Laryngeal presentation of systemic apolipoprotein A-I-derived amyloidosis

The APOA1 p.Leu202Arg variant potentially causes autosomal recessive cardiac amyloidosis

ApoA-I amyloidosis is an extremely rare form of systemic amyloidosis that commonly involves the heart, kidneys, and liver. ApoA-I amyloidosis is caused by amyloidogenic variants of APOA1 that are inherited in an autosomal dominant manner. Here, we report a 69-year-old man with sporadic cardiac amyloidosis who was born to consanguineous parents and carried a homozygous variant of p.Leu202Arg in APOA1.

Echocardiographic findings in subjects with an amyloidogenic apolipoprotein A1 pathogenic variant

BACKGROUND

Very small case series of patients with apolipoprotein A1 (ApoA1) amyloidosis are available.

METHODS

We described the clinical and echocardiographic characteristics of individuals with the pathogenic APOA1 variant Leu75Pro (p. Leu99Pro), referred for cardiac screening.

RESULTS

We enrolled 189 subjects, 54% men, median age 55 years (interquartile range 42-67), 39% with concomitant renal disease and 31% with liver disease. Median left ventricular ejection fraction was 60% (55-66). Overall, these subjects did not show overt diastolic dysfunction nor left ventricular (LV) hypertrophy. Age correlated with interventricular septal (IVS) thickness (r = 0.484), LV mass index (r = 0.459), E/e' (r = 0.501), and right ventricular free wall thickness (r = 0.594) (all p < 0.001). Some individuals displayed red flags for cardiac amyloidosis (CA), and 14% met non-invasive criteria for CA. Twenty-nine subjects died over 5.8 years (4.1-8.0), with 10 deaths for cardiovascular causes. Individuals meeting echocardiographic criteria for CA had a much higher risk of all-cause death (p = 0.009), cardiovascular death (p = 0.001), cardiovascular death or heart failure (HF) hospitalisation (p < 0.001). Subjects with both renal and liver involvement had a more prominent cardiac involvement, and shortest survival.

CONCLUSIONS

Subjects with the APOA1 Leu75Pro variant displayed minor echocardiographic signs of cardiac involvement, but 14% met echocardiographic criteria for CA. Subjects with suspected CA had a worse outcome.

Molecular simulation unravels the amyloidogenic misfolding of nascent ApoA1 protein, driven by deleterious point mutations occurring in between 170-178 hotspot region

Protein ApoA1 is extensively studied for its role in lipid metabolism. Its seedy dark side of amyloid formulation remains relatively understudied yet. Due to genetic mutations, the protein pathologically misshapes into its amyloid form that gets accumulated in various organs, including the heart. To contrive effective therapeutics against this debilitating congenital disorder, it is imperative to comprehend the structural ramifications induced by mutations in APoA1's dynamic conformation. Till now, several point mutations have been implicated in ApoA1's amyloidosis, although only a handful has been examined considerably. Especially, the single nucleotide polymorphisms (SNPs) that occur in-between 170-178 mutation hotspot site of APoA1 needs to be investigated, since most of them are culpable of amyloid deposition in the heart. To that effect, in the present study, we have computationally quantified and studied the ApoA1's biomolecular modifications fostered by SNPs in the 170-178 mutation hotspot. Findings from discrete molecular dynamics simulation studies indicate that the SNPs have noticeably steered the ApoA1's behaviour from its native structural dynamics. Analysis of protein's secondary structural changes exhibits a considerable change upon mutations. Further, subjecting the protein structures to simulated thermal denaturation shows increased resistance to denaturation among mutants when compared to native. Further, normal mode analysis of protein's dynamic motion also shows discrepancy in its dynamic structural change upon SNP. These structural digressions induced by SNPs can very well be the biomolecular incendiary that drives ApoA1 into its amyloidogenesis. And, understanding these structural modifications initiates a better understanding of SNP's amyloidogenic pathology on APoA1.Communicated by Ramaswamy H. Sarma.

The experience of hereditary apolipoprotein A-I amyloidosis at the UK National Amyloidosis Centre

INTRODUCTION

Hereditary apolipoprotein A-I (AApoAI) amyloidosis is a rare heterogeneous disease with variable age of onset and organ involvement. There are few series detailing the natural history and outcomes of solid organ transplantation across a range of causative APOA1 gene mutations.

