Transcript 2G Conditions that are still important

2G Conditions that are still
important - G6PD Deficiency and
Galactosaemia
Tina Yen
Chemical Pathologist
AIMS/AACB Beckman BBQ
17th February 2015
[email protected]
Case 1
• Baby AT Female
DOB 24-6-14
• Parents consanguineous (India). Previously 3
miscarriages.
• Born 38 + 6 and birth weight 2680g at Auburn
Hospital. Uneventful.
• Return to Auburn on day 6 with jaundice.
Presentation day 6
• Appeared markedly jaundiced, lethargic and
vomiting after feed.
• serum BR 406 umol/L; LFTs abnormal.
– ALP
– AST
– INR
839
236
7.8
U/L
U/L
• Started phototherapy.
• Review of newborn screen (NBS) suggested
galactosaemia.
• Transferred to Children’s Hospital Westmead.
• Repeat NBS testing
• Absent of galactose-1-phosphate uridyltransferase
enzyme activity.
• Classical Galactosaemia
• Treatment
– 2 x FFP transfusions
– Vit K
– IV antibiotics but stopped when no growth on cultures.
• On discharge – markedly LFTs improved (sBR 24 with
direct 12; ALP 283, AST 36, INR 1.1). Weight increasing
slowly. Parents counselled about lifelong adherence to
galactose free diet.
Case 2
• 9 day old baby boy
• Emergency Department
• Term baby, 600 g marked weight loss and jaundice
• Total BR
442
• Conjugated BR
74
• Unconjugated bilirubin 368
umol/L
umol/L
umol/L
• Additional Information
• Random glucose
1.9 mmol/L
• (Urine reducing substances +++)
(0 ‐ 10)
Conjugated Hyperbilirubinaemia
in Infancy
• Caused by biliary obstruction, either within
or without the liver
• Caused by damage to hepatocytes
• Caused by a combination of obstruction
and secondary damage to hepatocytes
Causes of Conjugated
Hyperbilirubinaemia
• Extrahepatic obstruction
• Extrahepatic biliary atresia
• Choledochal cyst
• Intrahepatic obstruction
• Alagille syndrome (arteriohepatic dysplasia)
• PFIC - progressive familial intrahepatic cholestasis
(PFIC), classified into three types. Type 1 is also
called Byler disease.
• Bile acid synthesis defects
• Dubin-Johnson syndrome
Causes of Conjugated
Hyperbilirubinaemia
• Infection
• Viruses
• Cytomegalovirus (CMV) the most common
• Toxoplasmosis
• Syphilis
• Metabolic/Inherited
•
•
•
•
•
Alpha1-antitrypsin deficiency
Tyrosinaemia Type 1
Galactosaemia
Fructose Intolerance
Peroxisomal (Zellweger) and Mitochondrial disorders
Causes of Conjugated
Hyperbilirubinaemia
• Other Genetic
• Cystic Fibrosis
• Endocrine disorders
• Adrenal Insufficiency
• Hypopituitarism
• Total Parenteral Nutrition
• Neonatal Iron Storage Disease
• Idiopathic Neonatal Hepatitis
Is the pattern of hyperbilirubinaemia,
hypoglycaemia and positive urine
reducing substances a diagnostic clue?
• YES
• NO
Essential Diagnostic Sample (hypoglycaemia)
• Collected from child during hypoglycaemic episode
• plasma glucose < 2.6 mmol/L
• serum for GH, cortisol, insulin, bHB, free FA,
lactate, plasma NH3 and acylcarnitines.
• Urine ketones and reducing substances (galactose),
organic acids (urine metabolic screen), and urine drug
screen.
Yen T, RCPA AACB CPC 2010
Are “sugars” the only reducing
substances present in urine?
• YES
• NO
Urine Reducing Substances
• Urinary reducing substances can be identified by
a positive Clinitest reaction (blue to orange).
