Identification of common mutations in the CFTR gene. Note: Carrier screening on healthy children will generally not be performed.
Performing Laboratory / Facility
UCLA Medical Center Clinical Laboratory (CHS)
Performing Section
Molecular Pathology
Availability
Monday through Friday, 0700-1700
Turnaround Time
14 days from receipt of specimen in performing lab
Methodology
The GenMark eSensor technology uses a solid-phase electrochemical method for determining the genotyping status of the defined panel of CF mutations. Purified genomic DNA is isolated from the patient specimen according to defined laboratory procedures and is amplified in a multiplex PCR reaction using specific primers and enzyme. The amplified DNA is converted to single stranded DNA via exonuclease digestion and is then combined with a single buffer containing a pair of ferrocene-labeled, allele-specific oligonucleotide signal probes for each variant. The mixture of amplified sample and signal buffer is loaded onto the eSensor cartridge, which contains single-stranded oligonucleotide capture probes bound to gold-plated electrodes. The cartridge is inserted into the XT-8TM instrument where the single-stranded targets first hybridize to the matched signal probes and then hybridize to the complementary sequences of the capture probes. The genotype of each polymorphism is determined by voltammetry, which generates specific electrical signals from the ferrocene-labeled allele-specific signal probes. This genotyping test does not identify all possible mutations in CFTR. This assay only tests for the 23 mutations recommended in the ACMG/ACOG guidelines for CF population carrier screening.
Use
Identification of common mutations in an affected patient, assessing carrier risk for an individual planning a pregnancy or relatives of affected patients, prenatal diagnosis, identification of mutations in an infertile male with a diagnosis of congenital bilateral absence of the vas deferens, work-up for male infertility, prenatal diagnosis of a fetus with echogenic bowel, and population carrier screening.
Limitations
The eSensor CF Genotyping Test does not identify all possible mutations in the CFTR gene. A negative result for all the mutations in this panel does not necessarily indicate that the individual does not carry mutations in the CFTR gene. The mutations included in this test represent >80% of the mutations carried by Caucasian American adults. More than 1,500 mutations have been identified in the CFTR gene with varying confidence that they cause cystic fibrosis. When present in the same region as a panel mutation, they may interfere with genotyping results.
Additional Information
Cystic fibrosis (CF) is the most common lethal autosomal recessive disorder among Caucasians of northern European ancestry and the most common genetic cause of infant mortality. CF is found less frequently in other racial and ethnic groups. The heterozygote (carrier) frequency among Caucasians in the United States is approximately 1 in 29. CF is characterized by one or more clinical features that vary in severity, including a progressive decline of pulmonary function secondary to chronic lung infections, exocrine pancreatic insufficiency and elevated chloride concentration in sweat. Almost all males with CF are sterile due to congenital bilateral absence of the vas deferens. Affected newborns may present with meconium ileus. These clinical manifestations of CF are the result of abnormally viscous mucous secretions from glands and duct epithelia, leading to infection. The basic defect causing this disease remains unknown. Diagnosis of CF is based on carefully defined clinical criteria, analysis of sweat chloride concentration, and mutation analysis. In 2001, the American College of Medical Genetics and the American College of Obstetricians and Gynecologists established a standard of care that all pregnant couples and those planning a pregnancy be offered carrier screening for the 25 most common CFTR mutations, and the panel was revised in 2004 to a total of 23 mutations after the removal of two variants (1078delT and I148T). The test described here is suitable for that purpose. For individuals who are negative for mutations by targeted mutation testing, DNA sequence analysis of the entire CFTR coding region is available as a sendout test. Genetic consultation with the laboratory directors is available.
Identification of common mutations in the CFTR gene. Note: Carrier screening on healthy children will generally not be performed.
Performing Laboratory / Facility
UCLA Medical Center Clinical Laboratory (CHS)
Performing Section
Molecular Pathology
Availability
Monday through Friday, 0700-1700
Turnaround Time
14 days from receipt of specimen in performing lab
Methodology
The GenMark eSensor technology uses a solid-phase electrochemical method for determining the genotyping status of the defined panel of CF mutations. Purified genomic DNA is isolated from the patient specimen according to defined laboratory procedures and is amplified in a multiplex PCR reaction using specific primers and enzyme. The amplified DNA is converted to single stranded DNA via exonuclease digestion and is then combined with a single buffer containing a pair of ferrocene-labeled, allele-specific oligonucleotide signal probes for each variant. The mixture of amplified sample and signal buffer is loaded onto the eSensor cartridge, which contains single-stranded oligonucleotide capture probes bound to gold-plated electrodes. The cartridge is inserted into the XT-8TM instrument where the single-stranded targets first hybridize to the matched signal probes and then hybridize to the complementary sequences of the capture probes. The genotype of each polymorphism is determined by voltammetry, which generates specific electrical signals from the ferrocene-labeled allele-specific signal probes. This genotyping test does not identify all possible mutations in CFTR. This assay only tests for the 23 mutations recommended in the ACMG/ACOG guidelines for CF population carrier screening.
Use
Identification of common mutations in an affected patient, assessing carrier risk for an individual planning a pregnancy or relatives of affected patients, prenatal diagnosis, identification of mutations in an infertile male with a diagnosis of congenital bilateral absence of the vas deferens, work-up for male infertility, prenatal diagnosis of a fetus with echogenic bowel, and population carrier screening.
Limitations
The eSensor CF Genotyping Test does not identify all possible mutations in the CFTR gene. A negative result for all the mutations in this panel does not necessarily indicate that the individual does not carry mutations in the CFTR gene. The mutations included in this test represent >80% of the mutations carried by Caucasian American adults. More than 1,500 mutations have been identified in the CFTR gene with varying confidence that they cause cystic fibrosis. When present in the same region as a panel mutation, they may interfere with genotyping results.
Additional Information
Cystic fibrosis (CF) is the most common lethal autosomal recessive disorder among Caucasians of northern European ancestry and the most common genetic cause of infant mortality. CF is found less frequently in other racial and ethnic groups. The heterozygote (carrier) frequency among Caucasians in the United States is approximately 1 in 29. CF is characterized by one or more clinical features that vary in severity, including a progressive decline of pulmonary function secondary to chronic lung infections, exocrine pancreatic insufficiency and elevated chloride concentration in sweat. Almost all males with CF are sterile due to congenital bilateral absence of the vas deferens. Affected newborns may present with meconium ileus. These clinical manifestations of CF are the result of abnormally viscous mucous secretions from glands and duct epithelia, leading to infection. The basic defect causing this disease remains unknown. Diagnosis of CF is based on carefully defined clinical criteria, analysis of sweat chloride concentration, and mutation analysis. In 2001, the American College of Medical Genetics and the American College of Obstetricians and Gynecologists established a standard of care that all pregnant couples and those planning a pregnancy be offered carrier screening for the 25 most common CFTR mutations, and the panel was revised in 2004 to a total of 23 mutations after the removal of two variants (1078delT and I148T). The test described here is suitable for that purpose. For individuals who are negative for mutations by targeted mutation testing, DNA sequence analysis of the entire CFTR coding region is available as a sendout test. Genetic consultation with the laboratory directors is available.