METHODS

We identified all patients with AApoAI amyloidosis who presented to the National Amyloidosis Centre (NAC) between 1986 and 2019.

RESULTS

In total, 57 patients with 14 different APOA1 mutations were identified including 18 patients who underwent renal transplantation (5 combined liver-kidney (LKT) and 2 combined heart-kidney (HKT) transplants). Median age of presentation was 43 years and median time from presentation to referral was 3 (0-31 years). Involvement of the kidneys, liver and heart by amyloid was detected in 81%, 67% and 28% of patients, respectively. Renal amyloidosis was universal in association with the most commonly identified variant (Gly26Arg, n = 28). Across all variants, patients with renal amyloidosis had a median creatinine of 159 µmol/L and median urinary protein of 0.3 g/24 h at the time of diagnosis of AApoAI amyloidosis and median time from diagnosis to end-stage renal disease was 15.0 (95% CI: 10.0-20.0) years. Post-renal transplantation, median allograft survival was 22.0 (13.0-31.0) years. There was one early death following transplantation (infection-related at 2 months post-renal transplant) and no episodes of early rejection leading to graft failure. Liver transplantation led to regression of amyloid in all four cases in whom serial 123I-SAP scintigraphy was performed.

CONCLUSIONS

AApoAI amyloidosis is a slowly progressive disease that is challenging to diagnose. The outcomes of transplantation are encouraging and graft survival is excellent.

Localised laryngotracheal amyloidosis: a differential diagnosis not to forget

We present a case of multifocal laryngotracheal amyloidosis (LTA) in a 43-year-old man with persistent and progressive dysphonia and dyspnoea, and a first inconclusive histology. Although laryngeal amyloidosis accounts for fewer than 1% of all benign laryngeal tumours, it is in fact the most common site of amyloid deposition in the head, neck and respiratory tract. The clinical scenario is non-specific and diagnosis depends on a high degree of suspicion and on histology. Imaging is useful in mapping lesions, which are often more extensive than they appear during laryngoscopy. Despite being a benign entity, the prognosis is variable with a high-rate and long-latency recurrences, requiring long-term follow-up.

One Hundred Cases of Localized Laryngeal Amyloidosis - Evidence for Future Management

OBJECTIVE/HYPOTHESIS

To update the current understanding of localized laryngeal amyloidosis by analyzing the NHS National Amyloidosis Database and to further clarify the important ongoing management issues.

STUDY DESIGN

Retrospective review, case series.

METHODS

Patients with laryngeal amyloid were identified from the database of the NHS National Amyloidosis Center, UCL, Royal Free Hospital, London between 2000 and 2017. Patient demographics and disease profile were collated, including the exact location of amyloid deposit, treatments if any, and progression of disease.

RESULTS

One hundred and three patients with localized laryngeal amyloid where identified from the database, with a mean age of 54 at diagnosis and female to male ratio of 54:49. Three patients were excluded from further analysis due to limited database information. The majority of amyloid was found in either the supraglottis (44) or glottis (53) but all the laryngeal subsites were involved. One-third of the patients (34) had amyloid in more than one laryngeal subsite. No patients were found to progress to systemic amyloid, but many progressed locally to other subsites or further down the LTB tree (29%). Three patients were successfully treated with radiotherapy after other modalities had failed.

CONCLUSIONS

This is the largest case series reported to date of localized laryngeal amyloidosis. It highlights the high incidence of multifocal disease and the significant proportion of patients who progressed, not to systemic amyloidosis but to more extensive localized amyloid. We recommend that in all cases of laryngeal amyloid, patients should undergo a thorough assessment of the upper and lower airways and have ongoing surveillance for at least 15 years.

LEVEL OF EVIDENCE

4 Laryngoscope, 131:E1912-E1917, 2021.

Long-term Follow-up After Radiation Therapy for Laryngeal Amyloidosis

OBJECTIVES

Laryngeal amyloidosis (LA) is a rare disease characterized by extracellular protein deposition within the larynx. Treatment is difficult due to the frequently submucosal and multifocal nature of disease. The mainstay of treatment is surgical resection; however, recurrence rates are high. Recently, use of radiotherapy (RT), either alone or postoperatively, for LA has been adapted from the management of extramedullary plasmacytoma and has been shown to provide local disease control. Here, we describe the experience with adjuvant RT for LA at our center.

