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Genetics and Primary Care PowerPoint Presentation

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This medical PowerPoint presentation tells how genetics plays an important role in primary care. Primary care physicians (PCPs) are often the first point of contact for patients seeking medical care, and they play a crucial role in identifying patients who may be at risk for genetic conditions and referring them to appropriate specialists for further testing, diagnosis, and treatment.

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Published on : Mar 27, 2023 | Views : 1138 | Downloads : 0

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Slide 1-

Genetics and Primary Care What’s New in Prenatal Genetic Screening
Slide 2-

Genetics in Medicine: the 21st Century The Human Genome Project has brought inherited health factors to the forefront Genetic risk assessment, screening and testing is becoming part of primary medical care Clinical genetics and primary care need to work together to offer appropriate services
Slide 3-

We Are Working Together Risk assessment for common genetic conditions likely to be performed in the primary care/prenatal setting Screening and testing for genetic conditions increasingly performed in primary care/prenatal care Patients with rare or more complex genetic conditions, risks, or family histories likely continue to be served by genetics specialists
Slide 4-

Outline Preconception/prenatal genetic risk assessment and screening Family/personal history questionnaire Ethnicity-based screening Maternal serum screening and ultrasound How, When, Where to refer patients Resource Information
Slide 5-

Family History Questionnaire Screens for reproductive genetic risks Appropriate for patients considering pregnancy or already pregnant Contains referral guidelines for genetic services
Slide 6-

Assessment Areas Maternal age Family medical history (both sides) Current pregnancy/pre-pregnancy history Ethnic background (both sides)
Slide 7-

Maternal Age Maternal age 35 or older at time of delivery: increased risk for chromosome abnormalities Options for prenatal testing/screening: CVS Amniocentesis Multiple marker screening 1st or 2nd trimester, or combined Ultrasound
Slide 8-

Family Medical History For a family history of a diagnosed genetic condition or birth defect and a patient who is currently pregnant, referral to a Prenatal Diagnosis Clinic is appropriate. Examples: Nephew with Duchenne Muscular Dystrophy Brother with Fragile X syndrome Previous child with spina bifida, etc.
Slide 9-

Family Medical History For a non-specific, but concerning history, referral to a Medical Genetics Clinic (e.g. OHSU) is appropriate. Examples: Close family member with mental retardation, etiology unknown Multiple family members with ‘kidney disease’ Previous child with seizure disorder and developmental delay
Slide 10-

Pregnancy History During pregnancy, any reported exposures or maternal conditions would be reasonable to refer to a genetics service – especially those known to be teratogens E.g. accutane, seizure medications, lithium, coumadin, “street drugs”, high fevers, viral infections, maternal diabetes, etc. Preconception counseling should always include a discussion of folic acid Thought to decrease the risk of neural tube defects by 50-70% 0.4 mg is recommend for all women 4.0 mg is recommended for women at increased risk
Slide 11-

Ethnicity-Based Genetic Carrier Screening Purpose: To detect couples at risk for prenatally diagnosable genetic diseases Tests offered based on ethnic background Should be offered to patients: Seeking preconception counseling, OR Seeking infertility care, OR During the first or early second trimester of pregnancy
Slide 12-

Population Condition Carrier Frequency Carrier Frequencies based on Ethnic Origin
Slide 13-

Principles of Carrier Screening Counseling before screening should include: Purpose, voluntary nature of screening Range of symptoms and severity of each disease Risk of carrier status and affected offspring Meaning of positive and negative results Factors to consider in decision-making Further testing would be necessary for prenatal diagnosis
Slide 14-

Informed Consent Utilize patient resources materials Patient brochures about CF and other ethnicity-based genetic screening available from multiple sources Carrier screening videos can be shown in office settings Document informed consent discussion and patient decision
Slide 15-

Important Points Carrier screening is optional Patient education/informed decision-making is crucial Testing can be done sequentially or concurrently If >12 weeks gestation, discuss concurrent testing Insurance coverage for carrier screening??? Varies by insurer (not covered by OHP and some other major insurers) Genetic counseling is available to carriers and strongly advised for carrier/carrier couples
Slide 16-

Caucasian Patients: ACOG guidelines, Oct. 2001 Offer cystic fibrosis carrier screening to: Individuals with a family history of CF Reproductive partners of carriers/persons with CF Couples where one or both partners are Caucasian & are planning a pregnancy or seeking prenatal care “Make CF screening available” to couples in other racial or ethnic groups at lower risk
Slide 17-

