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Paediatric Renal Genetic Clinics

Paediatric Renal Genetic Clinics. Adrian S. Woolf University of Manchester. Children ’ s Hospital and University of Manchester, UK. The Nobel Prize in Physics 2010 Andre Geim and Konstantin Novoselov University of Manchester, UK. Discovered graphene… a new class of material…

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Paediatric Renal Genetic Clinics

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  1. Paediatric Renal Genetic Clinics Adrian S. Woolf University of Manchester

  2. Children’s Hospital and University of Manchester, UK

  3. The Nobel Prize in Physics 2010Andre Geim and Konstantin NovoselovUniversity of Manchester, UK Discovered graphene… a new class of material… ….2D atomic crystals

  4. Clinical Importance of Malformations of the Human Kidney and Urinary Tract ● CHILDREN: Of the 800 children in the UK with renal failure severe enough to need treatment with dialysis and kidney transplantation, 40% have renal malformations. ● ADULTS: Several thousands of UK adults who have severe renal failure were born with abnormal kidneys. ● FETUSES: Renal tract malformations are among the commonest anomalies detected upon fetal screening in mid-gestation.

  5. CLINICAL IMPORTANCE OF KIDNEY MALFORMATIONS Three main histological varieties of kidney malformations: Hypoplasia (too few nephrons) Dysplasia (undifferentiated kidney sometimes with cysts) Agenesis (absent kidney)

  6. Spectrum of Human Kidney Malformations Worsening excretory function → →

  7. The Beginning of the Kidney: Ureteric Bud (UB) Penetrates Renal Mesenchyme (RM) RM UB Pitera JE et al Hum Mol Genet 17:3953-3964,2008

  8. Back in 1991, Genetics of Human Kidney Development Seemed Rather Simple….

  9. TWO PAEDIATRIC RENAL GENETICS CLINICS Between 2006 and 2009, I ran a clinic at Great Ormond Street Hospital, London with a focus on ‘Genetics of Renal Tract Malformations' … A clinical genetics expert, Prof Raoul Hennekam sat in with me and advised me. Since moving to Manchester in 2010, I have run a similar clinic with Dr Bronwyn Kerr

  10. RENAL TRACT MALFORMATION/GENETICS CLINIC • The idea was see whether we can help with genetic diagnosis and/or counselling in families with either: • a child with a renal tract malformation and another organ involved, developmental delay, external dysmorphic features etc) or • a child with a renal tract malformation and one or more siblings or a parent with a renal tract malformation

  11. CLINICAL REASONS TO MAKE GENETIC DIAGNOSES OF RENAL TRACT MALFORMATIONS ● Finding mutations of developmental genes provides families with reasons why disease occurred. ● Genetic diagnosis may suggest useful future health screens and also external factors which can be modified to enhance health. ● Better classification will optimise clinical follow-up and allow better outcome studies.

  12. SUMMARY OF CLINIC 2006-2009 ● Established as a clinical service rather than a research clinic. ● A few relevant gene tests (especially HNF1B) available on UK Genetic Testing Network and comparative genomic hybridization by microarray available at GOSH from 2008. ● 91 referrals (most from Paediatric Nephrologists and Urologists), from 68 families. ● 27 children could be assigned to a recognised genetic syndrome and/or were found to have a mutation considered to be the cause of the renal malformation.

  13. MULTICYSTIC DYSPLASTIC KIDNEY (MCDK) Unilateral MCDK Cysts → Atretic ureter → Contralateral kidney Often large (‘hypertrophy’) Normal urinary bladder

  14. FAMILY ONE • JP – female now a teenager. • Antenatal diagnosis of right multicystic dysplastic kidney: this involuted (spontaneously disappeared) after birth. • Left solitary functioning kidney was ‘normal size’ (should be larger than normal) and was echobright on ultrasound scan. • Between 9 and 12 years old, increasing weight centiles with normal fasting glucose and but raised insulin levels. • Developed overt diabetes mellitus (non ketotoic) with blood sugar of 30 mM.

