Transcript HFE

Genes and Metabolic Liver
Disease: Hemochromatosis
Bruce R. Bacon, M.D.
James F. King M.D. Endowed Chair in Gastroenterology
Professor of Internal Medicine
Division of Gastroenterology and Hepatology
Saint Louis University Liver Center
St. Louis, Missouri
History of Hemochromatosis
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1865 – Trosier – first case
1889 – von Recklinghausen – hemochromatosis
1935 – Sheldon – inherited defect in iron metabolism
1976 – Simon – HLA-A3, short arm chromosome 6
1996 – Mecator Genetics – HFE
1997 – present
− DMT-1
− Ferroportin
− Transferrin receptor-2
− Hemojuvelin
− Hepcidin
Classification of Inherited Iron
Overload Syndromes
• Hereditary Hemochromatosis
– HFE-related
 C282Y/C282Y
 C282Y/H63D
 Other HFE mutations
– Non-HFE-related
 Hemojuvelin (HJV)
 Transferrin receptor-2 (TfR-2)
 Ferroportin (SLC40A1)
 Hepcidin (HAMP)
 African iron overload
Classification of Iron Overload
Syndromes - 2
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•
Secondary Iron Overload
– Iron-loading anemias
 Thalassemia major
 Sideroblastic
 Chronic hemolytic anemia
 Aplastic anemia
 Pyruvate kinase deficiency
 Pyridoxine-responsive anemia
– Parenteral iron overload
 Red blood cell transfusions
 Iron-dextran injections
 Long-term hemodialysis
– Chronic liver disease
 Porphyria cutanea tarda
 Hepatitis C
 Hepatitis B
 Alcoholic liver disease
 Nonalcoholic steatohepatitis
 Following portocaval shunt
– Dysmetabolic iron overload syndrome
Miscellaneous
– Neonatal iron overload
– Aceruloplasminemia
– Congenital atransferrinemia
HFE Genotype in Patients with Hemochromatosis
Study
Feder,
et al.
Beutler,
et al
Jouanolle,
et al.
Jazwinksa,
et al.
Carella,
et al.
Adams and
Chakrabarti
Bacon,
et al
Country
USA
USA
France
Australia
Italy
Canada
USA
178
147
65
112*
75
128
66
C282Y
C282Y
148 (83)
121 (82)
59 (91)
112 (100)
48 (64)
122 (95)
60 (91)
C282Y**
H63D
8 (4)
8 (5)
3 (5)
0
2 (2.27)
2 (1.6)
1 (1.5)
C282Y
Wild Type
1 (0.5)
2 (1)
0
0
2 (2.27)
2 (1.6)
1 (1.5)
H63D
H63D
1 (0.5)
2 (1)
1 (1.5)
0
1 (1.3)
0
0
H63D
Wild type
7 (4)
4 (3)
2 (3)
0
3 (4)
0
2 (3)
Wild Type
Wild type
13 (7)
10 (7)
0
0
16 (21)
4 (3.1)
1 (1.5)
No. of Patients
Genotype n(%)
*All patients had a family history of iron overload
** Compound heterozygote
Ser65  Cys, S65C
His63  Asp, H63D
 Heavy Chain
1
2-microglobulin
2
NH2
NH2
3
Extracellular
Plasma membrane
Cytosol
HOOC
Nature Genetics 13: 309-408, 1996
Cys282  Tyr, C282Y
HOOC
HFE Genotype in Patients with
Hemochromatosis
• Patients with hemochromatosis
– 771 patients with phenotypic HH
– 670 (86.9%) with C282Y/C282Y
– 44 (5.7%) with C282Y/H63D
– 24 (3.1%) with C282Y/wt
Incidence of Hereditary
Hemochromatosis
• 1 in 200 - 250 individuals of Northern
European descent
• 11% heterozygotes
• Estimated 600,000 to 1,000,000 afflicted
Americans
• Estimated 27 million heterozygotes
Hereditary Hemochromatosis Diagnosis
Requirements of Diagnosis
• Suspicion, serum iron studies
• Liver biopsy
• Use of HII
• Differential diagnosis
–Alcoholic liver disease
–Chronic viral hepatitis
–Nonalcoholic steatohepatitis
– Genetic test
Typical Symptoms in
Patients with HH
%
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Weakness, lethargy, fatigue
Apathy, lack of interest
Abdominal pain
Weight loss
Arthralgias
Loss of libido, impotence
Amenorrhea
Congestive heart failure symptoms
40-85
40-85
30-60
30-60
40-60
30-60
20-60
0-40
Common Physical Findings in HH
• Hepatomegaly
• Cirrhosis
• Skin pigmentation
%
60-85
50-95
40-80
• Arthritis (second, third
metacarpophalaneal joints)
40-60
• Clinical diabetes
• Splenomegaly
• Loss of body hair
10-60
10-40
10-30
• Testicular atrophy
• Dilated cardiomyopathy
10-30
0-30
Hereditary Hemochromatosis
Symptoms and Physical Findings (%)
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No symptoms
Lethargy, and/or weakness
Loss of libido, impotence
Arthralgias
Diabetes
Skin pigmentation
Am J Gastroenterol 92:784-789, 1997
73
25
12
13
5
5
Principal Clinical Features in Hereditary Hemochromatosis
Features
Milder
et al.
