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Center for Jewish Genetics blog

Fragile X Awareness Month: A Closer Look at X-Linked Disorders

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XY-Chromosomes

By Emily Reisler

Most of us can agree that summer months often feel fun and lighthearted. But each year, July serves a serious purpose, too: it is Fragile X awareness month. Fragile X is a genetic condition that causes intellectual disability and some physical changes. It typically affects males more often and more severely than females. To better understand this X-linked disorder, let’s take a closer look at sex-linked conditions: What are they? How do they differ from autosomal disorders? Why do they have varying effects on males and females?

Each human cell contains 46 chromosomes, which come in 23 pairs. Chromosomes contain our genes. For the first 22 pairs of chromosomes, known as the autosomes, males and females have two copies of each gene, one from mom and one from dad. To have an autosomal dominant disorder, an individual must inherit at least one mutated copy of a specific gene. To have an autosomal recessive disorder, an individual must inherit two mutated copies of a specific gene. Autosomal disorders, whether they be dominant or recessive, affect males and females alike. 

Known as the sex chromosomes, the 23rd pair is where males and females differ genetically: Females inherit two X chromosomes, one from each parent, while males inherit one X chromosome from their mother and one Y from their father. Though the X and Y chromosomes have some similar regions, they vary in size, shape, and gene content. Because of this genetic difference between males and females, sex-linked disorders affect the sexes at varying frequencies and severities. 

With two copies of all X-linked genes, females develop X-linked disorders less frequently than males. If a female inherits a mutated copy of a gene found on the X chromosome, chances are she inherited a working copy of the gene from the other parent. In that scenario, the female would not be affected by the disorder, but there is a chance she could pass down the genetic change to a child. On the other hand, it’s unlikely for males to be carriers of an X-linked condition without showing symptoms of the disorder. Because males do not have a second X chromosome, one mutated copy of a gene on the X chromosome can result in severe phenotypic consequences. 

Fragile X syndrome, the sex-linked focus of this month, affects approximately 1 in 4,000 males and 1 in 8,000 females.1 The disorder occurs when specific mutations arise in the FMR1 gene, which is located on the X chromosome. FMR1 mutations are the most commonly known genetic cause of intellectual disability and of autism spectrum disorders,2  and they also cause abnormal physical characteristics. Though no cure for Fragile X syndrome exists, early intervention and treatment can help manage symptoms.

In honor of this year’s Fragile X awareness month, I challenge you all to keep learning about this disorder and spread awareness to others. Together we can become more informed about our genes and our health, and we can help protect the health of future generations.

Have further questions? Contact our genetic counselor at the Sarnoff Center for Jewish Genetics for more information.

Sources:

[1] https://www.genome.gov/19518828/learning-about-fragile-x-syndrome/

[2] http://www.ucdmc.ucdavis.edu/welcome/features/2012-2013/08/20120822_fragile-X.html

Photo credit: https://www.flickr.com/photos/nihgov/28189336441/in/album-72157662951050375/ 

It's Been 5 Years Since SCOTUS Ruled Human Genes Cannot Be Patented. Our Genetic Counselor Reflects.

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BRCA1and2

By Rebecca Wang, MS, CGC

I remember when I first learned about the BRCA gene in one of my college genetics classes. We discussed that a mutation in the BRCA gene drastically increases a person’s risk for breast and ovarian cancer, and that there was a simple blood test that could help someone learn if they were born with such a mutation. At the time, a single laboratory held a patent on the BRCA gene and the corresponding genetic test. The price of a BRCA test was well over $2,000, which I found shocking. Here was a test that could help save lives, yet the price was prohibitive for so many people who could benefit from it.

In a landmark 2013 case, the Supreme Court ruled unanimously that human genes could not be patented. This freed up ownership of the BRCA test and was a huge victory for ensuring patient access to quality healthcare and allowing the medical community to further scientific advancements around the BRCA gene. The day after the Supreme Court decision, a number of other commercial laboratories started to advertise their offerings for BRCA testing. With more than one player in the market, the cost of testing quickly went down. 