  15. MULTICYSTIC DYSPLASTIC KIDNEY - RADIOLOGY Ultrasound scan 32 weeks gestation Postnatal renal isotope scan ↑ ↑ Shukunami K et al J Obstet Gynaecol 24:458-459, 2004 ‘Normal’ MCDK kidney (no uptake)

  16. INVOLUTION OF MULTICYSTIC DYSPLASTIC KIDNEYS Neonatal ultrasound………..and two years later ● These massive structures usually ‘involute’ over weeks/months, prenatally or postnatally, often becoming undetectable by US

  17. FAMILY ONE ● She has a heterozygous mutation of the hepatocyte nuclear factor 1B (HNF1B) transcription factor gene ● Predicted to result in aberrant splicing ● Parents have normal kidney US scans ●Mother has normal HNF1B; father not yet tested.

  18. RENAL CYSTS AND DIABETES SYNDROME (RCAD) ● RCAD is a relatively newly-recognised syndrome which was defined at the start of the 2000’s ● Autosomal dominant or sporadic ● Diabetes mellitus (MODY5) and uterus malformations ● Renal disease resulting from abnormal development (but not classic ‘diabetic nephropathy’) ● Renal cysts (histology showing cystic dysplasia and/or glomerulocystic type of polycystic kidney disease) ● Hepatocyte Nuclear Factor 1Btranscription factor mutations (chromosome 17cen-q21.3)

  19. HNF1BGENE EXPRESSED IN HUMAN EMBRYONIC KIDNEY Kolatsi-Joannou M et al,J Am Soc Nephrol 12:2175-2180, 2001

  20. HNF1B MUTATIONS CAN BE ASSOCIATED WITH DIABETES MELLITUS AND PANCREAS HYPOPLASIA Normal Individual HNF1B mutation Body of pancreas Head of pancreas Haldorsen IS et al Diabet Med 25:782-787, 2008

  21. HNF1BMUTATIONS • Great Ormond Street Nephrology Unit • Since we started looking in 2001, up to 2007 we found 21 families with mutations of HNF1B • Renal phenotypes are rather varied and include MCDK, solitary functioning kidney, cystic dysplastic kidneys, pelviureteric junction obstruction and the glomerulocystic variety of polycystic kidneys

  22. HNF1B Mutations not only Cause Renal Malformations but also Lead to Abnormal Kidney Physiology after Birth ● Blood magnesium levels in children with renal malformations ● Those with HNF1B mutations can have low blood magnesium levels ● HNF1B transactivates FXYD2, a gene implicated in magnesium handling in the distal convoluted tubule Adalat S et al J Am Soc Nephrol 20:1123-1131, 2009

  23. FAMILY TWO • CK – male 5 years old • Presented with icthyosis and undescended testicles • Found to have a hypoplastic left kidney and normal sized right kidney • Two of his mother’s brothers also had icthyosis • One of them had a solitary functioning kidney and went into end-stage renal failure

  24. FAMILY TWO • Index case and his two uncles have X-linked Kallmann syndrome. Recessive condition, so female carriers are well • The gene is expressed in the ureteric bud and collecting ducts, and also in the front of the brain • Patients have anosmia, hypogonadotrophic hypogonadism and often have unilateral renal agenesis • In the index case, the icthyosis is caused by a continguous gene deletion of the Steroid Sulphatase gene

  25. EXPRESSION OF ANOSMIN-1 Glomerular basement membrane Ureteric bud epithelia Hardelin JP et al Dev Dyn 215:26-44, 1999

  26. FAMILY THREE • LS – one year old • Normal antenatal renal scan • Respiratory distress • Found to have raised creatinine and bilateral hypoplastic kidneys • Visual impairment with abnormal visual evoked potentials

  27. Dutton GN Eye 18:1038-1048, 2004

  28. OPTIC NERVE COLBOMA Dutton GN Eye 18:1038-1048, 2004

  29. FAMILY THREE • Index case has heterozgous mutation of the Paired Box 2 (PAX2) gene • Renal coloboma syndrome • Commonest renal lesions are hypoplasia; VUR and MCDK also reported • Father of the index case has ‘slightly anomalous optic disc up’

