://www.genet.sickkids.on.ca/cftr/resource/rptTable1Full.html

Myth #1: Only Caucasians have the cystic fibrosis gene.


Fact: Although Caucasians and people of European descent are the ones most likely to have the CF gene, people of any ethnicity can have it. The statistics below show CF mutations* broken down by race and ethnicity.

Caucasian

Odds that both parents are carriers: 1 in 625

Chance of having a child with CF: 1 in 2500

Mutation detection by screening: 90%

Hispanic American

Odds that both parents are carriers: 1 in 2,100

Chance of having a child with CF: 1 in 8,500

Mutation detection by screening: 57%

African American

Odds that both parents are carriers: 1 in 4,200

Chance of having a child with CF: 1 in 17,000

Mutation detection by screening: 69%

Asian American

Odds that both parents are carriers: 1 in 8,100

Chance of having a child with CF: 1 in 32,400

Mutation detection by screening: unknown


* the most commonly known 25 mutations

These statistics and probabilities will be very different for mixed race couples. This data is based on Genetic Medicine 4(5):379-91. 2002.

Tuesday, May 13, 2008

What is BiPAP?

BiPAP stands for Bi-level Positive Airway Pressure. It is a breathing apparatus that helps people get more air into their lungs. The airways are kept open using a BiPAP machine. BiPAP machines are adjusted to dual settings so that the pressure of the air coming in on inspiration can be different from the pressure of the air being exhaled. This is beneficial because it allows the patient to get more air in and out of the lungs without having to exert a lot of muscle energy.

A person’s forced vital capacity (FVC) as determined by a Pulmonary Function Test is largely what determines if a BiPAP machine is necessary. BiPAP is often used for people who have experienced pneumothorax (or collapsed lung) and as a result have loss of ability of the air sacs at the outermost portions of the lungs.

BiPAPs are usually used while a person is sleeping. It is used for conditions other than just cystic fibrosis. Sleep apnea sufferers for example, are often fitted with a BiPAP machine and face mask. Unlike supplemental oxygen, BiPAP masks are worn so that they completely enclose the mouth and nose. Most manufacturers of BiPAP face masks have different models available and all are designed to be as comfortable as possible.

Tuesday, November 20, 2007

Newborn Screening for Cystic Fibrosis Offers Hope

Imagine how difficult it would be as a parent, to take your sick child from doctor to doctor, and none knew what was wrong. The doctors seem to think your baby is merely battling a stubborn cold, or has food allergies of some sort. You know that can’t be the correct diagnosis, so you exhaust yourself searching websites that describe your little one’s symptoms, but never can quite put your finger on anything that explains it. Then you find it.

Cystic fibrosis.

Cystic fibrosis is the most common genetic disease affecting the Caucasian population. It is caused by a mutation in a particular protein in a person's DNA. This mutation causes a malfunction in the sodium and chloride transport channels. As a result, large amounts of salt are secreted in the sweat of a person with cystic fibrosis. Additionally, the body produces abnormally thick, sticky mucus which creates problems for nearly every major body function, particularly the respiratory and digestive systems.

People with cystic fibrosis are prone to frequent bouts of pneumonia and other lung infections. This is because bacteria become easily trapped in the sticky mucus that blocks the airways. Airway clearance devices and preventive maintenance medications are typically used to avoid infection. Such methods include inhaled antibiotics, bronchodilators, aerosolized medications, and chest physiotherapy.

Digestive problems also arise due to the thick mucus in the intestines and around the pancreas. Pancreatic insufficiency results when the pancreas cannot secrete the necessary enzymes to break down food. Enzymatic supplements are taken orally to aid in digestion. However, even with the supplements, people with cystic fibrosis are typically malnourished because the mucus lining the intestines prevents major vitamins like A, D, E and K from being properly absorbed into the body.

Treatment of cystic fibrosis
Over the last two decades there have been incredible developments in the treatment and understanding of cystic fibrosis. Ongoing research and the development of new medications are enabling some cystic fibrosis patients to survive into adulthood-something that was virtually unheard of in the past. Unfortunately, a cure remains to be found. The Cystic Fibrosis Foundation reports that the mean life expectancy is a mere 36 years of age.

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You’re stunned as you read about it. It sounds so scary, but all the symptoms add up and are exactly what your child has been experiencing over the last year or more. Loose, greasy, smelly, bowel movements; persistent cough and recurring lung infections; digestive problems; failure to gain weight; those funny shaped fingers. The list goes on and you can hardly process it. You are frustrated that the doctors never even thought of testing your child for this monster disease, and you wonder how much damage may have already been done to your little one’s body. You are angry, confused and sad all at once and your only thought is to get your child tested for cystic fibrosis as soon as possible.

Now imagine the empowerment of knowing as soon as your baby was born, about the unique health care requirements he or she would need. You and the doctors could work together to devise a treatment plan that would ensure the best possible health and quality of life for your son or daughter. Instead of fear of the unknown, you are given hope for the future.

Mandatory newborn screening for cystic fibrosis is not yet widespread. As of June, 2007, only 38 (see list, below) states in the U.S., including Washington D.C., had mandatory screening programs in place. Although more are planned, they cannot be implemented soon enough.

States with Mandatory Cystic Fibrosis screening for Newborns

Alabama*
Alaska
Arizona*
California
Colorado
Connecticut
Delaware
District of Columbia
Florida
Georgia
Hawai'i
Illinois*
Iowa
Kentucky
Maryland
Massachusetts
Michigan*
Minnesota
Mississippi
Missouri*
Montana
Nebraska
New Hampshire
New Jersey
New Mexico
New York
North Dakota
Ohio
Oklahoma
Oregon
Pennsylvania
Rhode Island
South Carolina
South Dakota
Virginia
Washington
Wisconsin
Wyoming

* these states have not yet implemented their mandatory screening program

According to the Cystic Fibrosis Foundation, the nation’s largest provider of funding for CF research, “Early diagnosis allows for immediate intervention with specialized therapies” which “have been shown to result in improved height, weight and cognitive function, and also may help maintain respiratory function. The greatest long-term benefit of newborn screening and early intervention is an increased life expectancy fewer hospitalizations over the course of a CF patient’s lifetime.”


California is the most recent state to require mandatory screening in newborns. It is the hope of many that the remaining states will soon be on board with this potentially life-enhancing measure. The following states have yet to mandate a newborn screening process for CF:

Arkansas
Colorado
Idaho
Indiana
Kansas
Louisiana
Maine
Nevada
North Carolina
Tennessee
Texas
Utah
Vermont
West Virginia

If your state is one of those listed above, consider taking action. Let your legislators know that it's important to implement newborn screening for CF. Here's how you can make that happen.

1. Contact the state health department to find out if CF is being considered for newborn screening.

2. Call or write to your governor. Visit the Web site of National Governor's Association www.nga.org to learn how to contact your governor.

3. Call or write the state legislators. www.ncsl.org is the website listing all the contact information for your state.