This June marks the five-year anniversary of this landmark legal ruling. In the last five years, there have been rapid developments in our knowledge of cancer genetics and the breadth of testing options. The rise of direct-to-consumer (DTC) genetic tests has also made genetic testing more widely available than ever, including some tests that provide information about inherited cancer risk. However, DTC tests pose a new set of challenges when it comes to accessing genetic tests.

As a genetic counselor, I have always been an advocate for patient access to important genetic technologies. But I also caution people to remember that not all genetic tests are the same. Direct-to-consumer tests that you can order without a healthcare provider do not meet the same technical standards as clinical testing, and ultimately provide a much more limited picture of your health risk. In the era of Amazon Prime, it may seem like the most efficient option to order a BRCA test for yourself online. But I think I speak for many an online shopper when I say that putting something in your cart just because it is convenient at the time often ends in regret. Genetic testing is no different. Ordering a BRCA test online may seem convenient, but genetic tests can be quite complex, and you may be left with unanswered questions after you receive results. Learning information about your risk for cancer is empowering, but it can also be scary without the proper guidance and support.

Like with any important purchase, I recommend you do your research before you commit to taking any action, and the Sarnoff Center offers a wealth of resources to help. You can start by reviewing a statement from the Sarnoff Center Board of Directors that outlines four key points for community members to understand when considering direct-to-consumer testing. Another good first step is to meet with a healthcare provider who specializes in cancer risk assessment to discuss your options. Genetic counselors and other clinicians can help provide access to the most comprehensive testing that is tailored towards your personal and family health history, and can guide you with what to do about genetic testing results. In my opinion, access to genetic testing is something everyone has a right to, but access to quality genetic counseling about test results is equally important. 

Meet Emily, the Sarnoff Center Lewis Summer Intern

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EmilyReisler

By Emily Reisler

This summer I am thrilled to be joining the team at the Norton & Elaine Sarnoff Center for Jewish Genetics as part of the Lewis Summer Interns Program. Currently, I am an undergraduate at the University of Michigan, seeking my Bachelor’s of Business Administration at the Ross School of Business, and I am also completing the pre-med requisites necessary for medical school. On campus, I am a research assistant in an ongoing study called Growing Toddlers, I am an active member of the Chi Omega sorority, a member of Hillel’s freshmen outreach board, an avid pro-Israel advocate, a huge Wolverine football fan, among other things. In my free time, I love to walk, hike, hang out on the beach, or pretty much do anything outdoors. I look forward to working at the Sarnoff Center, writing blog posts, assisting on other projects, and helping further the organization’s mission!

Newborn Screening and Carrier Screening

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Newborn-Carrier-Screenings

Carrier and newborn screenings both offer families information about the risk of a child having an early-onset, potentially life-limiting disease. However, carrier screening provides information much earlier in the family planning process. Ideally done prior to conception, carrier screening helps couples understand their risk of having a child with a serious genetic condition as well as available options. Newborn screening is for the baby – rather than the parents – and performed after birth. Read on to better understand the differences between carrier and newborn screenings and what Jewish and interfaith couples should know.

What is carrier screening?

Carrier screening is an essential step in planning for a healthy family. While everyone carries 6-8 changes in their genes, some genetic changes are more common among people of the same ethnic background. There are more than 19 recessive conditions that are more common among Ashkenazi Jews. Carriers are healthy individuals but if two people are carriers for the same condition, their future children may be at risk.

Ideally, couples should get carrier screening prior to pregnancy to understand their risks and all options. Carrier screening can also be done during early stages of pregnancy. Understanding the risk of having an affected child before birth gives couples more time to prepare.

Read more about carrier screening.

What is newborn screening?

