1. Strutturazione della
consulenza genetica
nella SLA familiare e sporadica
Marcella Zollino
Istituto di Genetica Medica
Università Cattolica Sacro Cuore
Policlinico A. Gemelli, Roma
Lecce, 20 gennaio 2015
15. Ereditarietà autosomico-recessiva (AR)
4) Rischio riproduttivo per genitori eterozigoti:
25 % figli affetti
25 % figli omozigoti sani
50 % figli eterozigoti per la mutazione
Rischio di ricorrenza in ogni futura gravidanza: 25%
16. Ereditarietà autosomico-recessiva (AR)
5) Consanguineità nei genitori
mutazioni rare
stesso allele in omozigosi
N.B. Quanto più frequente è lo stato di portatore eterozigote,
meno influente è la consanguineità nei genitori
18. La maggior parte delle mutazioni presenti sul cromosoma X sono recessive e
quindi si manifestano solo nei maschi (per la loro condizione di emizigoti)
-La presenza della malattia dipende dal sesso (sono malati solo i maschi)
-La malattia non si trasmette mai da maschio malato a figlio ma da maschio
malato a circa la metà dei nipoti maschi, attraverso femmine sane (che sono
portatici).
19. Malattie a trasmissione X-linked. Rischi riproduttivi relativi a:
A) femmina eterozigote e maschio emizigote normale
20. 2) Assenza di trasmissione da maschio malato
a figlio maschio malato
3) Maschio malato: 100% di figlie femmine portatrici
23. Sclerosi Laterale Amiotrofica
(SLA)
Definizione SLA familiare (FALS) e SLA sporadica (SALS)
Le FALS sono tutte mendeliane?
Ipotesi multigenica delle SALS e FALS: fatti e prospettive
24. Sclerosi Laterale Amiotrofica
(SLA)
Definizione SLA familiare (FALS) e SLA sporadica (SALS)
Le FALS sono tutte mendeliane?
Consulenza genetica nelle FALS e nelle SALS con mutazione
Ipotesi multigenica delle SALS e FALS fatti e prospettive
25. Sclerosi Laterale Amiotrofica
(SLA)
Definizione SLA familiare (FALS) e SLA sporadica (SALS)
Tempo per esame genetico sistematico nelle SALS?
Le FALS sono tutte mendeliane?
Consulenza genetica nelle FALS e nelle SALS con mutazione
Ipotesi multigenica delle SALS e FALS fatti e prospettive
29. In tutti i pazienti con sospetta SLA, atrofia muscolare progressiva,
sclerosis laterale primaria o demenza fronto-temporale, bisogna
raccogliere una dettagliata storia familiare
genitori
fratelli
nonni,
cugini
zii
43. FALS
SALS
SLA sporadiche e familiari sono clinicamente indistinguibili
Inclusioni TDP-43-positive sono presenti in entrambi
Tutti i geni trovati nelle SLA familiari son stati identificati anche nelle
forme sporadiche
48. Spiegazioni Possibili
• La diagnosi di SLA sporadica è erronea;
sono in realtà familiari
– Non ci sono conoscenze sui familiari
– Familiari hanno avuto la SLA ma non è stata
diagnosticata
– Familiari deceduti per altre malattie prima di
sviluppare la SLA
• Le famiglie sono piccole
49. Studi genetici in 8 famiglie
Spiegazioni possibili:
le mutazioni sono de novo
53. • SOD1: p.E133del, p.L67P, p.D11Y, p.D90A
• TARDBP: p.G294V
• C9ORF72: 2 pazienti
Possibili spiegazioni
Bassa penetranza
La mutazione dei casi sporadici era presente in
familiari asintomatici in 7/8 famiglie:
54. 92 y
*
onset 55 y
E133del
*
L67P
SOD1
76 y
onset 36 y
C9orf72
78 y
*
onset 47 y
56. penetranza
• Concetto generico difficilmente applicabile a
singoli pedigrees nel setting clinico
• Paradigma SOD1: 170 mutazioni molte delle
quali identificate in una o due famiglie.
Penetranza (patogenicità?) difficilmente
definibile(eccezioni A4V)
• C9ORF72: è la mutazione più frequente nelle
SLA sporadiche
57.
58. 37.6% (95% CI 33.7-41.69)
5.8% (95% CI 4.4-7.4)
6.3% (95% CI 5.6-7.1)
25.1% (95% CI 20.9-29.6)
61. 64 y
38 y
p.I46V ANGC9ORF72 expansion
70 y
C9ORF72 expansion
+
p.I46V ANG
**
62. Mutazioni multiple
• 1 paziente: C9ORF72+ANG
• 1 paziente: SOD1+ANG
La frequenza di mutazioni doppie osservate in pazienti (0.4) era
circa 7 volte maggiore di quella attesa per caso (0.05)
76. • Clinical DNA analysis for gene mutations should only be performed in cases with a
known family history of ALS, and in sporadic ALS cases with the characteristic
phenotype of the recessive D90A mutation (GCPP).
• Clinical DNA analysis for gene mutations should not be performed in cases with
sporadic ALS with a typical classical ALS phenotype
• In familial or sporadic cases where the diagnosis is uncertain, SMN, androgen
receptor or TARDBP, FUS, ANG or SOD1 DNA analysis may accelerate the
diagnostic process
• Before blood is drawn for DNA analysis, the patient should receive genetic
counselling. Give the patient time for consideration. DNA analysis should be
performed only with the patients informed consent (GCPP).
