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Genetic Screening

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Genetic Screening 2017-07-04T08:25:50+00:00

Preconception Genetic Screening

Houston IVF strongly recommends genetic screening for any patient who is attempting to get pregnant.

What is genetic screening?

Genetic screening is the examination of an individual’s chromosomes, genes, proteins and/or other analytes for alterations associated with genetic disorders or conditions. The specific type of genetic screening recommended is based on your family history, self-reported ancestry, and/or your personal medical history.

What is genetic screening used for?

Genetic screening in this context is used to determine whether you are at an increased risk of having a child with a particular genetic disorder (carrier screening).

What are the limitations or risks regarding genetic screening?

The genetic screening will not identify all genetic abnormalities. It is specific for only the particular disorder that is being tested. Additionally, as with all testing, it does not provide 100% accuracy. The physical risks associated with genetic testing are typically small, especially as the tests we order typically require only a blood sample or a cheek swab. In some cases, genetic tests can also reveal previously unknown information about family relationships such as non-paternity or undisclosed adoption. Some patients have concerns about financial consequences of genetic testing such as the potential for discrimination or loss of employment or insurance. In May of 2008, the Genetic Information Nondiscrimination Act was signed into federal law. This offers protection against genetic discrimination in health insurance and employment.

What if I have further questions?

The following genetic counselors are available to provide you with more information regarding appropriate genetic screening:

  • Jennifer Hoscovek with University of Texas 713-500-6383 or 832-325-7133 option 2
  • Sandra Darilek with Baylor College of Medicine 713-799-1930.

Which screening tests are recommended for me?

  • Cystic Fibrosis – Cystic fibrosis is a disorder characterized by pulmonary and gastrointestinal manifestations of varying severity. Although there is a wide spectrum of clinical expression most individuals who have CF experience substantial morbidity and reduced life expectancy. The carrier frequency is 1:29 among Caucasians, 1:46 among Hispanics, 1:62 among African-Americans, and 1:90 among Asian-Americans.
  • Spinal Muscular Atrophy – This is a group of inherited diseases that cause progressive muscle degeneration and weakness, eventually leading to death. One in fifty people carry this gene.
  • Fragile X Syndrome – Fragile X syndrome is a genetic condition involving changes in part of the X chromosome. It is the most common form of inherited intellectual disability (mental retardation) in boys. Screening is recommended to those with a family history of: fragile X, undiagnosed mental retardation, developmental delay or autism. Screening is also recommended for women that have been diagnosed with ovarian insufficiency, and some groups recommend universal screening.
  • Ashkenazi Jewish Panel – this is a panel including multiple disorders such as Canavan disease, Gaucher disease, Tay-sachs, Fanconi anemia, etc. These disorders are most prevalent in individuals of Ashkenazi Jewish descent.
  • Hemoglobinopathy – this is a broad group of disorders involving abnormalities of hemoglobin, the oxygen-carrying protein of the red blood cells. This screening is recommended for individuals of African American, Asian, Mediterranean, Middle Eastern and/ or Hispanic descent.
  • Sickle Cell Disease – Sickle cell disease refers to a group of disorders involving abnormal hemoglobin. It occurs most commonly in people of African origin. Approximately 1:12 African Americans have sickle cell trait. This screening includes a hemoglobin electrophoresis.
  • Karyotype – A karyotype is the characterization of chromosomes based on size, shape and number. This is typically recommended in couples that have experienced multiple miscarriages, repeated IVF failures, or a woman diagnosed with premature ovarian failure. It is also recommended in men with significantly diminished sperm counts or azospermia (no sperm in the ejaculate).
  • Y Chromosome Microdeletion – A Y-chromosome microdeletion screen is a test a test to determine if there is a portion of the Y chromosome that is missing. The incidence of Y chromosome microdeletions among men with significant sperm abnormalities is between 4-18%. A male with a Y-chromosome microdeletion is typically asymptomatic, although will often have sperm abnormalities. If a male with a Y- chromosome microdeletion conceives a son, his son will likely also demonstrate sperm abnormalities.

Optional Screening

  • Good Start – offers a state-of-the art laboratory with a menu of tests that would be recommended by your doctor.
  • Counsyl Screening – a company that offers genetic screening for over 100 of the most common autosomal recessive genetic abnormalities.

Carrier Screening Overview

Ethnicity   CF Fragile X SMA Sickle Cell Alpha thal Beta thal Ashkenazi Panel Tay-Sachs
Caucasian √* √*
African American √* √*
Ashkenazi Jewish √* √*
Asian √* √*
Mediterranean √* √*
Hispanic √* √*
French Canadian/Cajun √* √*
Native American √* √*
√* Universal screening recommended by the American College of Medical Genetics; but recommended “per indication” by the American College of OBGYN

References
American College of Obstetricians and Gynecologists Practice Bulletin Hemoglobinopathies in Pregnancy Number 78, January 2007
Joint SOGC-CCMG Clinical Practice Guideline for Carrier Screening for Thalassemia and Hemoglobinopathies in Canada No. 218, October 2008.
American College of Obstetricians and Gynecologists Preconception and Prenatal Carrier Screening for Cystic Fibrosis: Clinical and Laboratory Guidelines October 2001
American College of Medical Genetics and Genomics http://www.acmg.net accessed 2012

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