CF Carrier Screening 1/25 to 1/29 carrier rate in general Caucasian population and Ashkenazi Jewish population Carrier screening by DNA mutation analysis ACOG suggests panel of 25 most common mutations Some labs do additional mutations but at higher cost www.genetests.org Mutations differ in severity – contact genetics to discuss particular carrier results
Slide 18-

Carrier Rates: Cystic Fibrosis
Slide 19-

Asian Patients Standard to review MCV If <80, screen for thalassemia w/quantitative hemoglobin electrophoresis Alpha-thalassemia carrier rates up to 1/20 Beta-thalassemia carrier rates 1/30 to 1/50 Cystic fibrosis carrier rate 1/90 or less Detection rate is very low (~ 30%) Not standard to do CF screening Make available upon patient request
Slide 20-

Hispanic/Latino Patients No standard protocol for carrier testing Cystic Fibrosis: carrier rate 1/46 Beta-thalassemia: carrier rate 1/30 to 1/50 Sickle cell or other hemoglobin trait: Carrier rate 1/30 (Caribbean) to 1/200 Could review MCV as a general screen
Slide 21-

African-American Patients Standard to offer Sickle Cell screening Sickle cell carrier rate is 1/10 to 1/12 Use Hb electrophoresis (NOT sickle dex) Standard to review MCV Beta-thalassemia carrier rate about 1/75 If MCV low, offer thalassemia screen w/quantitative Hb electrophoresis CF carrier rate 1/65 no standards re: offering CF carrier screening
Slide 22-

Ashkenazi Jewish Patients Standard of care to offer carrier screening for: Tay-Sachs disease Cystic Fibrosis Canavan disease Familial Dysautonomia All autosomal recessive conditions Carrier testing for other disorders also available (high anxiety/family history?)
Slide 23-

Maternal Serum Screening Tests maternal serum markers to detect increased risk of fetal trisomy 21, trisomy 18 and/or neural tube defects 2nd trimester maternal serum screening 1st trimester maternal serum screening (with or without nuchal translucency measurement) Integrated maternal serum screening Other variations combining 1st and 2nd trimester screening results
Slide 24-

Maternal Serum Screening Patient education points: ‘This is only a screening test’ ‘The test is optional’ ‘A negative result does not guarantee a healthy baby’ ‘A positive result does not mean that the baby has a problem, BUT further testing (ultrasound & CVS or amniocentesis) would be offered’ Offered to all patients regardless of age – ‘there is a small risk in every pregnancy for these conditions’
Slide 25-

2nd Trimester Serum Screening Timing: 15 to 20 weeks gestation Choices: Triple screen Quad screen Cost ~$200 Insurance coverage varies Triple covered by most, Quad by some
Slide 26-

Triple Screen Analytes used (with maternal age): Alpha-fetoprotein (AFP) Unconjugated estriol (uE3) Beta-Human Chorionic Gonadotropin (b-HCG) Detection rates/screen-positive rates vary by lab Detection rates with a 5% screen-positive rate Down syndrome: 60-70% Trisomy 18: 60% NTD: 75-80%
Slide 27-

Quad Screen Analytes used (with maternal age): adds dimeric inhibin-A (DIA) to AFP, uE3 and beta-HCG Detection rates with 5% screen positive rate Down syndrome: 75-80% Trisomy 18: 60% NTD: 75-80% Use quad screen over triple when available and when covered by insurance
Slide 28-

2nd Trimester screening tips Use ultrasound dating if available Even when LMP still used for due date U/S dating gives more accurate results Cons of 2nd trimester screening Later gestation - limits prenatal diagnosis options Not as accurate for multiple gestation Some labs do not offer calculations for twin gestations Pros: Includes screening for NTDs via AFP analysis Often covered by insurance
Slide 29-

1st Trimester Maternal Serum Screening Timing: 24-84 mm CRL (9 to 13+6 weeks gestation) Analytes used (with maternal age): free Beta HCG PAPP-A Detection rates with 5% screen positive rate: Down syndrome: 68% Trisomy 18: 90% Costs: $100-200 for serum $200 plus for NT U/S
Slide 30-

1st Tri Serum + NT Serum results combined with nuchal translucency (NT) measurement * *Measured by an NT-certified ultrasonographer Best visualized at CRL = 45 – 84 mm (11-14 wks gestation) Increased NT = increased risk for Down syndrome / other disorders Detection rates with 5% screen positive rate: Down syndrome – 90%, Trisomy 18 – >90% *ACOG Committee Opinion Obstet Gynecol 2004 Jul;104(1):215-7
Slide 31-

