Copper- sources, daily requirement, absorption, transportation, storage, excretion, role in enzymatic action, role in iron metabolism, role in elastin maturation, role in bone formation, copper deficiency, copper toxicity, Wilson disease, Menkes disease.

1. Copper- Chemistry, functions
and clinical significance
Namrata Chhabra
MHPE, MD, CMCL FAIMER FELLOW
REGIONAL INSTITUTION,
Principal-in charge, Professor& Head, Department of Biochemistry,
SSR Medical College, Mauritius

2. Case study
• A 15 –year-old girl presented with abdominal pain and diarrhea for 3
days.
• She became jaundiced and a presumptive diagnosis of infective
hepatitis was made, but serological tests were negative.
• She subsequently died of fulminant liver failure.
• At post-mortem, her liver copper concentration was found to be
grossly increased.
• What is the probable diagnosis?

3. Case details
• High liver copper concentration, indicates that the patient died of
Wilson’ disease,
• It is an autosomal recessive disorder.
• Clinical manifestations are caused by copper toxicity.
• The condition is characterized by excessive deposition of copper in
the liver, brain, and other tissues.
• The major physiologic aberration is excessive absorption of copper
from the small intestine and decreased excretion from the liver.

4. Copper Metabolism
• Copper is an essential trace element which is a component of many
intracellular metalloenzymes.
• Copper is present in all metabolically active tissues.
• The highest concentrations are found in liver and kidney, with
significant amount in cardiac & skeletal muscles and bones.
• The liver contains 10% of the total body content of 80mg.
• Fetal liver contains approximately ten times more copper than adult
liver.

5. Sources of copper
Average diet provides 2 to 4 mg/day of copper in the form of :
• Meat,
• Shellfish,
• Legumes,
• Nuts and cereals
• Milk and milk-products are poor sources.

6. Daily Requirements
• Infants and children: 0.05 mg Cu/kg body wt. per day
• Adult requirement: approximately 2.5 mg/day.
• Normal diets contain about 2.5 to 5.0 mg Cu.

7. Absorption, storage and excretion
• Primarily absorbed from the duodenum.
• About 32% of the dietary Cu can be absorbed.
• Phytates, Zinc, heavy metals and high amount of Vitamin C inhibit
Copper absorption.
• A low molecular weight substance from human saliva and gastric juice
complexes with Cu++ to keep it soluble at pH of intestinal fluid.
• In the intestinal mucosal cells, Cu is associated with low molecular
weight metal binding protein called as metallothionein.

8. Plasma copper
• It is exported from the enterocytes into the blood by Cu-ATPase ATP7A and
transported via the portal vein to the liver, which is the main organ
responsible for copper homeostasis.
• Absorbed Cu is transported in plasma bound to amino acids, particularly
histidine and albumin at a single strong binding site.
• In less than an hour, the absorbed Cu is removed from the circulation by
liver.
• In hepatocytes and other cells, copper is absorbed by copper transporter 1
(CTR1).
• In the cytoplasm, it is bound to metallothionein or to copper-specific
chaperone proteins. Thus, cells are protected from the toxic effects of free
copper.

9. Role of Liver in Copper homeostasis
Liver processes absorbed Cu through two routes:
1. Excretion of Cu in bile
• Copper homeostasis is maintained almost exclusively by biliary
excretion, human urine contains only traces of Cu.
• Excess copper is first excreted in bile and then into gut,
• The fecal copper output(12.5 μmol/24 hours), is the sum of the
unabsorbed dietary copper and that of the re-excreted copper.

10. Role of Liver in Copper homeostasis
2. Synthesis of Ceruloplasmin
Caeruloplasmin, a glycoprotein is synthesized exclusively by liver.
Most of the copper in plasma is bound to Caeruloplasmin.
Ceruloplasmin exhibits a copper-dependent oxidase
(ferroxidase)activity, which is associated with possible oxidation of Fe2+
(ferrous iron) into Fe3+ (ferric iron), therefore assisting in its transport
in the plasma in association with transferrin, which can carry iron only
in the ferric state.

11. Serum Copper
Serum Cu is present in two distinct forms:
1. Loose form of Cu: Which is loosely bound to albumin. Approximately
4 per cent of copper is present in this form.
2. Bound form: Which remains bound to Caeruloplasmin. About 96 per
cent of serum Cu is found in combination with caeruloplasmin.

12. Forms of Copper
It occurs as:
1. Erythrocuprein (in red blood cells),
2. Hepatocuprein (in liver) and
3. Cerebrocuprein (in brain).

13. Functions of copper
• Role as a cofactor in enzyme action
Cu forms an integral part of certain enzymes, such as:
• Cytochromes,
• Cytochrome oxidase,
• Tyrosinase,
• Monoamine oxidase (MAO),
• Lysyl oxidase,
• Catalase, Ascorbic acid oxidase, uricase and super-oxide dismutase
etc.

