Ordering the Correct Genetic Test
Ordering the Correct Genetic Test
An advanced practice credentialed genetic nurse (APNG) was contacted by J.M., a 26-year-old single mother, about obtaining genetic testing for a known family mutation in the MSH2 gene, which is one of the genes associated with the HNPCC syndrome also known as Lynch syndrome. Such a mutation is associated with an 80% lifetime risk for developing colorectal cancer and a 70% chance of developing endometrial cancer, as well as other cancers (Lindor, McMaster, Lindor, & Greene, 2008). J.M. was uninsured and travelled more than 140 miles for the services, all of which were to be covered by charitable funding for the uninsured. The patient was carefully instructed prior to the appointment to bring a copy of the test results from any known relative who had tested positive for the mutation. J.M. said that she understood this request and would do so.
The patient arrived at the appointment with a copy of test results from a first cousin who had tested negative for the known mutation. The APNG explained that she would be unable to order the test that day because the policy was to order a test off of a positive result. J.M. was upset and frustrated because she had driven a great distance and said that her other relatives had simply gone to their doctors and had saliva tests ordered without any requirements. A pedigree was constructed, which J.M. perceived as unnecessary because a known mutation in the family had already been established. She was instructed that the pedigree was necessary for identifying other family members that might benefit from testing. Information from the pedigree helped determine that a paternal uncle had been the first to be tested and that J.M.'s father had died of colon cancer at age 57 years. Another living paternal aunt had tested negative, as did two female cousins (the daughters of the previously mentioned paternal uncle). The report that J.M. had brought was from one of the cousins.
The patient received pretest counseling on the implications of testing for this mutation and was informed that, assuming her father was an obligate carrier, she had a 50% chance of having the mutation. J.M. was instructed to return with a copy of the positive test result and the APNG explained that, although simply ordering the test and sending the specimen off of the negative test result J.M. brought to the appointment would be easier, the possibility that the wrong test would be ordered meant that it could not be done.
J.M. sent a copy of the positive test result about a week later. The uncle with the positive test result had a mutation in the MSH2 1215 gene; however, the negative test result for J.M.'s cousin was determined to be for the MSH2 1216 gene. The wrong test had been ordered for the cousin at some point, probably as a result of a copying error or that the handwriting on the test request form was illegible. The tests for the other cousin and the aunt were then reviewed and it became apparent that both of the cousins had undergone testing for the wrong mutation. The aunt's test had been correctly ordered. The mistake apparently occurred when one of the cousin's tests was incorrectly ordered from the aunt's report. The other cousin's test was ordered by a different primary care physician, but it was ordered off of her sister's test. The APNG realized this error and arranged for the two cousins to be retested for the correct mutation. One came back negative and one, unfortunately, was positive. The cousin who tested positive was devastated as she thought she was negative and no additional screening or prophylactic surgery would be needed after she had originally received the negative results. The positive test came with recommendations for annual colonoscopy and upper endoscopy, aggressive gynecologic screening, and potentially a prophylactic hysterectomy in the next 10 years. The cousin's colonoscopy was negative and she had not suffered any notable physical problems; however, psychological distress certainly occurred after the wrong test was ordered and adequate genetic counseling and support were not provided.
Regarding J.M., she did return for the test, had the correct mutation sequenced, and received a negative result. However, the cousin who tested positive required many hours of follow-up. Although J.M. would not have suffered harm from having the test ordered from the negative results she had originally brought in, this case demonstrates the potential risks of not ordering the correct test.
Case Study
An advanced practice credentialed genetic nurse (APNG) was contacted by J.M., a 26-year-old single mother, about obtaining genetic testing for a known family mutation in the MSH2 gene, which is one of the genes associated with the HNPCC syndrome also known as Lynch syndrome. Such a mutation is associated with an 80% lifetime risk for developing colorectal cancer and a 70% chance of developing endometrial cancer, as well as other cancers (Lindor, McMaster, Lindor, & Greene, 2008). J.M. was uninsured and travelled more than 140 miles for the services, all of which were to be covered by charitable funding for the uninsured. The patient was carefully instructed prior to the appointment to bring a copy of the test results from any known relative who had tested positive for the mutation. J.M. said that she understood this request and would do so.
The patient arrived at the appointment with a copy of test results from a first cousin who had tested negative for the known mutation. The APNG explained that she would be unable to order the test that day because the policy was to order a test off of a positive result. J.M. was upset and frustrated because she had driven a great distance and said that her other relatives had simply gone to their doctors and had saliva tests ordered without any requirements. A pedigree was constructed, which J.M. perceived as unnecessary because a known mutation in the family had already been established. She was instructed that the pedigree was necessary for identifying other family members that might benefit from testing. Information from the pedigree helped determine that a paternal uncle had been the first to be tested and that J.M.'s father had died of colon cancer at age 57 years. Another living paternal aunt had tested negative, as did two female cousins (the daughters of the previously mentioned paternal uncle). The report that J.M. had brought was from one of the cousins.
The patient received pretest counseling on the implications of testing for this mutation and was informed that, assuming her father was an obligate carrier, she had a 50% chance of having the mutation. J.M. was instructed to return with a copy of the positive test result and the APNG explained that, although simply ordering the test and sending the specimen off of the negative test result J.M. brought to the appointment would be easier, the possibility that the wrong test would be ordered meant that it could not be done.
J.M. sent a copy of the positive test result about a week later. The uncle with the positive test result had a mutation in the MSH2 1215 gene; however, the negative test result for J.M.'s cousin was determined to be for the MSH2 1216 gene. The wrong test had been ordered for the cousin at some point, probably as a result of a copying error or that the handwriting on the test request form was illegible. The tests for the other cousin and the aunt were then reviewed and it became apparent that both of the cousins had undergone testing for the wrong mutation. The aunt's test had been correctly ordered. The mistake apparently occurred when one of the cousin's tests was incorrectly ordered from the aunt's report. The other cousin's test was ordered by a different primary care physician, but it was ordered off of her sister's test. The APNG realized this error and arranged for the two cousins to be retested for the correct mutation. One came back negative and one, unfortunately, was positive. The cousin who tested positive was devastated as she thought she was negative and no additional screening or prophylactic surgery would be needed after she had originally received the negative results. The positive test came with recommendations for annual colonoscopy and upper endoscopy, aggressive gynecologic screening, and potentially a prophylactic hysterectomy in the next 10 years. The cousin's colonoscopy was negative and she had not suffered any notable physical problems; however, psychological distress certainly occurred after the wrong test was ordered and adequate genetic counseling and support were not provided.
Regarding J.M., she did return for the test, had the correct mutation sequenced, and received a negative result. However, the cousin who tested positive required many hours of follow-up. Although J.M. would not have suffered harm from having the test ordered from the negative results she had originally brought in, this case demonstrates the potential risks of not ordering the correct test.
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