Increased NT Increased NT measurement (>3.5mm) associated with increased risk for: Chromosome abnormalities Major structural cardiac defects NTDs, other structural anomalies, and specific genetic syndromes SAB, IUFA, SGA and stillbirth If normal chromosomes and >NT, can offer: 2nd trimester MSAFP screen Fetal anomaly scan between 18-22 weeks fetal echocardiogram between 20-22 weeks
Slide 32-

Pros: 1st Trimester Serum + NT screen Fingerstick dried blood sample easy to collect and send via prepaid FedEx envelope Draw blood <11 wks if possible (more sensitive) Results take about 1 week Results available at earlier gestation Allows choice of CVS or amnio Higher detection rate than 2nd trimester screen More accurate for multiple gestations Separate ultrasound/NT results on each fetus
Slide 33-

Cons: 1st Trimester Serum + NT screen Requires NT measurement performed at a certified center Often only available at perinatal centers Often necessitates patient travel Does not screen for NTDs Need to discuss 2nd trimester AFP screening with patients who have had 1st trimester screening May not be covered by insurance
Slide 34-

Integrated Serum Testing Combined 1st and 2nd trimester biochemical screening 1st trimester dried blood sample 2nd trimester venipuncture Increased detection rate; decreased false positive rate Combined results given in 2nd trimester after 2nd screen Good for: Communities without NT capabilities and/or CVS Patients who are not highly anxious Patients who cannot afford 1st trimester US/NT screening
Slide 35-

Ultrasound/Sonogram Nuchal translucency (NT) and nasal bone (NB) Accompanies 1st trimester serum screening for Down sy. Performed by NT and NB certified sonographers Fetal anatomy – 18-20 weeks Offered for significant family history of detectable structural defects or genetic syndrome(s), for f/u of positive serum screens, for prenatal history of known teratogens, etc. Fetal echocardiogram - 20-22 weeks Often useful for significant family history of structural cardiac lesions, certain genetic syndromes, certain teratogen exposures, Not perfect - a normal ultrasound does not mean a healthy baby
Slide 36-

Fetal Ultrasound/Sonogram Nuchal translucency (NT) and nasal bone (NB) Accompanies 1st trimester serum screening for Down syndrome. Performed by NT- and NB-certified sonographers Fetal anatomy – 18-20 weeks Offered for significant family history of detectable structural defects or genetic syndrome(s), for f/u of positive serum screens, for prenatal history of known teratogens, etc.
Slide 37-

Fetal Ultrasound/Sonogram Fetal echocardiogram - 20-22 weeks Often useful for significant family history of structural cardiac lesions, certain genetic syndromes, certain teratogen exposures, Patient counseling: Fetal ultrasound is not perfect - a normal ultrasound does not mean a healthy baby
Slide 38-

Ultrasound/Sonogram
Slide 39-

Who to Refer – Ethnic Background Individuals with a family history of cystic fibrosis or other autosomal recessive disease Couples where both members are known carriers for an autosomal recessive disease Couples where one member is a carrier and has additional questions Pregnant carriers who do not have results on the father of baby
Slide 40-

Who To Refer – Positive Family History If patient or partner indicates family history of birth defects, inherited condition(s) or history of pregnancy exposure: Assess level of concern and desire for more information about risks to pregnancy Refer for genetic counseling with patient consent
Slide 41-

Who To Refer – Prenatal Genetic Services Advanced maternal age Request for 1st trimester marker screening with NT Abnormal serum marker screening results Fetal abnormalities on prenatal ultrasound Personal or family history of a known or suspected genetic disorder, birth defect, or chromosome abnormality Family history of mental retardation of unknown etiology Patient with a medical condition known or suspected to affect fetal development
Slide 42-

Who to refer (cont) Exposure to a known or suspected teratogen Either parent or family member with a chromosome rearrangement Parent a known carrier or has a family history of a disorder for which prenatal testing is available Unexplained infertility or multiple pregnancy losses or previous stillbirths Absence of the vas deferens Premature ovarian failure
Slide 43-

Oregon Genetics Providers Portland Oregon Health & Science University Legacy Health Care Northwest Perinatal Services Kaiser-Permanente Eugene Center for Genetics & Maternal Fetal Medicine Bend Genetic Counseling of Central Oregon (cancer only)
Slide 44-

How, When, Where How? Give a center a call When? ASAP Where? Oregon Genetics Clinics Contact List
Slide 45-

Resource Information Provider and patient education materials Family history questionnaire and assessment guide Genetic Web Site Reference List Patient brochures and fact sheets www.genetests.com - list of labs offering carrier testing for specific genetic disorders