Part 1 The A to Z on Amyloidosis (Terms, Diagnosis, Types, Treatment, Genetic & Gut)

(Amyloidosis Support Group, October 2019, Conference Notes)

Diagnosis

Terms

Amyloidosis = Protein folding disorder
TTR = transthyretin: Transports thyroxine (a thyroid hormone) and retinol (vitamin A). Also known as Prealbumin
Over 95% of TTR is produced in the liver. But some is produced by the eye and brain (choroid plexus).
ATTR = amyloid TTR (abnormal TTR, misTTR, the TTR than misfolds)
ATTR production can be caused by one of over 100 genetic mutations (hereditary ATTR (hATTR, ATTRh, ATTRm (m=mutant))), or by age (wild type ATTR, (ATTRwt, wtATTR)).
About 4% of African Americans have hATTR, with the mutation TTR V122I)

Other (non-ATTR) hereditary amyloidosis

See Hereditary systemic amyloidosis in “Organ Transplant as therapy” section below.
General information
Amyloid deposits look white, so they look like starch, which is why it got the name Amyloid.
When the protein is mis-folded, it is sticky – it sticks together, creating insoluble fibrils that resist degradation – but the mis-folded TTR has binding sites for Congo red stain, so we can use Congo red stain to detect it.
The body’s protein quality control systems break down proteins. With age, our quality controls become less effective, so older people can get “wild type” amyloidosis, with mis-folded proteins not getting cleared out, and building up, to create problems.
How amyloidosis is usually diagnosed:
  1. First, Congo red stain helps detect it
  2. Secord, laboratory tests determine the type of amyloidosis
Additional tests may support the diagnosis
Differential diagnosis (other diseases that look like Amyloidosis)
Proteinuria/nephritic syndrome in adults may be caused by:
  1. Focal and Segmental Glomerular Sclerosis/Minimal change disease
  2. Membranous nephropathy
  3.  Diabetes
  4. Amyloidosis
Detecting amyloidosis
Earlier on, amyloidosis was not easily detected with Congo red seeing as there were not as much misfolded protein to detect.
Where do we investigate with Congo red? Could do the effected organ, but testing in body fat can be better. Early diagnosis can result in much better outcomes, but is difficult to achieve.
ATTR detection in fat:
Sensitivity is 54-93% = chance of detecting it, if it is there
Specificity is 93-100% = chance of having a negative test, if you do not have ATTR
Testing in fat is easy, but a biopsy of heart muscle will be more sensitive (more likely to detect disease, if it is present)
Wild Type
TTR protein becomes unstable with age, and gets stuck in various places in your body, causing problems.
Alternate names for wild type amyloidosis
Senile Cardiac Amyloidosis (SCA)
Senile Systemic Amyloidosis (SSA)
Age-related Cardiac Amyloidosis
Wild type generally hits around age 70, but can hit in the 40s or 50s
How proteins are made
RNA in your body’s cells help Amino acids join together to form proteins. The folding creates the “secondary structure”, and then folds further to create the “tertiary structure”. TTR has 4 proteins, so they fold ever more, forming a “quadrinary structure”. The mid-folded TTR protein happens to be folded such that it sticks to other TTR proteins. We don’t know yet why it tends to accumulate in certain places, like the heart.
The heart wall gets infiltrated with the mis-folded amyloid, getting thick and stiff, so the heart can’t beat as well.
Wild type vs. hereditary ATTR – who gets which?
Age (Years) ; ATTRm (Variable) (depends on mutation) | ATTRwt >65 y.o
Gender (% M| % F); ATTRm 50% | 50% | ATTRwt 95%| 5%
Race (To date); Depend of mutation | Predominantly Caucasian
Affected Organs; Nerves, Heart, Eyes | Heart
Ejection Fraction in Cardiac Amyloidosis
Ratio of blood out vs. total blood held in heart – in amyloidosis patients, outwardly it looks fine (Because the heart holds less blood to start – the denominator is small), even though the blood volume ejected is small.
PYP scans can detect amyloid in the heart
Treatment
Restrict Salt! – the mainstay, along with diuretics
Atrial Fib – use a blood thinner, maybe for life
Calcium channel blockers – maybe. For some patients, these can cause more harm than good.
Hypertension – compression stockings and midodrine
AICD / pacer (use of a pacemaker) – More of a role for pacing
New drugs
Tafamidis – FDA approved for Amyloidosis treatment. Expensive.
Diflunisal – Not FDA approved for Amyloidosis treatment. Cheap. Not good for patients with certain conditions:
no recent decompensation
Good renal function
Daily diuretic dose < 80 mg Lasix, no metolazone
Use with anticoagulation
*Several other medications are approaching approval