1980
Edwards
et al.
1980
Niederau
et al.
1985
Adams
et al.
1991
Bacon &
Sadiq
1997
34†
35*
163*
37‡
40
Weakness, lethargy
73
20
83
19
25
Abdominal pain
50
23
58
3
0
Arthralgias
47
57
43
40
13
Loss of libido, impotence
56
29
38
32
12
Cardiac failure symptoms
35
0
15
3
0
Cirrhosis (biopsy)
94
57
69
3
13
Hepatomegaly
76
54
83
3
13
Splenomegaly
38
40
13
-
-
Loss of body hair
32
6
20
-
-
Gynecomastia
12
-
8
-
-
Testicular atrophy
50
14
-
-
-
Skin pigmentation
82
43
75
9
5
Clinical diabetes
53
6
55
11
-
Number of subjects
Symptoms (#)
Physical and Diagnostic Findings (%)
* Patient selection occurred by both clinical features and family screening.
† Only symptomatic index cases were studied.
‡ Discovered by family studies.
Zakim Boyer, 1996;1453.
Evaluation of Iron Stores
• Serum iron, TF saturation and ferritin
• Liver biopsy for stainable iron, biochemical
determination of iron
• Noninvasive imaging modalities
– Computed tomography
– Magnetic resonance imaging
– Magnetic susceptibility
• Iron removed by phlebotomy (1 U=250 mg)
Blood Iron Studies in HH
Normal
HH
• Serum iron (µg/dl)
50-150
180-300
• Transferrin (mg/dl)
250-370
200-300
20-50
80-100
Males
20-300
500-6,000
Females
15-250
500-6,000
• Transferrin saturation (%)
• Serum ferritin (ng/ml)
Hemochromatosis –
Role of Liver Biopsy
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In the past – establish diagnosis
Determine degree of fibrosis, cirrhosis
Determine other abnormalities
Phenotypic variability
Recommended if:
– Ferritin > 1000 ng/mL
– ALT, AST elevated
– Hepatomegaly
– Age > 40 years
Therapeutic Phlebotomy
for HH
• Clearly improves survival
• Prepare patients for up to 6 – 12 months
• Iron burden in men greater than in women
despite initial HIC
• Difficult to predict phlebotomy requirements
• Each unit of blood – approximately 30 ng/mL
ferritin
Therapeutic Phlebotomy
for HH
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Weekly phlebotomy
Hct. > 35% before each one
Ferritin to 50 to 100 ng/mL
Transferrin saturation to < 50%
Maintenance Phlebotomy
for HH
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Most patients – one unit Q 2-3 months
TS < 50%; ferritin < 100 ng/mL
One unit of whole blood = 250 mg iron
Most patients absorb 2 to 3 mg/day, more
than needed
• Some patients – no re-accumulation
Hereditary Hemochromatosis
Response to Therapy
Edwards et al. Ann Int Med 93:519-525, 1980
Results of Therapy
• Reduction to normal tissue iron stores.
• Improved survival if diagnosis and treatment before development of
cirrhosis and diabetes.
• Improved sense of well-being, energy level.
• Improved cardiac function.
• Improved control of diabetes.
• Reduction in abdominal pain.
• Reduction in skin pigmentation.
• Normalization of elevated liver enzymes.
• Reversal of hepatic fibrosis (approximately 30% of cases).
• No reversal of established cirrhosis.
• Reduction in portal hypertension in cirrhotics.
• No (or minimal) improvement in arthropathy.
• No reversal of testicular atrophy.