STUDY DESIGN

Retrospective case series.

METHODS

Retrospective study of patients with amyloidosis of the larynx, with or without other disease sites, seen at a tertiary academic center between 2011 and 2019. Outcomes included disease characteristics, recurrence rates, treatment modalities, and pre- and posttreatment voice handicap index (VHI)-10.

RESULTS

Ten patients met eligibility criteria. Mean follow-up time for all patients was 62.0 ± 41.0 months; mean follow-up time after last treatment was 51 ± 55 months. All but one patient underwent surgical resection of disease. Seven patients underwent subsequent RT. Of these seven, six underwent RT at our institution; five received a dose of 45 Gray (Gy); and one received a dose of 20 Gy. All seven completed RT without toxicity-related interruption. Patients undergoing RT underwent 2.1 ± 1.3 surgical procedures prior to RT; no patients required surgery after RT. Mean pretreatment VHI-10 was 22.9 ± 8.1; mean posttreatment VHI-10 was 12.9 ± 13.3.

CONCLUSION

RT after surgery for LA can provide good local control without unacceptable toxicity and may decrease the need for further surgery.

LEVEL OF EVIDENCE

4 Laryngoscope, 131:1810-1815, 2021.

Multifocal head and neck amyloidosis as a diagnostic clue of systemic lupus erythematosus (SLE): A case report

RATIONALE

Amyloidosis accounts for 2% of head and neck tumors. Amyloidosis that develops in the head and neck region is localized amyloidosis. Multifocal amyloidosis in the head and neck region is extremely rare.

PATIENT CONCERNS

The patient presented to the clinic of otolaryngology with nasal obstruction, anosmia and left neck mass for several months.

DIAGNOSIS

A left nasopharynx tumor was revealed under nasopharyngeal scope. Eosinophilic, proteinaceous material was revealed under a pathology scope in the nasopharynx tissue and neck tumor. Congo red staining demonstrated pale congophilic amorphous material with apple-green birefringence under cross-polarized light, and multifocal amyloidosis was diagnosed. Amyloidosis secondary to systemic lupus erythematosus (SLE) was confirmed after a series of investigations.

INTERVENTIONS

The patient underwent local excision for multifocal amyloidosis without following management. To control underlying SLE, the patient accepted steroid pulse therapy and immunosuppressants. The patient eventually achieved disease remission.

OUTCOMES

During the 6 months of follow-up in the outpatient department of otolaryngology and rheumatology, complications, recurrence of nasopharyngeal amyloidosis, and SLE flare-up were not observed.

LESSONS

Head and neck amyloidosis involving the nasopharynx is a rare presentation of this disease. Head and neck multifocal amyloidosis should be taken as a hint of systemic disease. In head and neck amyloidosis, a comprehensive survey should be performed to clarify the underlying disease predisposing to amyloidosis and organ involvement.

CO2 laser supraglottic resurfacing for non-granulomatous chronic supraglottitis in two children

Chronic epiglottitis and supraglottitis are clinical entities that present with respiratory distress and are primarily associated with autoimmune disorders, gastroesophageal reflux disease, or angioedema. First described in adults with sarcoidosis in 2010, CO2 laser epiglottis resurfacing has been effective in reducing epiglottic edema. We present two cases of adolescent males with non-granulomatous chronic supraglottitis who were successfully treated with CO2 laser supraglottic resurfacing.

