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]