Mutations in the protocadherin 19 gene cause epilepsy in females by a mechanism called cellular interference - Illumina
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Mutations in the
protocadherin 19 gene
cause epilepsy in females
by a mechanism called
cellular interference
Christel Depienne
UF de neurogénétique & CRicm
Hôpital de la Pitié-Salpêtrière, Paris
Clinical Implications of Arrays & Next Generation Sequencing Technologies
Seminar, Paris, 10/05/2010
Severe myoclonic epilepsy of infancy
or Dravet syndrome
Normal PMD & MRI before the onset of seizures
Onset < 1 yr: seizures +++ triggered by fever
Febrile and afebrile polymorphic seizures
(generalized, partial seizures & absences)
Pharmacoresistant
Psychomotor delay, myoclonic jerks > 2 yrs Na+
Mental retardation, behavioral disturbances
β1 β2
Sporadic cases
α1
70-80% de novo mutations in the SCN1A gene P
P P
(voltage-gated sodium channel alpha 1 or Nav1.1)
Search for new genes responsible for Dravet
syndrome
> 121 SCN1A-negative
patients
Search for micro- Illumina 370K
rearrangements arrays
Identification of a male patient with a hemizygous
Xq22.1 deletion
Mother
Patient 1
98.7 98.9 99.1 99.3 99.5
pseudogene pseudogene pseudogene PCDH19
Function of protocadherins in the CNS • Highly expressed in CNS • Cadherin superfamily (δ2 protocadherin) • Membrane protein (6 extracellular EC domains, 2 intracellular CM domains) • Ca+-dependent homophilic/ Gaitan et Bouchard, 2006 heterophilic Interactions • Potential role in neuronal survival & migration during development Screening of PCDH19 in 73 SCN1A-negative DS patients
Identification of 9 different point mutations in
11 unrelated female patients
c.142G>T/ c.352G>T/ c.859G>T/ c.506del/ c.1036_1040dup/
p.Glu48X p.Glu118X p.Glu287X p.Thr169SerfsX43 p.Asn347LysfsX23
A R E/X T K V E/X I T R E/X L L T/S P/P N/T I N/K L/S L/T
Proband
Control
c.361G>A/ c.595 G>C/ c.1019A>G/ c.1628T>C/
p.Asp121Asn p.Glu199Gln p.Asn340Ser p.Leu543Pro
I K D/N L D R E/Q T D T N/S D P S L/P Q
Proband
Control
Pedigrees & segregation of the mutations in the
families
Family 1 Family 2 Family 3 Family 4 Family 5 Family 6
del = whole gene m = p.Glu287X m = c.1036_1040dup5
m = p.Glu48X m = p.Glu118X m = p.Glu287X
deletion v = p.Arg1107Gly
+ +/+ m +/+ + +/+ + +/+ m
v +/+
2 m
+/+ m +/+
+/+ del m/+ m/+ +/+ +/+ m/+ +/+ m
m/+
v/+ m/+ m/+
m/+
Family 7 Family 8 Family 9 Family 10 Family 11 Family 12
m = c.506delC m = p.Asp121Asn m = p.Glu199Gln m = p.Asn340Ser m = p.Asn340Ser m = p.Leu543Pro
+ +/+ m +/+ +/+ + +/+ + +/+ m +/+
+
m/+ m/+ m/+ m/+ m/+
m/+
An unusual X-linked inheritance
Recessive X-linked X-linked with male sparing
..
.
. .
.
PCDH19
Affected Unaffected Unaffected AffectedPrinciple of cellular interference
Normal individuals Mutated males Mutated heterozygous
(male/ female) (hemizygous) females
Random X inactivation
Mosaïc mutated males
WT protocadherin 19 Mutated protocadherin Co-existence of
is expressed in all 19 is expressed in all neurons expressing
neurons neurons WT and mutated
protocadherin
Asymptomatic Asymptomatic Epilepsy and MRMosaïcism in the patient with the PCDH19 deletion
Lymphocytes Fibroblasts
A 100% B 47% 53%
Patient
(male)
C D
Control
(female)Micro-rearrangements of PCDH19 in females
Deletion of exons 1-3 Whole gene deletions N07 1329 (family 18)
6.3 Mb
+ +/+ + +/+
del/+ +/+ del/+ del/+ N07 0897 (family 17)
0.5 Mb
1,20
Exon1
1,00 Exon2
Exon3
0,80 Exon4
0,60
Exon5 N08 0125 (family 16)
65 Kb
Exon6
0,40
0,20
0,00
N 08 0125 N 07 0897 N 07 1329 WT1 WT2
TSPAN6
PCDH11X NAP1L3 DIAPH2 PCDH19 SRPX2
FAM133A SYTL4
TNMDMutations of PCDH19 in female patients with
epilepsy but without cognitive impairment
Generalized epilepsy with febrile seizures Cryptogenic partial epilepsy
m/+ m +/+
m/+ m/+ m/+ m/+ m/+
m/+
c.2656 C>T / p.Arg886X c.437 C>G / p.Thr146Arg
Exon 4 Exon 1
V N S R/X A H S P G T/R R I
Patient Patient
Control ControlConclusions • High-density SNP arrays are a good tool to identify micro- rearrangements and new genes • PCDH19: new gene responsible for epilepsy +/- mental delay • Frequent mutations: 15% of female patients with epilepsy and FS • Unusual X-linked inheritance affecting mainly females • Familial / sporadic cases (inherited / de novo) • New pathophysiological mechanism : cellular interference
Cliniciens
Alexandra Afenjar, Paris
U975 Alexis Arzimanoglou, Lyon
Delphine Bouteiller Nadia Bahi-Buisson, Paris
Alexis Brice Patrick Berquin, Amiens
Eric Leguern Marie Bru, Nantes
CRICM Claude Cances, Toulouse
Denys Chaigne, Strasbourg
UF neurogénétique Emmanuel Cheuret, Toulouse
moléculaire et cellulaire Cytogénétique Anne Dusser, Kremlin-Bicêtre
Oriane Trouillard Boris Keren Agnès Gautier, Nantes
Eric Leguern Baya Benyahia Brigitte Gilbert-Dussardier, Poitiers
Isabelle Gourfinkel-An, Paris
Delphine Héron, Paris
P3S Annie Lannuzel, Paris
Wassila Carpentier Gaetan Lesca, Lyon
Florent Soubrier Hélène Maurey, Kremlin-Bicêtre
Sophie Meyer, Bordeaux
Rima Nabbout, Paris
Institut Cochin Isabelle Py, Cholet
Karine Poirier Serge Rivera, Bayonne
Jamel Chelly François Rivier, Montpellier
Agathe Roubertie, Montpellier
Thanks to the families! Dominique Steschenko, Nancy
Sandra Whalen, Paris
Financements: GIS Maladies rares, AP-HP, INSERM Et les autres...Craniofrontonasal syndrome
• Another disease with unusual X-linked inheritance
Forward
signaling
Wieland et al, 2004
Twigg et al, 2004 Eph R
Ephrin
Mutations in Ephrin B1 (EFNB1 en Xq12)
• Mouse model supporting cellular
Reverse
interference as the pathological mechanism signaling
Compagni et al, 2003 D’après Wieacker & Wieland, 2008You can also read
