A MOLECULAR AND GENETIC VIEW OF HUMAN

RENAL AND URINARY TRACT MALFORMATIONS

Adrian S WoolfNephro-Urology Unit

Institute of Child Health, University College London, UK

CLINICAL IMPORTANCE OF KIDNEY MALFORMATIONS

800 children in the UK have end stage renal failure. The commonest causes are: 1. Agenesis (absent kidney)2. Dysplasia (undifferentiated) 3. Hypoplasia (too few nephrons)

LOWER URINARY TRACT MALFORMATIONS

Kidney malformations are often associated with ureter and/or bladder malformations: 1. Vesicoureteric reflux2. Duplicated lower tracts3. Obstructed lower tracts

CAUSES OF KIDNEY AND LOWER URINARY TRACT

MALFORMATIONS1. Mutations of genes expressed during development2. Gross changes of fetal kidney milieue.g. impairment of fetal urine flow3. Subtle change of fetal kidney milieue.g. low protein maternal diet

PRIMARY VESICOURETERIC REFLUX

1. Occurs in 1% babies 2. ‘Reflux nephropathies’ can be congenital or acquired and account for 10% of end-stage renal failure2. Excess risk for vesicoureteric reflux in first degree relatives is x20-503. Some families have dominant inheritance 4. 1p13 locus and other undefined loci

VESICOURETERIC REFLUX

?II:1 II:2

I:2I:1

III:1 III:2 III:3 III:6III:5III:4 III:10III:9III:7 III:8 III:11 III:12 III:13III:15III:14

IV:1 IV:2

Embryonic urinary bladder Adult urinary bladder

Uroplakin Ib Uroplakin III

Vesicoureteric Reflux in the UK Establishing a DNA collection

www.vur.org.uk

DUPLEX KIDNEYS AND LOWER URINARY TRACTS

1. Occur in 1% of individuals2. Occurs with dysplastic kidneys and vesicoureteric reflux3. Excess risk in first degree relatives is about x20-30

FRASER SYNDROME1. Autosomal recessive - fused fingers,membrane across eyes and dysplasticor absent kidneys2. FRAS1 gene is mutated - protein coats the ureteric bud3. Null mutant mouse metanephrosinvolutes with excess apoptosis

Patient Described by George Fraser

Fraser Syndrome vs bl/bl Phenotype

Spectrum of Renal Defects in Fras1 targeted Mutants (b-d)

APOPTOTIC INVOLUTION OF CYSTIC

DYSPLASTIC KIDNEY

RENAL CYSTS AND DIABETES SYNDROME

1. Autosomal dominant or sporadic2. Renal agenesis, cysts, dysplasia, hypoplasia, with diabetes (can require insulin) and uterus malformations3. Hepatocyte Nuclear Factor 1βtranscription factor mutations

Single kidney

Q243fsdelC

Bicornuateuterus

Small kidneys

II

III

IV

Cystic renal dysplasia

1 2

21 3 4 5

1 2

NM NM

NM NM

I1 2

2

DUK507

HNF1β antisense HNF1β sensem

u

ORAL FACIAL DIGITAL SYNDROME TYPE 1

1. Male embryonic lethal – only affected females are born2. X-linked dominant 3. Glomerocystic kidney disease4. OFD1 gene codes for a centrosomal/basal body protein

OFD1Ab Preabsorbed OFD1 Ab

-120Danti ofd1

preabsorbed

EK84 EK75 EK73 EK70 WH

OLE

KID

NEY

v

OFD1 IMMUNOHISTOCHEMISTRY

ub

m

OFD1 PROTEIN IS EXPRESSED IN HUMAN EMBRYONIC KIDNEY MESENCHYME IN VIVO AND IN DERIVED CELL LINES

α-Tubulin mergeOFD1

C

150

100

75

37

25

50

OFD1 PROTEIN - GREENACETYLATED TUBULIN - RED

CAUSES OF KIDNEY AND LOWER URINARY TRACT

MALFORMATIONS1. Mutations of genes expressed during development2. Gross changes of fetal kidney milieue.g. impairment of fetal urine flow3. Subtle change of fetal kidney milieue.g. low protein maternal diet

ANIMAL MODEL OF POSTERIOR URETHRAL VALVESAND FETAL NEPHROPATHY AND UROPATHY

CAUSES OF KIDNEY AND LOWER URINARY TRACT

MALFORMATIONS1. Mutations of genes expressed during development2. Gross changes of fetal kidney milieue.g. impairment of fetal urine flow3. Subtle change of fetal kidney milieue.g. low protein maternal diet

THE EXPERIMENTAL MODEL

Pregnant rats were supplied isocaloricdiets in which the primary variable was the protein content from the day of conception to the end of pregnancy– 18% protein (control)– 9% protein (mild protein restriction)– 6% protein (severe protein restriction)Welham et al Kidney Int 61:1231-1242, 2002

Maternal lowprotein diet

Fewer nephrons

Elevated bloodpressure

Non-renalalterations

Ratembryonic

day 13

Embryonicday 15

Two weekspostnatal

Increasedmetanephric

apoptosis

Decreased cellnumber

Fewer nephronprogenitor cells

Adult

Embryonic kidney

Apoptosis

0

50

100

150

200

250

Series4Series5Series10A

popt

otic

cells

/mm

2P<0.01

P<0.05

Embryonic day 13

18% Protein

9% Protein

6% Protein

Glomerular complement of offspring at 2 weeks of age.

0

5000

10000

15000

20000

6% Protein 9% Protein 18% Protein

Glo

mer

uli * *

Systolic blood pressures of offspring at 4 weeks and 19 weeks of age.

050

100150200

4 weeks 19 weeks

Syst

olic

blo

od p

ress

ure

(mm

Hg)

.18% protein9% protein

* *

REPRESENTATIONAL DIFFERENCE ANALYSIS

• Genes ‘upregulated’ in metanephric kidneys exposed to maternal normal diet:

Cofilin-1, Prox-1, Calmodulin

• Genes ‘upregulated’ in metanephric kidneysexposed to maternal low protein diet:

Cadherin-11

CAUSES OF KIDNEY AND LOWER URINARY TRACT

MALFORMATIONS1. Mutations of genes expressed during development2. Gross changes of fetal kidney milieue.g. impairment of fetal urine flow3. Subtle change of fetal kidney milieue.g. low protein maternal diet

ACKNOWLEDGEMENTS FOR STUDIES OF KIDNEY AND URINARY TRACT MALFORMATIONS

University College London UKMonica Banerjee, Maria Bitner-Glindzicz, Isky Gordon,

Ambrose Gullett, Peter Cuckow, Chris Fry, Maggie Godley, Monika Hermanns, Mike Hubank, Maria Kolatsi-Joannou, Dagan Jenkins, Liam McCarthy,

Sue Malcolm, Peter Nyirady, Donald Peebles, Karen Price, Paul Riley, Leila Romio, Peter Scambler, Naima Smeulders, Niki Thiruchelvam,

Simon Welham, Melissa Whitten, Duncan Wilcox, Paul Winyard, Su-Ping YangElsewhere in UK

Coralie Bingham, Sally Feather, Andrew Fry, Judith Goodship, Tim Goodship, Andrew Hattersley, Albert Ong, Jenny Southgate, British Association for Paediatric Nephrology

Elsewhere in the worldTIGM Naples Italy - Brunella Franco and colleagues

NYU New York USA – Tung-Tien Sun and colleagues