 hATTR – hereditary amyloidosis

* Overview of Hereditary Transthyretin Amyloidosis (hATTR) Frederick L. Ruberg, MD Amyloidosis Center, Boston University School of Medicine
Alternate names of hATTR
Also called “Variant TTR” or “mutated TTR”, familial amyloid polyneuropathy (FAP), familial amyloid cardiomyopathy (FAC) (see later slides)
How the body makes proteins
DNA, made of nucleotides, guides the formation of RNA, which guides the formation of proteins
A series of 3 nucleotides form one of twenty amino acids, which are strung together into proteins.
DNA mutations
Polymorphism – the differences between people
In DNA, polymorphisms can be a change in nucleotides. Sometimes this doesn’t matter, but sometimes it changes how the protein that in produced.
TTR is on chromosome 18 (chromosome – a bunch of DNA). If the wrong nucleotide is in a certain place on this, you can have hereditary ATTR (amyloid TTR)
Effects of different types
ATTR affects heart and nervous system, in general. But there is a lot of variability. Different mutations have different sets of symptoms. For instance:

Source: Maurer, Circulation: Heart Failure 2019
Same type may manifest differently in different people

Source: https://hattramyloidosis.co.uk/en-gb/symptoms

How common is ATTR
50,000 worldwide with manifest disease.
V122i occurs in about 3.5% of African Americans, 150,000 over age 65 at highest risk for hATTR.
Even at Boston, a top center for ATTR, it goes undetected. We need to keep increasing doctors’ awareness.
Distribution of different types of ATTR varies by country.
Type affects treatment
Different types need different treatments.
Knowing your type
  • “23&me” genetic testing looks for a few TTR mutations
  • What do we tell children of those diagnosed with hATTR symptoms? Doctors are still unsure of when to start therapy/ therapy for those with the genetic mutation, but still without symptoms.
Disease progression and tests

 

  • See Dr. Maurer et al. paper about progressive testing and treatment: “Expert Consensus Recommendations for The Suspicion And Diagnosis Of Transthyretin Cardiac Amyloidosis” Maurer, Circulation: Heart Failure 2019.
  • 1st guidelines for Amyloidosis! From ASNC: how to use imaging testing to detect ATTR
Early signs
Orthopedic manifestations – early sign of ATTR? Tests of tissue removed during carpel tunnel showed about 10% with ATTR, 2 which were hATTR (Sperry, Hanna JACC 2018)
 Signs
Bilateral carpal tunnel
Spinal Stenosis
Spontaneous biceps tendon rupture
Conclusions
hATTR results from a single base pair change in the TTR gene, that causes a change in the TTR protein resulting in misfolding and amyloid fibril formation
hATTR is passed down to children in an autosomal dominant manner (50% chance of passage)
The type of mutation determines the predicted symptoms and organ systems that are affected
Determination of genotype is critical to selecting treatment
We must move toward early identification to give treatments the best chance to work
Organ Transplant Therapy ; Angela Dispenzieri, M.D., Professor of Medicine & of Lab. Medicine, Mayo Clinic.
Transplant basics
Used in some ATTR, and other amyloidosis types (AFib, …)
The liver produces TTR, but is generally not affected by the ATTR.
Hereditary Systemic Amyloidosis 

FIBRIL NAME | MUTATED PRECURSOR PROTEIN | TARGET TISSUE

ATTR | Transthyretin | PNS, ANS, heart, eye, leptomeninges, tenosynovium

AFib | Fibrinogen a-chain | Kidney

ALys | Lysozyme | Kidney (primarily)