14. Functions of copper
2. Role of Copper in Fe absorption and transportation of iron
• Copper participates in the iron absorption
• Additionally, Cu helps in the utilization of Fe for Hb synthesis
• Caeruloplasmin’, catalyzes the oxidation of Fe++ to Fe+++. This helps
in the incorporation of Fe in “transferrin” to facilitate mobilization and
utilization of Fe.

15. Functions of copper
3. Role in Maturation of Elastin:
Copper helps to form insoluble elastin fibers by cross-linking soluble
• Pro-elastin chains through the oxidation of some lysine residues.
• Pro-elastin rises significantly in copper deficient animals.

16. Functions of copper
4. Role in Bone formation and synthesis of myelin Sheath :
Copper has been reported to assist in the formation of bones
and maintenance of myelin sheaths of nerve-fibers.

17. Copper deficiency
• Both children and adults can develop symptomatic copper deficiency.
• Premature infants are the most susceptible since copper stores in
liver are laid down in the third trimester of pregnancy.
• In adults copper deficiency is found in intestinal bypass surgeries or in
patients who are on parenteral nutrition.
• Symptoms range from bone disease to iron resistant microcytic
hypochromic anemia.

18. Copper toxicity
• Copper toxicity is uncommon and is mostly due to administration of
copper Sulphate solutions.
• Oral copper Sulphate may lead to gastric perforation.
• Serum copper may be greatly elevated.
• Copper is toxic to many organs, but renal tubular damage is more
common and is of major concern.
• Treatment is by chelation with Penicillamine.

19. Wilson’s disease
• The condition is characterized by excessive deposition of copper in
the liver, brain, and other tissues.
• The major physiologic aberration is excessive absorption of copper
from the small intestine and decreased excretion of copper by the
liver.
• Patients with Wilson disease usually present with liver disease during
the first decade of life or with neuropsychiatric illness during the third
decade.

20. Biochemical defect
• The genetic defect has been shown to affect the copper-transporting
adenosine triphosphatase (ATPase) gene (ATP7B) in the liver.
• Many of the gene defects for ATP7B are small deletions, insertions, or
missense mutations.
• Most patients carry different mutations on each of their 2
chromosomes.
• More than 200 different mutations have been identified, the most
common of which is a change from a Histidine to a glutamine
(H1069Q).

21. Pathophysiology
• The processes of incorporation of copper into ceruloplasmin and
excretion of excess copper into bile are impaired.
• The transport of copper by the copper-transporting P-type ATPase is
defective secondary to one of several mutations in the ATP7B gene.
• P-type ATPases use the energy from ATP hydrolysis to pump ions
across the cell membrane against a concentration gradient.
• The excess copper acts as a promoter of free radical formation and
causes oxidation of lipids and proteins.
• Initially, the excess copper is stored in the liver and causes damage to
the hepatocytes.

22. Pathophysiology
• Defective copper incorporation into apo Ceruloplasmin leads to
excess catabolism and low blood levels of Ceruloplasmin.
• Serum copper levels are usually lower than normal because of low
blood Ceruloplasmin, which normally binds >90% of serum copper.
• As the disease progresses, non-Ceruloplasmin serum copper ("free"
copper) levels increase, resulting in copper buildup in other parts of
the body, such as the brain, leading to neurologic and psychiatric
disease.

23. Pathophysiology

24. Clinical Manifestations
1. Hepatic manifestations
• Wilson disease may present as hepatitis or liver cirrhosis
• An episode of hepatitis may occur, with elevated blood transaminase
enzymes, with or without jaundice, and then spontaneously
regresses.
• Hepatitis often reoccurs, and most of these patients eventually
develop cirrhosis.

25. Clinical Manifestations
• Neurologic manifestations
• Typically occur in patients in their early twenties,
although the age of onset extends into the sixth
decade of life.
• The three main movement disorders include:
dystonia, incoordination, and tremor.
• Sensory abnormalities and muscular weakness are
not features of the disease.

26. Clinical Manifestations
3) Psychiatric manifestations
• Behavioral disturbances are present in half of
patients with neurologic disease.
• The features are diverse and may include loss of
emotional control (temper tantrums, crying
bouts), depression and hyperactivity.

27. Clinical manifestations
• Other Manifestations
• Sunflower cataracts and Kayser-Fleischer
rings (copper deposits in the outer rim of
the cornea) may be seen.
• Electrocardiographic and other cardiac
abnormalities have been reported but are
not common.

28. Diagnosis
• The presence of Kayser-Fleischer rings and caeruloplasmin levels of
less than 20 mg/dL in a patient with neurologic signs or symptoms
suggest the diagnosis of Wilson disease.
• If a patient is asymptomatic, exhibits isolated liver disease, and lacks
corneal rings, the coexistence of a hepatic copper concentration of
more than 250 mg/g of dry weight and a low serum ceruloplasmin
level is sufficient to establish a diagnosis.

