screening genetici per individuare ipercolesterolemia ... solo cuore... · screening genetici per...

Di.M.I. University of Genoa

IRCCS AOU SAN MARTINO-IST

Screening genetici

per individuare

ipercolesterolemia

familiare

Livia Pisciotta

CASO CLINICO

Il sig. PM di anni 47 in buona salute, non fumatore,

normoteso, normopeso. Una sera esce di casa per

andare a correre…

REFERTO AUTOPTICO:

…Coronarie: coronarosclerosi stenosante della

coronaria sinistra (risuzione del lume di circa 90%)

coronarosclerosi della coronaria destra: riduzione del

lume di circa il 50-60%)…

La causa di morte del sig. PM è da indentificarsi in una

insufficienza cardiaca acuta con EPA terminale in

soggetto affetto da coronarosclerosi di grado severo

In seguito all’evento, il fratello, il sig. PW di anni 46

anche lui in buona salute, non fumatore, normoteso,

normopeso, decide di effettuare esami ematochimici e

cardiologici:

Viene rilevato:

colesterolo totale 410 mg/dl

HDL 60 mg/dl

LDL 314 mg/dl

TG 180 mg/dl

ECG da sforzo: positivo per ischemia inducibile

Coronarografia: coronaropatia ostruttiva per cui

viene eseguita angioplastica coronarica in elezione

i figli del sig. PM, in buona salute, normopeso,

vengono valutati:

La ragazza di 15 anni presenta:


HDL 67 mg/dl

LDL 114 mg/dl

TG 69 mg/dl

Il ragazzo di 13 anni presenta:


HDL 56 mg/dl

LDL 176 mg/dl

TG 161 mg/dl

Ripetuto dopo alcuni giorni:


HDL 58 mg/dl

LDL 143 mg/dl

ripetuto dopo tre mesi:

Colesterolo totale 173 mg/dl

HDL 73 mg/dl

LDL 90 mg/dl

TG 48 mg/dl

ripetuto dopo tre mesi:


HDL 58 mg/dl

LDL 129 mg/dl

TG 64 mg/dl

ApoB 95 mg/dl

ApoA 139 mg/dl

Si procede con l’analisi del gene LDLR mediante

sequenziamento sul sig. PW per poi effettuare

l’eventuale “screening a cascata” sui nipoti

LDL B LDL b

LDL B

LDL B

LDL B

HEPATOCYTE

PLASMA

ADH-1 ADH-2 ADH-3

PCSK9 (GOF)

LDLR

47 y

13 y

40 y

15 y

LDL-C 90 LDL-C 129

Famiglia P.

Mutazione

LDLR Asp151>Gly

IMA

46 y

LDL-C 314

mieloma

69 y

HCH

89 y

CHD

37 y

9

HeFH: DIAGNOSTIC CRITERIA

Bertolini S, Pisciotta L et al.

Probability score according to the

clinical criteria of the Dutch Lipid

Clinic Network (DLCN):

-473 subjects (46.5%): “definite ADH”

-257 (25.2%): “probable ADH”

-288 (28.3%): “possible ADH”

In the group of 1018 index subjects, mutations in the

candidate genes were detected in 832 individuals (809

Italians and 23 of different ethnicities) with a mutation

detection rate of 82%.

-811 (97.4%): LDLR mutations (ADH-1),

-18 (2.2%): APOB mutations (ADH-2)

-3 (0.36%): PCSK9 mutations (ADH-3),

Mutation detection rate stratified according to DLCN score

“definite ADH” 435/473 (91.9%) 8.1% NO GEN.DIAGNOSIS

“probable ADH” 197/257 (76.6%)

“possible ADH” 200/288 (69.4%)

RESULTS: Mutation detection

Of 14 subjects classified as “definite HE-ADH” :

i) 12 resulted homozygotes (HO) or compound

heterozygotes (CHE) for mutations in LDLR

gene (8 HO and 4 CHE, respectively)

ii) 2 resulted double heterozygotes for

mutations in APOB and LDLR genes (one

subject) or for mutations in PCSK9 and LDLR

genes (one subject).

Prevalence and clinical impact of FH variants in a large U.S. clinical care cohort.

Noura S. Abul-Husn et al. Science 2016;354:aaf7000

FH variants are associated with increased LDL-C levels.


FH variants are associated with increased risk of CAD.


Presequencing likelihood of FH diagnosis with DLCN criteria.


When genetic diagnosis

can be useful ?

In homozygous phenotype

1. Plasma LDL-C level >13 mmol/L

(500 mg/dl)

2. Tendon and cutaneous xanthomas

in infancy

3. Hystory of hypercholesterolemia in

both parents

CLINICAL CRITERIA FOR HO-FH

EAS Consensus Panel statement on homozygous FH Stock J. Atherosclerosis 2015; 242: 323-6

*

In heterozygous phenotype

LDL-C levels in 1250 genetically characterized

heterozygous FH patients (values are adj. for gender and age)

LDL-C (mg/dL)

<150 175 200 225 250 275 300 325 350 375 400 425 450 475 500 >500

Bertolini S. 2011

Median 273.4 mg/dL

10th p. 205.5 mg/dL

25th p. 234.8 mg/dL

50th p. 273.4 mg/dL

90th p. 358.4 mg/dL

75th p. 317.6 mg/dL

5th p.189.3 mg/dL

95th p. 391.0 mg/dL

Prevalence of Tendon Xanthomatosis (%)

in 1116 FH patients in relation to age

Age (years)

-

FCHL LDLR +

N. 21/143 (14.7%)

M/F 10/11

Age (years) 45.812.1

BMI (kg/m2) 27.03.6

Tc (mg/dl) 365.055.4

HDLc (mg/dl) 46.619.6

Tg (mg/dl, median, range) 247 (147-810)

Spanish FCHL subjects positive for mutations in LDLR gene

TG ≤ 200 mg/dl TG > 200 mg/dl P

N. 585 78 (11.7%)

M/F 260/325 41/37 NS

Age (years) 48.912.0 51.110.9 NS

BMI (kg/m2) 24.23.4 26.73.4 0.0001

Tx (%) 47.2 53.2 NS

CAD (%) 30.6 39.7 NS

TC (mg/dl) 375.763.9 413.370.1 0.0001

LDL-C (mg/dl) 302.163.4 324.166.2 0.004

HDL-C (mg/dl) 51.313.9 42.410.6 0.0001

TG (mg/dl,

median, range) 112 (31-200) 244 (202-432) 0.0001

Comparison between FH subjects over 30 y of age with

pathogenic LDLR gene mutations according TG levels

Factors involved in TG

increase

Mutations in the LDLR repeat 5 (IDL binding)

common variants in LPL, APOA5, APOC3

genes such as (for example D9N and N291S,

or –1131 T>C and c.56 C>G (S19W)…

APOE 2 or 4 allele

Insulin resistance

…

In recessive phenotype

GENE Disease

LDLRAP1 ARH

ABCG5/G8 Sitosterolemia

LIPA LAL-D

Familial Hypercholesterolemia

(Recessive forms)

40 y

16 y

40 y

LDL-C 171

Apo B 120

LDL-C 104

Apo B 80

76 y

43 y

72 y

LDL-C 77

Apo B 52

LDL-C 115

Apo B 78

noTx; 1V-CAD,

PTCA

LDL-C 347

Apo B 178

LDLR c.328 G>C (Ex 4)

p.Cys109Ser (repeat 3)

19 y

LDL-C 92

Apo B 72

LDL-C 318

Apo B 195

LDLR c.28 T>A (Ex 1)

p.Trp10Arg (SP)

De novo LDLR gene mutations

(differential diagnosis with ARH)

In absence of family’s data

9 y

LDL-C 162 mg/dl

SMG 9 anni adottato vietnamita

In anamnesi Epatite B

In buona salute, normopeso

ABCG5 EX 3 Val113 FS c.335_336 Ins A

ABCG5 EX 3 Leu110>Gln c.329 T>A

In corso dosaggio di sitosteroli

SANGER SEQUENCING OF CANDIDATE GENEs

GENE PRICE

LDLR (18 exons) 640 euros

APOB ex26

(1 exon) 40 euros

PCSK9 (12 exons) 480 euros

Tot. 1160 euros

NGS (NEXT GENERATION SEQUENCING)

ALL GENES 300 euros

Italian Society of Atherosclerosis, LIPIGEN e Network Italiano delle

Dislipidemie Genetiche

http://www.sisa.it/LIPIGEN/

CONCLUSIONS

DIAGNOSIS OF FH IS A CLINICAL DIAGNOSIS

THE PHENOTYPE IS DETERMINANT IN THERAPEUTICAL

DECISIONs

GENETIC DIAGNOSIS, when available, CAN BE USEFUL

in HOMOZYGOUS PHENOTYPE, IN YOUNG PATIENTs, for

DIFFERENTIAL DIAGNOSIS with FCHL, for DIFFERENTIAL

DIAGNOSIS in RECESSIVE PHENOTYPE or in ABSENCE OF

FAMILY’S DATA

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