AApoAI | Apolipoprotein A-I | Heart, liver, kidney, PNS, testis, larynx, skin

AApoAII | Apolipoprotein A-II | Kidney

AGel | Gelsolin | PNS, cornea

ACys | Cystatin C | PNS, skin

ABri | Abri-PP | CNS

Ab2M | b2-microglobulin | Musculoskeletal system

What to do with involved organs
  1. Replace the liver – the main source of most of these proteins
  2. Replace the affected organs (heart, kidney, … – but we can’t replace nerves or skin)
  3. Do both
Liver transplants
Liver ATTR transplants:
1st liver transplant for ATTR done in 1990
1st domino transplant for ATTR in 1995
1st partial liver transplant for ATTR in 1995
Domino transplant
ATTR pt gets new liver, ATTR pt’s liver goes to someone else who would not get one otherwise (but it may produce hATTR in the recipient, even within 10 years, so that needs to be considered).
Partial liver transplants
family member gives part of their liver to the person with ATTR.
Does liver transplant cure the disease? Not always
Symptoms may continue to get worse, even after transplant. Why? It seems like normal TTR may stick to ATTR, if ATTR has already accumulated.
ValMet30 pts usually DO get better after transplant
Other types have smaller portion of pts getting better after transplant:
ATTR wild-type: replacing the liver does not affect things – the problem is in cleaning up TTR is the body, not in what is produced.
10 year survival rate varies by type of ATTR:

page15image2378896656 page15image2378896848 page15image2378897104

Val30Met early onset (85%)
Val30Met late onset (45%)
Val71Ala (N) (85%)
Leu111Met (H) (83%)
Leu58His (H/N) (76%)
Thr60Ala (H/N) heart & liver (58%)
Thr60Ala (H/N) liver Tx only (36%)
Ser50Arg <50% (less than 50%)
Ser77Phe <50%
Ser77Tyr <50%
Glu89Gln <50%
Tyr114Cys <50%
Note: Quality of life may be poor after a transplant.
Will organ transplant make a difference?
We don’t know for sure. The ATTR type gives us some clue, but there are still uncertainties. Some of the new drugs may help, with or without a liver transplant.
What we know:
Survival improved with liver transplant in V30M. But would the new drugs help even more?
Most effective if early. But how early?
Major benefit in nutrition
Combined “liver + heart” or “liver + kidney” feasible

What we don’t know:

