Handbook of Genetic Counseling/Abnormal Triple Screen and Family History of PKD

Abnormal Triple Screen and Family History of PKD Introduction What have you been told about why you are here today? We want to discuss the triple screen results and what they really mean We want to get a family history to assess for any other risks related to pregnancy We want to talk about the different testing options available to you. Family history update (at beginning depending on level of anxiety) Who in the family has been diagnosed with PKD? What age were they diagnosed? Do any of your family members have high blood pressure? Do any other people in your family have kidney problems? Medical History (related to PKD) Do you see a doctor regularly? Are you currently on any medication? Have you had a renal ultrasound or CT scan? Have you experienced any urinary tract infections? Have you had high blood pressure? Have you experienced any pain in your stomach or back? Pregnancy History Verify dates Any exposures? Any cig/alcohol/drug use? Any increase in blood pressure? Any ultrasounds so far? When is the next one scheduled? Triple screen info. The test itself Best results at 16-18 weeks gestation (can be done from 15-22 weeks) Tests mother's blood NOT diagnostic...simply an indication for additional testing Uses three markers to determine indicators for certain fetal problems The three markers produced by the fetus and the placenta Alpha feto protein(AFP) Human chorionic gonadotrophin (HcG) Most sensitive risk factor for DS Greater than 2.5 MOM indicated risk for DS Estriol Median of 0.5 MOM in Trisomy 18 Serum markers results AFP >2.5 MoM indicates a normal AFTN AFP <0.75 MoM indicates a Trisomy 21 hCG >2.5 MoM indicates a Trisomy 21 hCG <0.55 MoM indicates a Trisomy 18 E3 <0.8 MoM indicates a Trisomy 18 or 21 Patient's results AFP =1.oo , HcG=2.21 , UE3=0.99 Increased risk for Down syndrome Explain chromosomes and what Down syndrome is Trisomy 21 (usually - every cell of body) Characteristics mental retardation (mild to moderate) heart difficulties ear infections Do everything a regular kid can…ride a bike, walk, talk Slower to reach milestones Facial features There is no cure Calculating risk for Down Syndrome (explain how they determine num.) Look at maternal age + AFP MoM + hCG MoM + uE3 MoM = Down Syndrome Risk Risk ³ 1/270 is considered screen positive This is equal to the midtrimester DSR for 35 year-old women AMA woman's risk may be made less by the triple screen results, but it is still considered a test positive because of her age. Recommendations for abnormal tests Ultrasound for examination of physical abnormalities Down Syndrome Nuchal fold (2nd trimester) detects 34% Nuchal translucency (1st trimester) detects 77% Short femur/humerus (detects 80-90% when combined with one of the following two) Echogenic bowel Short ear Amniocentesis Explain procedure 1/200 risk for complications Can't detect all problems with the baby BUT will determine chromosome status Fetal karyotype Down Syndrome Triploidy Trisomies 13, 18 Other chromosomal abnormalities The Basics of PKD Definition (Polycystic Kidney Disease) Multiple cysts in the kidney leading to kidney dysfunction Prevalence = 1/400 - 1/1000 Characteristics 90% penetrant initial signs = high blood pressure, blood in urine (50%), pain in side, back or abdomen, UTI, kidney stones (20-30%) Final stage = renal failure (60%) after age 40 Mitral valve prolapse (26% compared to gen pop 2-3%) aneurysms (5-10%) - occurs in familial clusters liver cysts are possible Diagnosis/medical management renal ultrasounds only after age 30 is a negative ultrasound = 5% risk of disease computed tomography (CT) - to detect aneurysm MRI Prevention Diet control = avoid red meat, eat low protein diet, less salt, fresh fruits and veggies, drink lots of water, avoid caffeine Treatment For pain acetaminophren may help laparoscopic surgery to "unroof" cysts For renal failure dialysis renal transplant (75-80% of kidneys work for 5 years) Inheritance (dominant more commonly - recessive is RARE) Description of autosomal dominant and why this is the type Chance of recurrence if the mother has it = 50% chance Chance of recurrence if the mother doesn't have it same as population risk= <1%???? approximately 10% of the PKD patient community became infected through spontaneous mutation, and not through inheritance. Genetics Two genes identified (a third suspected) PKD1 - 16p (90% of PKD) DX is earlier, progresses more rapidly, more likely to be hypertensive PKD2 - chromosome 4 Testing is done through linkage Her options A amniocentesis for chromosome risk A renal ultrasound for herself (PKD surveillance) If it is negative and she is 30+, chance of having PKD is <5% Testing by linkage analysis for herself and family Costs approx. $2200 per family >95% accurate in families Prenatal determination (preferably after linkage has been established) CVS testing for linkage studies (9-15 weeks) Amniocentesis for linkage studies (15+ weeks) Psychosocial issues How her brothers illness has affected her Scared about the possibility of having PKD? Worried about PKD for baby? Would a diagnosis of PKD influence a pregnancy decision? How would having a child with DS feel? Support and resources at home? Would the dx of DS influence pregnancy planning? Resources for patient [Polycystic kidney disease access center http://www.nhpress.com/pkd/] [www.adam.com http://www.adam.com] Notes The information in this outline has not been updated since 2003.