# 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.