29. Laboratory Studies
• Serum ceruloplasmin
• Approximately 90% of all patients with Wilson disease have
ceruloplasmin levels of less than 20 mg/dL (reference range, 20-40
mg/dL).
• Falsely low ceruloplasmin levels may be observed in any protein
deficiency state, including nephrotic syndrome, malabsorption,
protein-losing enteropathy, and malnutrition.

30. Laboratory Studies
• Urinary copper excretion
• The urinary copper excretion rate is greater than 100 mg/d
• Hepatic copper concentration
• This test is regarded as the criterion standard for diagnosis of Wilson
disease.
• A liver biopsy with sufficient tissue reveals levels of more than 250
mcg/g of dry weight even in asymptomatic patients.
• Imaging Studies- CT and MRI of brain and abdomen can be carried
out to confirm the diagnosis

31. Treatment
• Medication
• The mainstay of therapy for Wilson disease is pharmacologic
treatment with chelating agents. Chelating agents bind excess copper
• Ammonium tetra thiomolybdate
• Penicillamine
• Trientine
• B6 and Dimercaprol can also be used as a part of the treatment.

32. Treatment
• Anti-copper therapy must be given for life long.
• With treatment, liver function usually recovers after about a year,
although residual liver damage is usually present.
• Neurologic and psychiatric symptoms usually improve between 6 and
24 months of treatment.

33. Complications
• The major complications in patients with untreated Wilson disease
are those associated with :
• liver failure and
• a chronic, relentless course to cirrhosis.

34. Summary
• 1) Wilson’ disease is an autosomal recessive disorder caused by mutations in
the ATP7B gene, a membrane-bound copper transporting ATPase.
• 2) In this disease, the processes of incorporation of copper into ceruloplasmin
and excretion of excess copper into bile are impaired.
• 3) Patients with Wilson disease usually present with liver disease during the
first decade of life or with neuropsychiatric illness during the third decade.
• 4) The diagnosis is confirmed by measurement of serum caeruloplasmin,
urinary copper excretion, and hepatic copper content, as well as the detection of
Kayser-Fleischer rings.
• 5) The mainstay of therapy for Wilson disease is pharmacologic treatment with
chelating agents like; Ammonium tetra thiomolybdate, Penicillamine, zinc and
Trientine.

35. Menkes syndrome
• Menkes syndrome is a disorder that affects copper levels in the body.
• Synonyms-Copper Transport Disease
• Kinky Hair Disease
• Steely Hair Disease
• Trichopoliodystrophy
• X-linked Copper Deficiency

36. Menkes syndrome
• It is characterized by sparse, kinky hair; failure
to gain weight and grow at the expected rate
(failure to thrive); and deterioration of the
nervous system.
• Additional signs and symptoms include weak
muscle tone (hypotonia), sagging facial
features, seizures, developmental delay, and
intellectual disability.

37. Menkes syndrome
• The affected infant may also appear to have a yellow appearance
(jaundice) which is caused by excessive bilirubin in the blood
(hyperbilirubinemia).
• Lower than normal body temperature (hypothermia) also may occur
in the neonatal period. The normal, asymptomatic phase of the illness
typically lasts for two to three months.
• Children with Menkes syndrome typically begin to develop symptoms
during infancy and often do not live past age 3.
• In rare cases, symptoms begin later in childhood.

38. Pathophysiology
• Menkes syndrome is inherited in an X-linked recessive pattern
• Mutations in the ATP7A gene cause Menkes syndrome.
• Mutations in the ATP7A gene result in poor distribution of copper to
the body's cells.
• Copper accumulates in some tissues, such as the small intestine and
kidneys, while the brain and other tissues have unusually low levels of
copper.
• The decreased supply of copper can reduce the activity of numerous
copper-containing enzymes that are necessary for the structure and
function of bone, skin, hair, blood vessels, and the nervous system.

39. Diagnosis
• The diagnosis of MD is suggested by the appearance of brittle,
tangled, sparse, steely or kinky hair at several months of age.
• Blood tests showing low levels of serum copper and ceruloplasmin
support the diagnosis.
• Measurement of plasma catecholamine levels helps in early diagnosi.
• Molecular genetic testing for mutations in the ATP7A gene is an
efficient method of population-based newborn screening.
• Carrier testing and prenatal diagnosis are also available once a
specific ATP7A gene variant has been identified in an affected family
member.

40. Treatment
• There is no complete cure for Menkes disease at this time, but
treatment with parenteral copper histidinate (CuHis) can increase
survival and lessen the neurological symptoms if initiated early, within
approximately 28 days following birth.
• One-time adeno-associated viral gene therapy in combination with
subcutaneous CuHis injections represents a promising treatment
approach in development for subjects with Menkes disease.

42. Thank you
16-Jul-21 Our Biochemistry 42