Hereditary Hemochromatosis:
Survival
N Engl J Med 313:1256-1262, 1985
Hereditary Hemochromatosis:
Survival with Cirrhosis
N Engl J Med 313:1256-1262, 1985
HH – Family Screening
• HFE mutation analysis has replaced HLAtyping
• Practically – HFE mutation analysis, TS, and
ferritin all at once
HH – Family Screening
• For analysis of risk in children – perform
mutation analysis in spouse (or other parent)
first
• May be able to avoid testing in children
Adams, Clin Genet 53:176-178, 1998
General Population Studies in HH
• Transferrin saturation, ferritin, CBC
• HFE mutation analysis
• Several studies from around the world
Population Screening for
Hemochromatosis
• 41,038 adults screened in San Diego
• Health appraisal unit
• CBC, transferrin saturation, ferritin level,
HFE genotype
• Questionnaire
Beutler et al., Lancet 359:211-218, 2002
Population Screening for
Hemochromatosis
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152 C282Y/C282Y
616 C282Y/H63D
67% of C282Y/C282Y had elevated ferritin
No difference in symptoms from controls
1 of 152 with signs and symptoms of
hemochromatosis
Beutler et al., Lancet 359:211-218, 2002
Population Screening for Hemochromatosis
Beutler et al., Lancet 359:211-218, 2002
Prevalence of C282Y Homozygotes Without
Iron Overload in Screening Studies
Country
n
Prevalence of
homozygotes
C282Y
homozygotes
with a normal
ferritin (%)
Electoral roll
New Zealand
1,064
1 in 213
40
Primary care
USA
1,653
1 in 276
50
Epidemiological survey
Australia
3,011
1 in 188
25
Blood donors
Canada
4,211
1 in 327
81
General public
USA
41,038
1 in 270
33
North America
44,082
1 in 227
25
Australia
29,676
1 in 146
32
124,636
1 in 240
41
Population sample
Primary care
General public
Total
Hereditary Hemochromatosis
• Patients with C282Y/C282Y mutation without iron
overload
– Environmental factors
 Nutritional deficiency, malabsorption
 Gastrointestinal blood loss
 Menstrual blood loss
 Pregnancy
– Genetic factors
 Hepcidin
 DMT-1
 Ferroportin
 TfR-2
 Hemojuvelin
 Others
Hereditary Hemochromatosis
• Patients with iron overload
– 10% to 15% are negative for C282Y/C282Y
– Mutations in other genes
 Ferroportin
 TfR-2
 Hepcidin
 Hemojuvelin
 Others
Iron Overload Syndromes
• Ferroportin (SLC40A1)
– 2q32
– Autosomal dominant
– RE cell distribution
– African iron overload, Solomon Islanders
– Pedigree described
Pietrangelo et al., NEJM 341:725-732, 1999
Montosi et al., JCI 108:619-623, 2001
Gordeuk et al., Blood Cells Mol Dis 31:299-304, 2003
Iron Overload Syndromes
• Transferrin receptor-2 (TfR-2)
– 7q22
– Autosomal recessive
– Parenchymal cell distribution
– Pedigree described
Hoffman et al., Blood 100:1099-1100, 2002
Iron Overload Syndromes
• Hepcidin (HAMP)
– 19q13.1
– 25 amino-acid peptide
– Juvenile iron overload (rarely)
– Autosomal recessive
– Parenchymal cell distribution
– More importantly – principal “hormone”
involved in iron regulation
Roetto et al., Nat Genet 33:21-22, 2003
Iron Overload Syndromes
• Hemojuvelin (HJV)
– 1q21
– Juvenile iron overload
– Autosomal recessive
– Parenchymal cell distribution
– Pedigree described
Fleming and Bacon, NEJM 352:1741-1744, 2005
Hereditary Hemochromatosis
• Genetic testing for non-HFE HH
• InVitae, San Francisco Genetic Testing Company
– HFE
– HAMP – hepcidin
– HFE-2 – hemojuvelin
– SLC40A1 – ferroportin
– TFR2
• $1500 per order, 2 weeks
• 415-374-7782
• [email protected]
Hereditary Hemochromatosis
Summary
• In 2013…
– Most patients with hemochromatosis do not
need a liver biopsy
– Only about 60% of C282Y homozygous
patients have phenotypic expression
– About 25% of C282Y homozygous men have
signs or symptoms of hemochromatosis
– Detailed gene testing available