hereditary transthyretin ( ttr ) amyloidosis is a life - threatening autosomal - dominant disorder characterized by peripheral neuropathy , autonomic dysfunction , heart and kidney failure , and other symptoms leading to death , usually within 10 years of the onset of disease .
it can be classified as early - onset and late - onset types , on the disease onset , before or after 50 years .
misdiagnosis is frequent in the disease with atypical presentations , including chronic inflammatory demyelinating polyradiculoneuropathy or motor neuron disorder .
amyloid deposits containing mutant ttr are the distinctive pathological characteristics . however , the sural nerve biopsies are negative for amyloid deposits in about half of the cases . at present ,
over 100 point mutations in the ttr gene have been identified , in which val30met is the most common in many countries .
the 5-year survival rate of patients who do not have the val30met mutation is significantly lower than that of patients with ttr val30met .
liver transplantation is the most effective treatment for the disease , especially for patients with val30met mutation .
hence , the early diagnosis of the disease is significant . in china , there were only a few reports of hereditary ttr amyloidosis families . for most of them , amyloid deposits in different tissues
were the initial cues for the consideration of the disease . in this article , we will report nine chinese patients from eight families with hereditary ttr amyloidosis .
clinical and necessary examination materials were collected from the nine patients of eight families with hereditary ttr amyloidosis at peking university first hospital from january 2007 to november 2014 .
all the research methods and investigational tools in this study were approved by the ethics committee of peking university first hospital .
the sural nerve biopsies were taken for eight patients and skin biopsies were taken in the calf / upper arm for two patients .
parts of the samples were fixed in 4% formaldehyde , paraffin - embedded , 8-m sections , and stained with hematoxylin and eosin , congo red , as well as luxol fast blue ( not for skin tissues ) .
other parts of the samples were fixed in 3% glutaraldehyde , postfixed in 1% osmium tetroxide , dehydrated through serial alcohol baths , and embedded in epon 812 ( electron microscopy sciences , usa ) .
semithin sections of sural nerve samples for light microscopy examination were stained with toluidine blue .
ultrathin sections of nerve and skin tissues for electron microscope examination were contrasted with uranyl acetate and lead citrate .
we got 5 ml of peripheral blood and extracted genomic dna by the method of salt precipitation .
polymerase chain reaction ( pcr ) primers for exons 14 of the ttr gene were designed using primer 3 software .
the experimental products were purified and then sequenced using the abi 3730xl automatic sequencing machine ( applied biosystems , usa ) .
the clinical manifestations of nine patients with hereditary ttr amyloidosis are shown in table 1 .
there were five males and four females , ranging in age from 25 to 85 years ( mean  standard deviation , 50.1  20.3 years ) , with the duration of disease ranging 120 years .
the initial symptoms were pure paresthesia of lower limbs in two patients , pure weakness of lower limbs in two , paresthesia and weakness of all limbs in one , bilateral dysacusis in one , dizziness resulting from orthostatic hypotension in one , alternating diarrhea and constipation in one , and dysarthria owing to glossohypertrophia in one . at the diagnostic time , all the patients had paresthesia except patient 9 , among them seven patients were with distal weakness , six patients were with proximal weakness .
dysautonomic manifestations included diarrhea / constipation in six patients , urinary incontinence in one patient , sexual dysfunction in one patient , and orthostatic hypotension in four patients .
clinical data of nine hereditary ttr amyloidosis patients + : with the symptom or sign ;  : without the symptom or sign ; ttr : transthyretin .
sensory nerve conduction velocity ( scv ) tests showed reduced amplitude or disappearance of sensory nerve action potential ( snap ) in four patients , slow scv combined with reduced snap in three patients , and only slow scv of median nerve in patient 5 .
motor nerve conduction velocity ( mcv ) tests showed reduced amplitude of compound muscle action potential ( cmap ) in one patient , slow mcv in one patient and slow mcv combined with reduced cmap in five patients , and normal mcv in one patient ( patient 5 ) .
patient 5 had a family history of autosomal - dominant inheritance [ figure 1 ] , in which the clinical phenotypes varied largely in different individuals .
one sister of patient 8 had numbness of four limbs and alternating constipation / diarrhea .
individual i-2 and ii-3 had very severe neuropathy in the early stage of disease and died at ages of 35 and 58 , respectively .
the sural nerve biopsies from the eight patients ( except patient 9 ) showed variable pathological changes [ figures 2 and 3 ] .
seven patients ( 1 , 2 , 3 , 4 , 6 , 7 , and 8) had severe loss of myelinated fibers , three ( 1 , 2 , and 4 ) of whom had amyloid deposits , while the other patients had no amyloid deposits from light and electron microscopic examinations .
amyloid deposits were present in the perineurium , endoneurium , and endoneurial arterioles in two patients ( 1 and 4 ) , and only in a single endoneurial arterioles in one patient ( 2 ) .
one patient ( 5 ) had nearly normal sural nerve and skin with no amyloid deposits from light microscopic examinations , but with amyloid deposits among the capillary from skin electron microscopic examinations .
one patient ( 9 ) had no skin amyloid deposits from light and electron microscopic examinations .