Newborn screening is a public health program that can identify babies who have certain early-onset, potentially serious diseases. After a baby is born, and before the baby is discharged from the hospital, a blood sample is obtained through a heel prick. This blood sample is then analyzed to determine if a newborn is at high risk for certain genetic, metabolic, or congenital conditions. Babies with positive newborn screening results require additional diagnostic testing to determine if they are truly affected with a disease. Newborn screening also includes a hearing test and a pulse oximetry test to assess the risk for critical heart defects.

By identifying babies who have a serious illness, newborn screening allows for prompt follow up and early diagnosis. In many cases, early interventions and preventive measures can reduce symptoms, or even stop them before they begin. Ensuring that newborns with potentially life-threatening conditions get the treatment they need early on in life can have a major impact on improving long term health outcomes.

All babies born in the United States receive newborn screening. The programs are mandated by state law, and the conditions screened for vary slightly from state to state.

Do carrier screening and newborn screening test for the same conditions?

There is some overlap between diseases found on carrier screening panels and diseases that are part of newborn screening. Both include many recessive genetic conditions and metabolic disorders; however, there are some key differences. Some of the conditions on newborn screening, such as congenital heart disease, do not have a universal genetic cause and are not part of routine carrier screening. On the other hand, large expanded carrier screening panels may include a significantly higher number of conditions than newborn screening panels.  

Both newborn screening and carrier screening provide information about risk for genetic disorders, but do not provide an actual diagnosis. Newborn screening may detect that an infant has a disorder. Individuals with positive newborn screen results will be referred to a specialist for counseling and diagnostic testing to determine if the condition is truly present. Couples who have had negative carrier screening may already know they are at low risk for having a child with some of the newborn screening diseases before their baby is tested

What diseases are included as part of newborn screening?

Every state has a newborn screening program, although the conditions they screen for vary by state. Diseases included on newborn screening panels are early-onset and life-limiting, and some are potentially fatal. For diseases that are treatable, starting treatments early can impact the course of the disease. Newborn screening typically includes conditions from the following groups of disorders:

  • Amino acid disorders
  • Fatty acid oxidation disorders
  • Organic acid disorders
  • Lysosomal storage disorders
  • Other metabolic disorders, such as galactosemia and biotinidase deficiency
  • Hemoglobin disorders, such as sickle cell disease and thalassemia
  • Endocrine disorders (hypothyroidism and adrenal insufficiency)
  • Cystic fibrosis
  • Hearing loss
  • Critical congenital heart disease

Baby's First Test provides more information about these diseases. 

Newborn screening panels do not screen for all genetic diseases. Sometimes, healthcare providers recommend additional testing based on family history or other risk factors. It is important to make your doctor aware of any diseases you are concerned about your child inheriting in order to determine if they should be tested after birth.

For more information about newborn screening in your state, visit http://www.babysfirsttest.org/newborn-screening/states.

Individuals in Illinois can also find information about newborn screening on the Illinois Department of Public Health website

What else do Jewish and interfaith couples need to know about these screenings?

Diseases on newborn screening are not selected for individuals based on ethnic risk. Conditions on newborn screening affect infants of any background, and are not specific to one ethnicity. Some, but not all, Jewish genetic disorders are included on newborn screening and conditions vary depending on what state your child is born in.

Carrier screening can provide more information about a couple’s risk of having a child with a Jewish genetic disorder. Many screening programs for Jewish and interfaith couples, including the one offered by the Norton & Elaine Sarnoff Center for Jewish Genetics, screen for conditions that are more commonly found among Jews as well as pan-ethnic conditions that are found equally across people of all backgrounds. For more information about carrier screening, visit jewishgenetics.org/cjg/Carrier-Screening.aspxor contact the Sarnoff Center.

 

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Affordable, Accessible Genetic Screening in Illinois

Our affordable, accessible carrier screening program uses advanced technology to provide comprehensive screening for Jewish and interfaith couples. Visit our Get Screened page to learn more and register.