What genetic testing does California Cryobank currently perform on its donors?
Genetic Tests Currently Performed On Our Donors
If genetic screening for any of the following conditions reveals an abnormal result during the donor qualification process, that donor applicant would not be eligible to continue in our program. Sperm donor applicants are eligible to participate only if they have negative genetic test results. It is important to note that while a negative genetic test result reduces the chance of having a child with a specific genetic disorder, this negative result cannot eliminate the risk for birth defects in an individual's offspring.
Cystic Fibrosis Carrier Screening
Cystic fibrosis (CF) is a chronic illness that typically involves severe lung disease and gastrointestinal problems. People with CF often have a shortened lifespan. Cystic fibrosis is inherited in an autosomal recessive manner which means that both parents have to carry mutations for CF to be at risk of having a child affected with this disorder. CF occurs most often among individuals of Caucasian ancestry; approximately 1 out of every 25 healthy Northern European or Ashkenazi Jewish individuals carries a mutation for CF. Carrier screening for cystic fibrosis is performed by analyzing the donor's DNA for common mutations or changes in the gene for CF. CF carrier screening is performed on all of CCB's sperm donor applicants, regardless of the donor's ancestry.
Hemoglobin is the molecule that carries oxygen to the cells of our bodies. Hemoglobin disorders are inherited in an autosomal recessive manner. This means that a child must inherit mutations from both parents to be at risk of developing a disorder such as alpha-thalassemia, beta-thalassemia, or sickle cell anemia. A hemoglobin evaluation on our donor applicants includes a complete blood count (CBC) which evaluates the size, shape, and number of a person's blood cells. In addition, a test called a hemoglobin fractionation is performed to detect many, but not all, clinically significant differences in a person's hemoglobin.
- Alpha-Thalassemia and Beta-Thalassemia
Individuals who are affected with thalassemia generally have severe anemia and may require frequent blood transfusions and other medical interventions over the course of their lifetimes. Some types of thalassemia may result in a shortened lifespan; more severe forms may result in fetal demise or death in infancy. Alpha-thalassemia occurs most often among individuals of Asian or African ancestry. Beta-thalassemia (also known as Cooley's anemia or Mediterranean anemia) occurs most often among people of Mediterranean descent.
- Sickle Cell Anemia
Hemoglobin S is the hemoglobin that is found in abnormal amounts in a person who is affected with sickle cell anemia. Sickle cell anemia causes painful episodes of joint and bone pain and increased risks for strokes, infections, and organ damage. Approximately 1out of every 10 individuals of African descent carries a mutation for sickle cell anemia.
Chromosomes are the structures that carry our DNA. A chromosome analysis looks at the number and the structure of an individual’s chromosomes. Typically, an analysis of human chromosomes reveals a total of 46 chromosomes. If a sperm donor applicant has an abnormal chromosome numbers or structure he would not be eligible to participate in our program.
Spinal Muscular Atrophy Carrier Screening
Spinal muscular atrophy is a progressive neuromuscular disease that results in muscle wasting and, in its most common and severe form, death due to respiratory failure before two years of age. SMA is inherited in an autosomal recessive manner which means that both parents must be carriers of mutations for SMA to be at risk of having a child affected with this disorder. Approximately 1 out of every 50 individuals in the general population carries a mutation for SMA. California Cryobank began performing carrier screening for spinal muscular atrophy (SMA) on all active sperm donors and donor applicants in August 2008.
Additional genetic tests currently performed on donors with Jewish ancestry
The following disorders occur most often among individuals of Ashkenazi Jewish ancestry. Each of these conditions is inherited in an autosomal recessive manner which means that both parents have to carry mutations for the same condition to be at risk of having a child affected with that disorder. Carrier screening for these conditions is performed by analyzing the donor's DNA for common mutations that cause these conditions in the Ashkenazi Jewish population.
Bloom Syndrome Carrier Screening
Individuals affected with Bloom syndrome have growth problems, poor immune system function, and a high rate of cancer. Most affected individuals die from cancer before 30 years of age. The carrier frequency for Bloom syndrome is approximately 1 in 100 among individuals with Ashkenazi Jewish ancestry. California Cryobank began performing carrier screening for Bloom syndrome on Jewish donors in August 2008.
Familial Dysautonomia Carrier Screening
Familial dysautonomia is a disorder of the nervous system, characterized by insensitivity to pain, episodes of vomiting and sweating, and unstable blood pressure and body temperature. In addition, people with familial dysautonomia can have learning disabilities. The average life expectancy for someone with familial dysautonomia is approximately 30 years. The carrier frequency in the Ashkenazi Jewish population is approximately 1 in 30.
Fanconi Anemia Type C Carrier Screening
Symptoms of Fanconi anemia Type C include short stature, significant bone marrow problems, and heart, kidney, gastrointestinal, spinal, or limb defects. Lifespan may be shortened, as individuals with this condition have an increased risk for leukemia and other cancers. The carrier frequency in the Ashkenazi Jewish population is approximately1 in 89.
Gaucher Disease Carrier Screening
Symptoms of Gaucher disease include frequent fevers, bone pain and fractures, problems with blood clotting, anemia, seizures, and enlargement of the spleen and liver. The symptoms vary in age of onset and severity and may result in a shortened lifespan. Treatment for Gaucher disease is currently available for many affected individuals. The carrier frequency for Gaucher disease in the Ashkenazi Jewish population is approximately 1 in 12.
Mucolipidosis Type IV Carrier Screening
Mucolipidosis Type IV (MLIV) affects the development of the brain and nervous system beginning in the first year of life. There is no treatment for MLIV at this time. The carrier frequency for Mucolipidosis Type IV in the Ashkenazi Jewish population is approximately 1 in 120. California Cryobank began performing carrier screening for MLIV on Jewish donors in August 2008.
Niemann-Pick Disease Type A Carrier Screening
Individuals with Niemann-Pick disease Type A have enlargement of the liver and spleen with rapid neurological deterioration and death typically occurring by age 4. The carrier frequency for Niemann-Pick disease in the Ashkenazi Jewish population is approximately 1 in 90.
Tay-Sachs Disease Carrier Screening
Tay-Sachs disease (TSD) is a progressive neurological disorder that begins in infancy with the loss of developmental milestones and typically results in death by age 5. Tay-Sachs disease occurs most often among individuals with Ashkenazi Jewish or French Canadian ancestry. Approximately 1 out of every 30 individuals of Ashkenazi Jewish ancestry carries a mutation for TSD. Routine carrier screening for TSD is performed by enzyme analysis.