• Substances associated with a positive reaction
include:
•
•
•
•
•
glucose
galactose
lactose
pentose
homogentisic acid
• drugs associated with a positive reaction include
salicylates, levodopa, ascorbic acid, nalidixic
acid, tetracyclines
Galactosaemia
• Most common form of galactosaemia is deficiency of the
enzyme galactose-1-phosphate uridyltransferase (GALT)
GK
• 1. Galactose
Gal-1-Phosphate
• 2. Gal-1-P
GALT
• 3. UDP Galactose
GK = Galactokinase
epimerase
UDP Galactose + Glu-1-P
UDP Glucose
Urine
Galactitol
Galactosaemia
• Occurs about once in 60,000 births in Australia
(autosomal recessive)
• Causes vomiting, hypoglycaemia and liver
failure with introduction of lactose containing
milk feeds
• Gram negative sepsis is also a feature
• Hepatomegaly occurs and later cataracts
• Can be diagnosed by newborn screening
Do all states of Australia have Newborn
Screening for galactosaemia?
• YES
• NO
Acknowledgements
• Nilika Wijeratne
• John Coakley
• Tina Yen
G6PD DEFICIENCY
Case 3
Na
* 133
K
4.1
Cl
100
HCO3
* 27
Urea
4.9
Creatinine 33
135 – 145
3.5 – 5.5
95 – 110
18 – 24
2.0 – 6.7
13 – 41
Bili
* 158
Bili (conj) < 10
LDH
* 866
19 month old male, presenting with jaundice
1 - 15
1 - 10
313 - 618
Haemoglobin * 63
White cells
8.7
Platelets
308
MCV
77.8
MCH
24.1
RDW
* 15.6
Reticulocytes % 3.7
Reticulocyte abs 97
105 - 138
4.7 – 15.2
150 – 600
70 - 88
22 - 30
11 - 14
20 - 105
Haemoglobin * 63
White cells
8.7
Platelets
308
MCV
77.8
MCH
24.1
RDW
* 15.6
Reticulocytes % 3.7
Reticulocyte abs 97
105 - 138
4.7 – 15.2
150 – 600
70 - 88
22 - 30
11 - 14
20 - 105
Red cell enzymes
Red Cell G6PD * 0.0
Red Cell 6PGD * 5.3
5.8 – 10.2
6.0 – 9.0
Jaundice secondary to acute
haemolytic anaemia
• Glucose-6-phosphate dehydrogenase deficiency
• Fava beans
FAVISM
• G6PD deficient patients are very sensitive to
oxidative stress.
• Oxidative stress manifesting as rapid haemolysis
and may be also triggered by infections and
drugs.
• compounded by commonly used drugs known to
decrease the G6PD level (e.g. paracetamol,
aspirin, other NSAID, sulfonamides, nitrates).
Role of G6PD enzyme
• Reduction of peroxide to water by glutathione
peroxidase.
• supply of reduced glutathione to act as a reducing
agent.
• oxidized glutathione must be reduced by NADPH
• source of NADPH is hexose monophosphate shunt
(pentose phosphate pathway). The first step
requires glucose-6-phosphate dehydrogenase
(G6PD).
G6PD deficiency
• X-linked recessive
• exposure to the oxidative substances overwhelms
protective mechanisms causing haemolysis, often
severe and intravascular.
• condition may be present from birth, but much
variation in clinical severity due to differences in
mutations.
• G6PD deficiency occurs in 11% of African-Americans is
usually subclinical in life, other variants in
Mediterranean Caucasians may be catastrophic at
birth.
• incidence of G6PD deficiency varies from 0.1% in
Germanic/Slavic/Baltic types to 50% in Kurdish Jews.
Correct association of G6PD
enzyme subunits is dependent
on NADP binding.
Two NADP binding sites are
shown
ORANGE = “structural NADP”;
PINK = “catalytic NADP”.
Mutations that cause the most
severe disease phenotype occur
in the region of the “structural”
NADP binding site.
BLOOD 2008: 11, 16 – 24.
“Glucose-6-phoshate
dehydrogenase deficiency:
a historical perspective”
Ernest Beutler
“2G conditions”
• 50y ago 3 enzyme deficiencies that produce disease in
humans had been identified (all from human
erythrocytes).
• The enzymes:
– catalase
– galactose-1-phosphate uridyltransferase
– glucose-6-phosphate dehydrogenase (G6PD)
*
*
• Each was discovered in red blood cells
• G6PD deficiency is the only one that manifests as
hematologic disorder
• it was as a consequence of investigation of haemolytic
anaemia the enzymatic deficiencies were discovered.