2. Physiology of lipid digestion and absorption
Hypobetalipoproteinemia
3.
4. Triacylglycerol -90-95%
Phospholipids-
Sterols
Others ( Fat soluble vitamins)
Iqbal J et al Am J Physio Endocrino Metab2009
5. Triacyglcerol –
Oleic acid and Palmitate dominant fat
ingested
Maximum energy derived from it
Phospholipids-
10-20 gm/day from bile
1-2 gm/day from diet
Sterol-
Cholesterol- animal origin
Sitosterol- plant origin non absorbsle
6. Oral cavity- Lingual Lipases-TG
Stomach- Lingual and Gastric enzymes and
Emulsification
Duodenum- Mixing with Bile and Pancreatic
Juice, Hydrolysis and Micellization
Jejunum-Absoption along mucosa in upper
2/3 part.
7. Lipid must pass through three physical
Phases for absorption:
Water in the lumen,
Lipid in the epithelial membrane,
Water in the lymphatics and bloodstream.
More than 95% of ingested fat is absorbed by
adults.
Sleisenger & Fordratans Text book of Gastroenerology 9thEd
12. 3 Class of lipids:
CLASS- 1
CLASS -2
CLASS-3
Yong Hi et al Immun, Endo & Metab Agents In Med Chem,2009
13.
14. Non-polar Lipids Octadecane, carotene, squalene,
cholesteryl oleate, cholesteryl
linoleate, and paraffin oil.
Polar Lipids: I Triacylglycerols,
diacylglycerols, long-chain
protonated fatty acids, and fat-
soluble vitamins
Polar Lipids:II Phospholipids, monoacylglycerols,
monoethers, and alphahydroxy
fatty acids.
Polar Lipids:IIIA Sodium salts of long-chain fatty
acids, many anionic, cationic and
nonionic detergents, and
lysophosphatidylcholine
Polar Lipids:IIIB Bile salts, sulfated bile alcohols,
and saponins .
15. Hydrophobic (Class-I)coated with hydrophilic
components( Class-II & IIIB)
Phospholipids,bile salts acts as emulsifier as
well as mechanical activity in stomach
19. Unstirred Water Layer
An unstirred water layer is present on the
surface of the intestinal epithelium, which in
humans is approximately 40 μm deep.
This layer may be rate limiting for uptake
of long-chain fatty acids but not for short-
or medium chain fatty acids.
20.
21.
22.
23.
24. Cholesterol esters, in the presence of bile
salts andcalcium, are hydrolyzed by carboxyl
ester lipase (CEL) (pancreatic cholesterol
esterase) to release the free sterol, in which
form it is absorbed.
Abumrad NA et al Physiol Rev 2012
25.
26.
27. Apolipoproteins are proteins which combines
lipid componant to form lipoproteins.
They makes lipid carriable in Aqueous media
34. Premucosal-Bile, Pancreas, Stomach
Mucosal-
Decrease mucosa
Disorganised
Diseased mucosa
Normal mucosa with internal defects
Postmucosal-Lymphatic Blockage
Mayo clinic Board Review for Gatroenterology 4th Ed
35. Quantitative test Van de Komer test ( Gold Standard)
Semiquantitive test Acid steatocrit testing
Qualitative test Sudan III staining
Breath test C14 olein breath test
Serum test B carotene levels
36.
37. TERMINOLOGY
INTRODUCTION
CLASSIFICATION
PRIMARY CAUSES
SECONDARY CAUSES
PATHOPHYSILOGY
EPIDEMILOGY
CLINICAL FEATURES
LABORATORY FEATURES
DIAGNOSIS
POSSIBLE TRATMENTS
38. Neuroacanthocytosis syndromes
Hypolipidemia
Hypocholesterolemia
Hypobetalipoproteinemia
Hypotrigycedemia
Jung et al. Orphanet Journal of Rare Diseases
2011, 6:68
Minicocci et al J Lip Res 2013
39. Hypobetalipoproteinemia is group of heterogenous
disorder comprising disorders characterised by
reduced plasma levels of Total Cholesterol , LDL- C,
and Apo B.
Hypolipidemia is defined as a total cholesterol (TC) <
120 mg/dL (< 3.1 mmol/L) or low-density
lipoprotein (LDL) cholesterol < 50 mg/dL (< 0.13
mmol/L).
The Merck Manual of Diagnosis & Therapy,
19th Edition
The Lipid Research Clinics population prevalence
study's fifth percentile for LDLC (<75 mg/dL) and TC
(< 130 mg/dL) also taken as cutoff in one study
Glueck CJ et al Metabolism 1997
41. Primary –
Dominant- FamilialHypobetalipoproteinemia
Recessive- Abetalipoproteinemia
Chylomicron Retension Disease
Primary orphan HBL
Secondary-
Diet, Drugs, Disease related
Tarugi P et al Advan Clin Chem 2011
42. Liver and Intestine are main site of Apo B
production
Apo B play primary role in transport of
cholesterol and triglyceride
Two forms in plasma-Apo-B48 and Apo-
B100
Kane JP et al The Metab & Mol
basis Vol-II 2001
43. Apo B100 – 4538 AA ( Chr-2)
Full length transrcibed form
Forms component of VLDL,IDL,LDL.