( patient 1 ) congo red stain demonstrates amyloid deposits at the endoneurium ( a ) , apple green birefringence by polarized light ( b ) .
toluidine blue stained sections show a marked loss of myelinated fibers ( c ) ( patient 3 ) and nearly normal sural nerve ( d ) ( patient 5 ) .
electron microscopy reveals amyloid deposits around sural nerve capillary ( a ) and high magnification of amyloid filament ( b ) in patient 4 .
different missense mutations in the ttr gene were identified in the eight families , including val30met ( patients 1 , 2 , 8 , and 9 ) , phe33leu ( patient 3 ) , ala36pro ( patient 4 ) , val30ala ( patient 5 ) , phe33val ( patient 6 ) , and glu42gly ( patient 7 ) .
the clinical manifestations of nine patients with hereditary ttr amyloidosis are shown in table 1 .
there were five males and four females , ranging in age from 25 to 85 years ( mean  standard deviation , 50.1  20.3 years ) , with the duration of disease ranging 120 years .
the initial symptoms were pure paresthesia of lower limbs in two patients , pure weakness of lower limbs in two , paresthesia and weakness of all limbs in one , bilateral dysacusis in one , dizziness resulting from orthostatic hypotension in one , alternating diarrhea and constipation in one , and dysarthria owing to glossohypertrophia in one . at the diagnostic time , all the patients had paresthesia except patient 9 , among them seven patients were with distal weakness , six patients were with proximal weakness .
dysautonomic manifestations included diarrhea / constipation in six patients , urinary incontinence in one patient , sexual dysfunction in one patient , and orthostatic hypotension in four patients .
clinical data of nine hereditary ttr amyloidosis patients + : with the symptom or sign ;  : without the symptom or sign ; ttr : transthyretin .
sensory nerve conduction velocity ( scv ) tests showed reduced amplitude or disappearance of sensory nerve action potential ( snap ) in four patients , slow scv combined with reduced snap in three patients , and only slow scv of median nerve in patient 5 .
motor nerve conduction velocity ( mcv ) tests showed reduced amplitude of compound muscle action potential ( cmap ) in one patient , slow mcv in one patient and slow mcv combined with reduced cmap in five patients , and normal mcv in one patient ( patient 5 ) .
patient 5 had a family history of autosomal - dominant inheritance [ figure 1 ] , in which the clinical phenotypes varied largely in different individuals .
one sister of patient 8 had numbness of four limbs and alternating constipation / diarrhea .
individual i-2 and ii-3 had very severe neuropathy in the early stage of disease and died at ages of 35 and 58 , respectively .
the sural nerve biopsies from the eight patients ( except patient 9 ) showed variable pathological changes [ figures 2 and 3 ] . seven patients ( 1 , 2 , 3 , 4 , 6 , 7 , and 8) had severe loss of myelinated fibers , three ( 1 , 2 , and 4 ) of whom had amyloid deposits , while the other patients had no amyloid deposits from light and electron microscopic examinations .
amyloid deposits were present in the perineurium , endoneurium , and endoneurial arterioles in two patients ( 1 and 4 ) , and only in a single endoneurial arterioles in one patient ( 2 ) .
one patient ( 5 ) had nearly normal sural nerve and skin with no amyloid deposits from light microscopic examinations , but with amyloid deposits among the capillary from skin electron microscopic examinations .
one patient ( 9 ) had no skin amyloid deposits from light and electron microscopic examinations .
( patient 1 ) congo red stain demonstrates amyloid deposits at the endoneurium ( a ) , apple green birefringence by polarized light ( b ) .
toluidine blue stained sections show a marked loss of myelinated fibers ( c ) ( patient 3 ) and nearly normal sural nerve ( d ) ( patient 5 ) .
electron microscopy reveals amyloid deposits around sural nerve capillary ( a ) and high magnification of amyloid filament ( b ) in patient 4 .
different missense mutations in the ttr gene were identified in the eight families , including val30met ( patients 1 , 2 , 8 , and 9 ) , phe33leu ( patient 3 ) , ala36pro ( patient 4 ) , val30ala ( patient 5 ) , phe33val ( patient 6 ) , and glu42gly ( patient 7 ) .
the present series confirmed polyneuropathy with different severity was the common symptoms of hereditary ttr amyloidosis . both early - onset and late - onset types of the disease
the initial symptoms were different among them , including paresthesia or weakness of limbs , dizziness , dysacusis , alternating diarrhea and constipation , and dysarthria .
similar to other reports , autonomic nervous dysfunction occurred in most patients , especially in early - onset hereditary ttr amyloidosis .
. local amyloid deposition or nerve compression , ischemia and siderosis due to leptomeningeal , and vascular amyloidosis explain acoustic dysfunction in such cases .
we also confirmed that macroglossia resulting in dysarthria may occur in the patients with hereditary ttr amyloidosis , though that is more common in patients with light - chain amyloidosis .
low amplitudes of cmap and snap in presented series indicated extensive axonal impairment , which are very common in hereditary ttr amyloidosis .
the demyelinating feature can not exclude the possibility of hereditary ttr amyloidosis . in our patient with predominant ophthalmologic symptoms and hearing loss ,
the ncv showed only mild median nerve involvement , indicating mild peripheral neuropathy for some patients with the disease .
about half of our patients did not show amyloid deposits , similar to other reports .
we have proved skin biopsy can show amyloid deposits among the capillary in sural nerve negative pathology for amyloidosis .
in addition , salivary gland biopsy , abdominal fat aspiration , and muscle biopsy can be used for the detection of amyloid deposits .
ttr should be tested in a wide clinical spectrum of progressive neuropathies even for patients with negative pathological findings . in keeping with other reports ,
endemic areas of hereditary ttr amyloidosis are portugal , japan , sweden , and brazil .
we found six different kinds of missense mutations in the ttr gene in present series , including val30met in three families in which all the patients were late - onset ones . in our patients
val30ala , ala97ser , and gly83arg are recognized as the most common amyloidogenic forms in chinese patients , but in our patients only val30ala appeared in one family .
the reasons explaining the discrepancy may be that patients with ttr gly83arg mutant , indicating solitary ocular vitreous amyloidosis , without the evidence of systemic involvement , often came from the department of ophthalmology , while ala97ser may be common in chinese patients .
some mutations indicating special clinical phenotypes such as familial carpal tunnel syndrome ( tyr114his ) and predominant cardiomyopathy ( ala45ser ) proved the genotype - phenotype correlation , while sometimes the same genotypes show different phenotypes just like the family of patient 5 .
the fact that there are large differences in penetrance in different populations may explain different family histories of our patients .
since there are many patients with negative pathological findings of amyloid deposits in the sural biopsy , ttr gene should be tested in a wide clinical spectrum of chronic progressive neuropathies in adulthood , especially with extra - neural features .
 background : mutations of transthyretin ( ttr ) cause the most common type of autosomal - dominant hereditary systemic amyloidosis , which occurs worldwide . to date , 
 more and more mutations in the ttr gene have been reported . 
 some variations in the clinical presentation are often observed in patients with the same mutation or the patients in the same family . 
 the purpose of this study was to find out the clinicopathologic and genetic features of chinese patients with hereditary ttr amyloidosis.methods:clinical and necessary examination materials were collected from nine patients of eight families with hereditary ttr amyloidosis at peking university first hospital from january 2007 to november 2014 . 
 sural nerve biopsies were taken for eight patients and skin biopsies were taken in the calf / upper arm for two patients , for light and electron microscopy examination . 
 the ttr genes from the nine patients were analyzed.results:the onset age varied from 23 to 68 years . 
 the main manifestations were paresthesia , proximal and/or distal weakness , autonomic dysfunction , cardiomyopathy , vitreous opacity , hearing loss , and glossohypertrophia . 
 nerve biopsy demonstrated severe loss of myelinated fibers in seven cases and amyloid deposits in three . 
 one patient had skin amyloid deposits which were revealed from electron microscopic examination . 
 genetic analysis showed six kinds of mutations of ttr gene , including val30met , phe33leu , ala36pro , val30ala , phe33val , and glu42gly in exon 2.conclusions:since the pathological examinations of sural nerve were negative for amyloid deposition in most patients , the screening for ttr mutations should be performed in all the adult patients , who are clinically suspected with hereditary ttr amyloidosis . 
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