  30. BREAKTHROUGH IN 1995 Sanyanusin P et alNature Genetics 9:358-364, 1995

  31. RENAL COLOBOMA SYNDROME ● Autosomal dominant inheritance ●Highly variable presentation even in the same family ●Optic nerve colobomas ●Kidney hypoplasia or dysplasia ● ? Secondary glomerular lesions ●Ureter malformations Sanyanusin P et alNature Genetics 9:358-364, 1995 Eccles MR and Schimmenti LA Clin Genet 56:1-9, 1999

  32. PAX2 TRANSCRIPTION FACTOR PAX2 is expressed in the developing eye and renal tract. It prevents death of undifferentiated cells Human fetal ureter Human fetal kidney Winyard PJ et alJ Clin Invest 98:451-459, 1996

  33. FAMILY FOUR • ES – female 2 years old • Presented with ‘hidden eyes’ (cyryptophthalmos), laryngeal web, fused fingers and toes, abnormal genitalia and malformed hindgut. • Has a solitary, pelvic kidney • Previous sibling – terminated and had bilateral renal agnenesis

  34. FRASER SYNDROME ● Autosomal recessive ● Slavotinek and Tifft (J Med Genet 2005) reviewed 117 cases…….. Major criteria: cryptophthalmos, syndactyly, abnormal genitalia, and a sibling with Fraser syndrome

  35. RENAL FEATURES OF FRASER SYNDROME ● Slavotinek and Tifft (J Med Genet 2005) review of 117 cases……. 27% had ‘bilateral renal agenesis’ 19% had ‘unilateral renal agenesis’ 14% had renal ‘cystic dysplasia’ 14% had renal ‘hypoplasia’ 20% had absent or small urinary bladder

  36. FRAS1 PROTEIN AND HOMOZYOUS MUTATIONS Human Blebbed mouse FRAS1 codes for a 4007 amino acid protein (MacGregor L et al Nature Genet 34:203-208, 2003)

  37. IN FRASER SYNDROME THE URETERIC BUD (UB) FAILS TO PENETRATE RENAL MESENCHYME (RM) RM UB Pitera JE et al Hum Mol Genet 17:3953-3964,2008

  38. FAMILY FIVE • AF – female index case now seven years old • Potter sequence (oligohydramnios and bilateral renal malformation) in two previous siblings. • Oligohydramnios at 33 weeks gestation. • Subsequently she had a diagnosis of bilateral renal hypoplasia/dysplasia • Aged 3 years, her renal function was about 1/5th of normal.

  39. THREE GENERATIONS AFFECTED BY KIDNEY HYPOPLASIA AND DYSPLASIA Kerecuk L et al Nephrol Dial Transplant 22:259-263, 2007

  40. THREE GENERATIONS AFFECTED BY KIDNEY MALFORMATIONS:MIS-CLASSIFICATION OF TWO ADULTS “Focal segmental glomerulosclerosis” ► ◄ “Minimal change nephrotic syndrome” ► ◄ Kerecuk L et al Nephrol Dial Transplant 22:259-263, 2007

  41. FAMILY FIVE • Looks like an autosomal dominant disorder • Very variable expression of kidney disease with fetal, childhood and adult presentations • No syndromic clinical features • Normal analyses of PAX2, HNF1band EYA1 genes • ? A new renal malformation gene ?

  42. FINAL THOUGHTS AND QUESTIONS • Genetic testing may cost several hundred Euros but…… • Finding a mutation provides a family with an answer to their often long-sought question “why was my child born with a kidney malformation?” but….. • Should we perform genetic and/or renal ultrasound screening of parents, siblings and the ‘next generation’. • Nephrologists need to link-up with clinical geneticists for help with counselling • Why can the severity of renal malformation vary considerably within one family? (‘modifying’ genes)

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