77. Presymptomatic genetic testing should only be per- formed in first-degree adult blood
relatives of patients with a known gene mutation. Testing should only be performed
on a strictly voluntary basis as outlined and should follow accepted ethical principles
.
. Results of DNA analysis performed on patients and their relatives as part of a
research project should not be used in clinical practice or disclosed to una ectedff
rela- tives.Theresearchresultsshouldbekeptinaseparatefile and not in the patients
standard medical chart (GCPP).
78.
79.
80. FALS
225 index
SALS
725
mean age of onset 55 years 56 years
Median age of onset 55 y (range 21- 85) 58 y (range 21-87)
M/F 1.4 1.4
median disease duration 33 m (range 3-336) 48 m (range 1-354)
FALS SALS
553
mean age of onset 55. 8 years (53 index)
54.3 years (110 index+r)
60.25 years
Cattolica. Roma
81. • British Twin Study: 10.872 certificati di morte di pz
con SLA - identificate 75 coppie di gemelli di cui
almeno uno con SLA
• Swedish Twin Register: su 86.411 coppie di
gemelli identificati 73 coppie di gemelli, di cui
almeno uno con SLA
• Ereditabilità : 0,61 (0,38-0,78)
• Componente ambientale: 0,39 (0,22-0,62)
82.
83.
84. A gene disease with a penetrance of:
0.9 will seem sporadic in one-third of cases
0.5 will seem sporadic in two-thirds of cases
86. Double mutations
• 1 patient: C9ORF72+ANG
• 1 patient: SOD1+ANG
the frequency of double mutation found in patients (0.4) was
approximately 7 times greater than would be expected by
chance (0.05)
90. Stdio di 8 famiglie di SLA sporadiche
Spiegazioni possibili
La mutazione è de novo
91.
92. • 172 mutazioni (ALSoD): missenso, non
senso, delezioni
• No hot spot mutazionale
• Quasi tutte in eterozigosi (D90A omozigosi)
• Mai riportato coinvolgimento delle funzioni
cognitive
SOD1
In 1873, however,
Charcot reported that ALS was never hereditary, and he
used this principle to delineate ALS from spinal muscular
The view that ALS is rarely familial has persisted for several years. However over the last 30 year it has become clear that about 5-10% of ALS cases have strong hereditary component
For many complex diseases,including alzheimer and PD, familiality rates
are of the order of 5 to 10%.However many of these studies contain flaws, making them
Unreliable. The first one in absence of standard definition for FALS
As show in this recent paper from the same groun in which an online questionnaire was sent to clinicians
involved in the diagnosis and management of ALS.
Respondents were then provided with eight pedigrees and
asked whether they would diagnose the proband with FALS.
.
Although the majority of respondents agreed that having one other affected family member with ALS was sufficient to
constitute a diagnosis of FALS, opinions differed as to whether
this relative should be at the very least a first-degree relative,
a second-degree relative or any relative, no matter how distant.
The great majority of our FALS cases (40/53, 75.5%) were families with only two affected relatives (Figure 1), a frequency significantly higher than that previously reported in a cohort of FALS families from France and Canada (50 %).9 Different opinions exist as to whether these patients should be classified as FALS. 4 In fact, the possibility exists that two family member can develop ALS from different causes, including genetic factor of couse, but also common environmental factor or simply by chance
that a second person within a kindred is affected by chance if one person already has ALS may not be excluded.9 Traditional Mendelian patterns of inheritance , was recognized in a minority of families.
recognized
The possibility exists the two family members may develops ALS from different causes, including genetic factors, common environmental factors or syply by chance.
The great majority of our FALS cases (40/53, 75.5%) were families with only two affected relatives (Figure 1), a frequency significantly higher than that previously reported in a cohort of FALS families from France and Canada (50 %).9 Different opinions exist as to whether these patients should be classified as FALS. 4 In fact, the possibility that a second person within a kindred is affected by chance if one person already has ALS may not be excluded.9 Traditional Mendelian patterns of inheritance , was recognized in a minority of families.
recognized
But, on the other hand , under the assumption of polygenic inheritance, the
number of predicted apparently sporadic cases is high
The results of this study provide an empirical confirmation of this hypothesis, showing that genetic components due to the currently known major ALS genes exist on a continuum, ranging from fully penetrant phenotypes to apparently sporadic cases.
besides a lower mean age of onset
We have analyzed 480 SAL patients in which genealogies have been
actively investigated,
Figure 3 | Pleiotropy of genes associated with ALS. Hereditary ALS is not a ‘many
genes, one degenerative syndrome’ situation. No ‘ALS gene’ has exclusively been
associated with an ALS-only motor phenotype. The figure illustrates the reported
relationships between mutations in different genes and selected clinical
syndromes. The arrows point to the dominant clinical feature relevant to ALS.
Abbreviations: ALS, amyotrophic lateral sclerosis; AOA2, oculomotor apraxia
type!2; FTD, frontotemporal dementia; HSP, hereditary spastic paraparesis; PLS,
primary lateral sclerosis; PMA, progressive muscular atrophy, POAG, primary open
angle glaucoma; SMA, spinal muscular atrophy.
L144F: Classica
These data suggest that most ALS cases are probably due to oligogenic inheritance, perhaps
in combination with environmental factors but monogenic inheritance is also possible
We have analyzed 480 SAL patients in which genealogies have been
actively investigated,
These data suggest that most ALS cases are probably due to oligogenic inheritance, perhaps
in combination with environmental factors but monogenic inheritance is also possible