When is organ transplant futile?
Which mutations benefit? (most benefit seems to be in early onset V30M, V71M, L111M, L58H)
With heart involvement, do patients need combined heart and liver? And if so, in what order?
Should transplant patients get new drugs?
Transplants may help some non-ATTR types:
Fibrinogen A (not ATTR) – Liver transplant had some promising data
AApoA-1 (among 16 kidney transplant cases, 10 year graft survival was 77%)
ALys (among 3 kidney transplant cases, all grafts functioning between 0.9 and 6.2 years) ALECT2 – weak evidence supports kidney transplants
But we need more evidence around these.
Drugs or transplant?
Transplants have waiting lists, can be very debilitating, and have many side effects. We hope that medications will become effective and safe enough that transplants won’t be needed.
Dr Morie – had patient that had liver transplant that was provided then gene silences Tx which seemed to trigger rejection of the transplant.
Genetic counselling (Katie Agre, MS, LCGC agre.katie@mayo.edu Licensed Certified Genetic Counsellor)
Genetics basics
Change a gene, change a person’s characteristic, like eye color. Variation in genes is natural.
Genetic testing helps identify whether ATTR is hereditary or not. That has implications for your blood- line family members (i.e., if yours is hereditary, they likely to be at high risk for ATTR).
Why do genetic testing?
Confirm whether the amyloidosis in your family is genetic vs. wildtype
Impacts treatment and eligibility to clinical trials
Necessary for testing of family members
Can provide information about what to expect medically
Why talk to a genetic counselor?
Genetic counselors discuss: many things, but especially how to talk to family members about your condition, support (like ASG), the chance they have it, and a concise, useful package of information (vs. the rabbit-hole of disorganized, confusing information they may find on the internet).
Genetic counsellors prepare you for the various ways your family members may react
Your children may or may not want to be tested. That is a personal choice. Just knowing that you have the genetic abnormality affects how folks think
o Should I change my retirement plans?
o Does this affect my plans for having kids?
o Does this point me toward other lifestyle changes?
o How do I share this information with a partner? A fiancé? Do I talk about it on the 1st date? After our honeymoon?
o Relatives who are negative may feel something like “survivor’s guilt”.
Once you know your gene status, you can’t un-know it, so the decision to get tested is personal, and merits being made thoughtfully, after being well-informed.
Genetic testing can allow for earlier diagnosis, which may have advantages given the availability of treatments.
Who else is at risk?
1st degree relatives (siblings, children, parents) have 50% change of carrying the gene mutation Other relatives may also have the mutation
Sharing information about risk?
Open communication!
Family letter
Other resources, like Amyloid Support Group website, http://amyloidosissupport.org/
Identify the family communicator
You know your family best!
page16image2399327168 page16image2399327360
Discussing genetic testing with un-tested family members
Genetic testing is a personal choice
Think about implication of knowing
Make sure your loved ones are informed about risks, benefits, and logistics of testing PRIOR to getting tested,
Get tools to adapt and share information with family
Things to consider before getting tested
How will I feel if I am not at risk?
How will I react if I am positive?
How will I use this information?
Am I able to handle the impact of the positive result?
Is now the right time?
Insurance implications
Insurance often covers the cost of the testing
 The Gut
 GI involvement
Amyloid can affect anywhere in the GI tract.
It can affect the outer layer, middle, or inner layer of gut (intestine)
Inner layer – diarrhea
Muscles – constipation, small intestine bacterial growth (stuff isn’t pushed through fast enough, bad bacteria increases)
Nerves – Motility coordination decreases – so stuff can move fast or slow, so constipation or diarrhoea, nausea.
Vascular – bleeding
Symptoms per place along the digestive tract affected
Symptoms are linked to area of involvement & are often non-specific
Esophagus
Reflux
Dysphagia
Food impaction
Stomach
Abdominal pain
Nausea Vomiting Distention
Small intestine
Diarrhoea
Malabsorption
Weight loss
Pseudo-obstruction
Colon
Diarrhoea
Constipation
Fecal incontinence
Diagnosing causes of GI problems
Most symptoms of amyloidosis are NOT specific to amyloidosis. Most are very common, and are usually caused by a lot of other diseases, or side-effects of many medications.
Endoscopy, colonoscopy, biopsies – can only detect types that manifest in the inner layer of the intestine.
Imaging – gut thickness, …Usually reserved for testing if initial tests don’t indicate the cause Motility studies – … Usually reserved for testing if initial tests don’t indicate the cause
Treatment options
Small bowel – usually, a wave of muscle contractions moves material out of the small bowel every 90 minutes. If amyloid hinders that, bacteria can build up, creating gas & other symptoms.
Esophagus
Reflux treatment options
Dietary modification
Antacids
Histamine receptor blockers
Proton pump inhibitors
Endoscopic/surgical options in carefully selected patients
Dysphagia treatment options
Dietary modification
Dilatation
Botox
Stomach
Dietary modification
Prokinetics
Metoclopramide (Reglan)
Erythromycin/azithromycin Domperidone (not FDA-approved)
Prucalopride
Bethanechol
Pyridostigmine
Agents to help stomach expansion
Herbal therapies (peppermint/caraway)
Buspirone
Neuromodulators
Tricyclics (amitriptyline)
Mirtazapine (Remeron)
Gabapentin (Neurontin)
Gabapentin/pregabalin (Lyrica)
Anti-emetics
Endoscopic options: Botox
Small bowel
Dietary modifications
Prokinetics
Antibiotics (focused on small intestinal bacterial overgrowth) Octreotide
Steroids
Bile-salt binding agents
Anti-diarrheal
Imodium
Lomotil
Tincture of opium
Parenteral nutrition (rare cases)
Colon
Dietary modifications
Laxatives
Over the counter
Miralax
Senna
Magnesium-based preparations
Prescription
Lubiprostone (Amitiza) Linaclotide (Linzess) Plecanatide (Trulance)
Prucalopride (Motegrity)*
Prokinetics
Epidemiology
Studies found less that 45% of ATTR pts with GI symptoms had ATTR detected in GI biopsies. Biopsies often won’t reach the affected parts of the GI tract.
Conclusions
Amyloid can cause symptoms by either direct deposition or nerve involvement
Only the mucosa can be evaluated by endoscopy so the absence of amyloid on endoscopic biopsy does not exclude amyloid involvement
Involvement appears to be common (60%) in familial amyloidosis, particularly in neuropathic variants
Diagnostic options & treatment options exist and can be customized to specific symptoms
Print Friendly, PDF & Email

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.

%d bloggers like this: