Tomoyuki Uemichi

Hereditary renal amyloidosis with a novel variant fibrinogen.

Two families with hereditary renal amyloidosis were found to have a novel mutation in the fibrinogen A alpha chain gene. This form of amyloidosis is an autosomal dominant condition characterized by proteinuria, hypertension, and subsequent azotemia. DNAs of patients with amyloidosis were screened for a polymorphism in fibrinogen A alpha chain gene by single-strand conformation polymorphism analysis, and affected individuals from two kindreds were found to have a mutation. Both of these kindreds are American of Irish descent presenting with non-neuropathic, nephropathic amyloidosis in the fifth to the seventh decade of life. DNA sequencing showed a point mutation in the fibrinogen A alpha chain gene that is responsible for substitution of valine for glutamic acid at position 526. By restriction fragment length polymorphism analysis, 7 affected individuals and 14 asymptomatic individuals in these two kindreds were positive for the fibrinogen A alpha chain Val 526 gene. Fibrinogen was isolated from plasma of a heterozygous gene carrier and shown to contain approximately 50% variant fibrinogen. Discovery of this new mutation confirms the association between fibrinogen A alpha chain variant and hereditary renal amyloidosis and establishes a new biochemical subtype of amyloidosis.

Hereditary amyloid cardiomyopathy caused by a variant apolipoprotein A1.

Autosomal dominant hereditary amyloidosis with a unique cutaneous and cardiac presentation and death from heart failure by the sixth or seventh decade was found to be associated with a previously unreported point mutation (thymine to cytosine, nt 1389) in exon 4 of the apolipoprotein A1 (apoA1) gene. The predicted substitution of proline for leucine at amino acid position 90 was confirmed by structural analysis of amyloid protein isolated from cardiac deposits of amyloid. The subunit protein is composed exclusively of NH2-terminal fragments of the variant apoA1 with the longest ending at residue 94 in the wild-type sequence. Amyloid fibrils derived from four previously described apoA1 variants are composed of similar fragments with carboxyl-terminal heterogeneity, but contrary to those variants, which all carry one extra positive charge, the substitution Leu90Pro does not result in any charge modification. It is unlikely, therefore, that amyloid fibril formation is related to change of charge for a specific residue of the precursor protein. This is in agreement with studies on transthyretin amyloidosis in which no unifying factor such as change of charge for amino acid residues has been noted.

A trinucleotide deletion in the transthyretin gene (AV122) in a kindred with familial amyloidotic polyneuropathy

A 63-year-old white man of Ecuadorian origin had a subarachnoid hemorrhage at age 57 followed by numbness and paresthesia in his lower extremities. He subsequently developed sexual impotence, alternating constipation and diarrhea, urinary frequency, and difficulty in walking. Rectal biopsy revealed amyloid deposits immunohistochemi-cally reactive with antitransthyretin antisera. Direct DNA sequencing of the transthyretin gene of the patient showed a trinucleotide deletion in exon 4. This deletion resulted in the loss of one of two valines at position 121 or 122. DNA analysis on 11 family members at risk revealed four mutant gene carriers. Plasma transthyretin levels in the mutant gene carriers measured by nephelometry were very low. Peptide sequence analysis revealed that most of plasma transthyretin was normal with only a small amount of variant protein. This is the first report of a DNA deletion in the transthyretin gene. We speculate that the loss of valine in the carboxyl terminal region of the transthyretin monomer alters stability of the tetrameric protein, which leads to rapid clearance from the plasma and amyloid deposition in the tissue.

Asp187Asn mutation of gelsolin in an American kindred with familial amyloidosis, Finnish type (FAP IV)

Familial amloidosis, Finnish type (FAP IV) was identified clinically in an American kindred with Scandinavian ancestry. A polymerase chain reaction (PCR)-based DNA diagnostic assay was used to identify a G-to-A mutation at position 654 of the gelsolin cDNA (G654A) in this family. Molecular diagnostic testing demonstrated the mutation in individuals in three generations — the clinically affected proband, her deceased clinically affected father, and her presumably affected presymptomatic child. This report represents a rare example of FAP IV and the G654A mutation identified in a family outside Finland. The disease-associated haplotype was similar to that observed in Finnish FAP IV families (suggesting common distant ancestry).

Fibrinogen Aa Chain Leu 554: an African-American kindred with late onset renal amyloidosis

An African-American kindred with renal amyloidosis is described. Four members in two generations developed nephropathy in the sixth to eighth decade of life. Kidney biopsy and subcutaneous fat aspirate biopsy of one patient revealed amyloid deposits. DNA analysis showed that patients were heterozygous for a mutation in the fibrinogen A alpha chain gene with a guanine to thymine transversion at the second base of codon 554, predicting a leucine for arginine substitution. Peptide sequence analysis of isolated plasma fibrinogen showed normal peptide as well as variant peptide with leucine replacing arginine at position 554, as predicted by the DNA sequence. The ratio between normal and variant peptides was approximately 1:1 in one patient and 3:2 in another. Although this African-American kindred has the exact same mutation as a previously described Peruvian-Mexican kindred, the onset age in this kindred is much later than in the Peruvian-Mexican kindred. This finding may indicate the existence of additional factor(s) beside the primary causative genetic mutation, which affect the expression of the disease.

Amyloid polyneuropathy in two German-American families: a new transthyretin variant (Val 107).

We report studies on two German-American persons with systemic amyloidosis. Affected subjects presented with carpal tunnel syndrome in the sixth decade of life followed by peripheral neuropathy. DNA analysis of the transthyretin gene showed a new point mutation which is responsible for substitution of valine for isoleucine at position 107 of the transthyretin molecule.

A new transthyretin variant (Ser 24) associated with familial amyloid polyneuropathy.

An American kindred with systemic amyloidosis presenting with carpal tunnel syndrome, peripheral neuropathy, and cardiomyopathy is reported. The transthyretin gene of a patient was analysed by direct DNA sequencing and both cytosine and thymine were present at the first base of codon 24. This new point mutation in exon 2 results in the amino acid substitution of serine for proline in the A-B loop of the transthyretin molecule. DNA testing for this mutant allele by restriction fragment length polymorphism analysis based on the polymerase chain reaction is described.

Transthyretin mutation (serine 84) associated with familial amyloid polyneuropathy in a Hungarian family.

A Hungarian family with familial amyloid polyneuropathy (FAP) was studied. The disease presented in two individuals with carpal tunnel syndrome in the fourth and fifth decades of life. The proband subsequently developed vitreous opacities requiring vitrectomy and now has evidence of cardiomyopathy. Single strand conformation polymorphism analysis and direct DNA sequencing revealed a variant AGC (serine) codon at amino acid position 84 of the amyloid precursor protein, transthyretin (TTR). The same single amino acid substitution in TTR was detected in an Indiana kindred with Swiss/German origin. Six individuals of the 11 tested being at risk for FAP proved to have the mutation in the present Hungarian kindred. This is the first description of this TTR gene mutation in Europe. Despite TTR gene haplotype analysis which suggests that the Hungarian and Indiana kindreds may have a common origin, no genealogical link has been identified between the families living in Indiana and Hungary.

Haplotype analysis of the transthyretin gene: Evidence for multiple recurrence of the Met30 mutation in the Caucasian population

Familial amyloidotic polyneuropathy occurs most often as a result of mutations within the transthyretin (TTR) gene. Several of these mutations have been identified in multiple kindreds from different geographic and ethnic origins. In the present paper, we report a new haplotype analysis procedure based on polymerase chain reaction induced mutation restriction analysis (PCR-IMRA). This procedure, which is capable of distinguishing polymorphisms at six sites within the TTR gene, was used to compare the haplotypes of several independent Caucasian kindreds manifesting the Mct30, Ala60, and Ser84 TTR variants, as well as to demonstrate the utility of the new PCR-IMRA procedure for the study of TTR related hereditary amyloidosis. Our results suggest that the Met30 TTR variant has been caused by multiple mutational events in the Caucasian population. However, haplotypes were identical for Ser84 kindreds in the USA and Hungary, and for Ala60 kindreds in the USA and Australia, which may suggest common origins for ...

Identification of a novel non-amyloidogenic transthyretin polymorphism (His 74) in the German population

We examined the transthyretin gene of a German individual by direct DNA sequencing and found a guanine to cytosine transversion at the first base ofcodon 74 which resulted in a replacement ofhistidinefor aspartic acid. This mutation was confirmed by restriction fragment length polymorphism analysis using the polymerase chain reaction and the variant protein was proven to exist in plasma by sequence analysis of purified transthyretin. This variant transthyretin which was found in 7 of 4000 individuals by isoelectric focusing gel analysis is considered to be a relatively common polymorphism in the German population. None of the 7 individuals has a family history of amyloidosis or thyroid disorder.