Apo B48- 2152 AA.
Synthesized in intestine
Essential for Chylomicron formation.
It is result of post translational modification
of Apo 100 mRNA inserting stop codon.
Kane JP et al The Metab & Mol
basis Vol-II 2001
44. Once formed Apo B undergo Lipidation
It is two step process
In first step partially trancsribed Apo B undergo partial lipidation that
prevent degrading.
During full transcrption ApoB go in to ER where full lipidation occurs
with help of MTP (CHR-4).
After this it go to Golgi complex for excretion
A specialised transport system transports ER derived vesicles to Golgi.
It is mediated by Coat protein II.
One of the subunit of this Cop II is essential
In human this is Sari Gtpase( CHR-5).
Mutation in it cause CMRD
Gibbons GF et al Bio Soc
Trans 2004
Hussain MM et al Curr Opi
Lipidol 2005
45.
46. Availability of Lipid at ER
Characteristics of Apo B- Length, Signal
peptide polymorphism,Apo B folding
Microsomal trigyceride transfer protein
Cellular stress
LDL-R- increasing internal digestion
LDL-R -degrading LDL by incr uptake-PCSK-
9
Ginseberg HN et al J Lip
Res 2009
Sundaram M et al Nutr
Metab 2010
47. FHBL
-Defected Apo B Secretion-
Truncated Apo B
Mutant with high affinity to MTP
-Increased Liver uptake-
PCSK9 inactivation
52. FHBL- 9:10,000 Anderson et al Acta Pedia Scanda 1979
1:3000 Welty FK et al Arterio Thrombo
Vasc Bio 1998
1:500-1:1000 Linton MF et al J Lipidio Res
1993
ABL- < 1 In One million
CMRD- Very Rare
53. Clinical phenotype varies
Depends upon residual function of- Apo B
lipoproteins
In general recessive forms more severe than
dominant
54. Heterozygoates asymptomatic
But most of them develop fatty liver and mild
int. malabsortion
In Homozygoate and Compo hetrozygoates
phenotype depends upon severity
55. Fatty liver-
-54% Prevalence
-Fivefold increase in TG content
-Mechanism-
VLDL particles smaller than normal not
excreted
Less than normal Apo-B 100 from normal
allele.
Sankatsingh et al Arterioscler. Thromb. Vasc. Biol.2005
56. Cardiac
No prospective study
Noninvasive markers encouraging
In PCSK9 Patient study shows reduction
Cancer risk
Reverse causality
57. NATURAL HISTORY
At birth – infant normal and neonatal period
uncomplicated
After neonatal period patients develop steatorrhoea
and abdo distension
Diagnosis of Celiac Ds made and kept on GFD diet
As child grows fat restricted diet become apparent
and fat soluble vitamin deficiencies starts to appear
At end of first decade clumsiness, ataxia,
Misdiagnosed as Fredrich’s
At puberty retinal degeneration appears
At adult life varied clinical syndromes ,patient may
develop cardiovascular abnormalities
58. Classical triad
Retinitis
Ataxia
Loss of deep tendon reflexes
In infancy steatorhhoea- treated as celiac
No response to GFD
Failure to thrive
Acanthocytoisis
59. Later in life neurological manifestations-
Post column neuropathy,
Myopathy,
Spinocereballar ataxia
Coagulopathy
Retinitis pigmentosa
Anemia
Associations
Ileal adenocarcinoma
Metastatic spinal cord glioblastoma
Fatty liver
62. Vegetarians
CLD
Chr Pancreattis
ESRD on Hemodialysis
Hyperthyroidism
B thallasemia
Sickle cell disease
Cancer
Nonspecific chronic illness
Undernutrition or malnutrition
Severe infection
HIV infection
Malabsorption
Repetitive plasmapheresis
63.
64.
65.
66.
67.
68.
69.
70. Fat loading done after 6 hr fast in small
children and 12 hr fast in large childern
2gm/kg margarine given
Blood withdrawn at 0,2,4 hr
The rise of plasma TG levels >55mg/100 ml
(>0.6 mmol/1) at 2 hr can discriminate
between patients with gastrointestinal
disease and normal controls or patients with
functional disturbances.
Jonas A et al Archives of Disease in Childhood, 1979
71. GENE CARD TEST FOR ABL-
100% sensitive
100% specific
Burnett JR et al Euro J Human
Gen 2012
72. Dietary restriction of Fat in Infancy esp. with
that of LCFA level. Havel RJ et al Meta Basis of Inher
Disease 6th Ed 1989
MCT can be used – but poor carrier for fat
soluble vitamins and risk of hepatic fibrosis
Illingworth DR et al
Metabolism 1979
5gm Veg oil cont Ess fat Acids. Kayden Persn
Communications
As age increase dietary fat absortption
increase and can be taken as much as
tolerated- 60-70 gm can tolerated
73. Vita E-100-300mg/day
Kayden HJ et al . Adv. Exb. Med. Biol. 201:
67-81. 1985
Oral soluble Vitamin A-200-400 IU/kg day
Illingworth DR Arch. Neuml. 1980
Vit K if required