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Genetic counseling: Polycystic Kidney Disease

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Polycystic Kidney Disease

IntroductionEdit

  • Greet the family/parent
  • What do you understand about why you are here in genetics today?
  • What questions or concerns do you want to have addressed today?

Elicit Medical HistoryEdit

(interim history form)

  • update medical history since last seen
  • determine if there have been any problems since released from the hospital
  • assess developmental history

Update Family HistoryEdit

  • Update pedigree
  • determine if there are any other family members with kidney problems, heart problems, liver problems or that died in early infancy

What is Polycystic Kidney Disease (PKD)?Edit

  • Two main types
    • Autosomal Dominant PKD (adult PKD)
    • Autosomal Recessive PKD (infantile PKD)

ADPKDEdit

  • Etiology and Natural History
    • gene PKD1 mutated in about 85% of cases
    • gene PKD2 mutated in about 15% of cases

symptoms usually develop beginning in early adulthood although can be found in the infant period or not begin until later in adulthood

    • large amount of variability both within and between families
  • Prevelance and Inheritance
    • most common single gene disorder that is potentially lethal
    • prevalence at birth: 1/400 - 1/1000
    • 10% of cases due to new mutation
    • occurs in all races
    • inherited in autosomal dominant fashion
      • if one parent is affected there is a 50% chance of having an affected child
  • Symptoms
    • multiple bilateral renal cysts (100% of cases)
      • leads to end stage renal insufficiency by 60 years old in 50% of cases
    • cysts in other organs specifically the liver (20% by 3rd decade; 75% by 6th decade)
    • intracranial aneurysms (10% of cases)
      • more common in patients with family history of intracranial aneurysms (22%) than those without this history (6%)
    • mitral valve prolapse and other heart defects
  • Diagnosis
    • patients with known 50% risk
      • at least 2 cysts either unilateral or bilateral by 30years of age
      • large kidneys without cysts in infants and children
    • patients with no known risk
      • bilateral renal enlargements and cysts
      • in absence of indication for different renal cystic disease
      • suggestive of ADPKD, but not definite diagnosis
    • Differential from:
      • ARPKD - unaffected parents
      • Glomerulocystic kidney disease - minimal tubular involvement
  • Molecular Testing
    • Linkage analysis - need a large number of family members to establish which gene is responsible
    • Prenatal Testing - only available after a mutation has been identified in an affected family member
  • Management
    • no treatment for disease itself
    • treat symptoms to prevent premature death and alleviate pain

ARPKDEdit

  • Etiology and Natural History
    • mutation in PKHD1 locus (6p21) present in all studied patients with ARPKD
    • enlarged echogenic kidneys found in perinatal period
    • large amount of variability both within and between families
    • 30% of patients with ARPKD die in neonatal period
  • Prevelance and Inheritance
    • prevalence: 1/20,000 - 1/40,000
    • prevelance may be underestimated due to death in neonatal period
    • carrier frequency: 1/70
    • inherited in autosomal recessive fashion
      • if both parents are carriers there is a 25% chance of having a child who is affected , 50% chance of having a child who is a carrier, and a 25% chance of having
  • Symptoms
    • enlarged, echogenic kidneys with poor differentiation (100% of cases)
      • renal function impaired in 70-80% of cases
    • hypertension
      • usually occurs within first week of life
    • Liver disease (45% of cases at presentation)
    • pulmonary hypoplasia resulting from oligohydramnios
    • other abnormalities: low set ears, micrognathia, flattended nose, growth deficiency
  • Diagnosis
    • enlarged echogenic kidneys with poor differentiation
    • one or more of the following:
      • absence of renal cysts in parents
      • signs of hepatic fibrosis
      • pathoanatomical proof of ARPKD in affected sibling
      • parental consanguinity suggesting AR inheritance
    • Differential from:
      • ADPKD - more likely to have bilateral macrocysts
      • Glomerulocystic kidney disease - minimal tubular involvement
  • Molecular Testing
    • Linkage analysis - based on accurate diagnosis of ARPKD in affected individual and accurate understanding of relationships in family
    • Prenatal Testing - only available after a linkage has been identified in an affected family member
  • Management
    • no treatment for disease itself
    • treat symptoms to prevent premature death and alleviate pain
      • stabilize respiratory function
    • feeding difficulty and growth failure in chidren

Psychosocial IssuesEdit

  • uncertainty of diagnosis and prognosis may lead to anxiety
  • possibity that parent could find out they have the diease (for ADPKD)
  • guilt over passing trait to child
  • Concern for risks to future pregnancies
  • Are you interested in pursuing linkage analysis?
  • How are you dealing with your son's health problems?
  • Are you anxious about the possibility of upcoming surgeries?
  • Reassure that this could not have been prevented

Recommended Follow-up for PKDEdit

  • renal ultrasounds to monitor cysts and function
  • control of hypertension
  • CT scan to detect aneurysm (ADPKD)
  • monitor liver function

ResourcesEdit

  • PKD foundation (www.pkdcure.com)

ReferencesEdit

  • Practical Genetic Counseling
  • OMIM
  • GeneClinics
  • GeneTests
  • Human Congenital Malformations

NotesEdit

The information in this outline was last updated in 2002.



This material has been imported fom the wikibook "Genetic counseling"[ http://en.wikibooks.org/wiki/Genetic_counseling] under the GNU Free Documentation License.

Heckert GNU white Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled "GNU Free Documentation License."

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