Genetics of Coronary Artery Disease

Genetic factors contribute importantly to the risk of coronary artery disease (CAD), and in the past decade, there has been major progress in this area. The tools applied include genome-wide association studies encompassing >200,000 individuals complemented by bioinformatic approaches, including 1000 Genomes imputation, expression quantitative trait locus analyses, and interrogation of Encyclopedia of DNA Elements, Roadmap, and other data sets. close to 60 common SNPs (minor allele frequency>0.05) associated with CAD risk and reaching genome-wide significance (P<5 × 10(-8)) have been identified. Furthermore, a total of 202 independent signals in 109 loci have achieved a false discovery rate (q<0.05) and together explain 28% of the estimated heritability of CAD. These data have been used successfully to create genetic risk scores that can improve risk prediction beyond conventional risk factors and identify those individuals who will benefit most from statin therapy. Such information also has important applications in clinical medicine and drug discovery by using a Mendelian randomization approach to interrogate the causal nature of many factors found to associate with CAD risk in epidemiological studies. In contrast to genome-wide association studies, whole-exome sequencing has provided valuable information directly relevant to genes with known roles in plasma lipoprotein metabolism but has, thus far, failed to identify other rare coding variants linked to CAD. Overall, recent studies have led to a broader understanding of the genetic architecture of CAD and demonstrate that it largely derives from the cumulative effect of multiple common risk alleles individually of small effect size rather than rare variants with large effects on CAD risk. Despite this success, there has been limited progress in understanding the function of the novel loci; the majority of which are in noncoding regions of the genome.

Long-term follow-up after surgery in localized laryngeal amyloidosis

To study effectiveness of surgery and watchful waiting in localized laryngeal amyloidosis, retrospective case series. This retrospective study comprises all consecutive patients with localized laryngeal amyloidosis surgically treated in a tertiary hospital between 1994 and February 2016. Recurrence rate, revision surgery, progression to systemic amyloidosis, and changes in voice were monitored yearly. Eighteen patients were included. Seven women and eleven men had a median age 50 years (range 21-77 years) and median follow-up 6.4 years (2.4-17 years). Amyloid was located in subglottis (5), glottis (8), false vocal folds (8) and other supraglottic areas (5), in more than one laryngeal region (13) and bilaterally (12). Cold steel excision was used at the glottis; CO2 laser excision, sometimes assisted by microdebrider, at other laryngeal areas. Eleven patients needed revision surgery, ten within the first 4 years after surgical treatment. One patient needed his first revision surgery after 11 years. Five patients needed a second revision within 6 years after initial diagnosis. Two patients needed a third revision. Indications for first revision surgery were progression (8) with dysphonia (7), dyspnea (2), dysphagia (1), exclusion of malignancy (1), and aphonia (1). No patient developed systemic amyloidosis during follow-up. Although local progression of amyloid necessitates revision surgery once or twice in the first 4-6 years, progression slows down thereafter. Late progression, however, remains possible.

Chronic non-granulomatous supraglottitis: a rare and difficult disease

OBJECTIVES

To examine chronic non-granulomatous supraglottitis, a rare disorder of uncertain aetiology with few reported cases in the literature.

CASE REPORTS

We describe two cases of chronic non-granulomatous supraglottitis that led to persistent respiratory compromise. Patients underwent extensive investigation that failed to reveal a definitive diagnosis.

CONCLUSION

In patients suffering from chronic inflammation of the supraglottic larynx without evidence of infection, neoplasm or granulomatous disease, many disorders must be ruled out in order to diagnose chronic non-granulomatous supraglottitis, which is a diagnosis of exclusion. We review the literature on this rare entity, discuss current management strategies, and suggest an algorithm for diagnostic investigation.

The fibrillogenic L178H variant of apolipoprotein A-I forms helical fibrils

A number of amyloidogenic variants of apoA-I have been discovered but most have not been analyzed. Previously, we showed that the G26R mutation of apoA-I leads to increased β-strand structure, increased N-terminal protease susceptibility, and increased fibril formation after several days of incubation. In vivo, this and other variants mutated in the N-terminal domain (residues 26 to ∼90) lead to renal and hepatic accumulation. In contrast, several mutations identified within residues 170 to 178 lead to cardiac, laryngeal, and cutaneous protein deposition. Here, we describe the structural changes in the fibrillogenic variant L178H. Like G26R, the initial structure of the protein exhibits altered tertiary conformation relative to wild-type protein along with decreased stability and an altered lipid binding profile. However, in contrast to G26R, L178H undergoes an increase in helical structure upon incubation at 37°C with a half time (t_1/2) of about 12 days. Upon prolonged incubation, the L178H mutant forms fibrils of a diameter of 10 nm that ranges in length from 30 to 120 nm. These results show that apoA-I, known for its dynamic properties, has the ability to form multiple fibrillar conformations, which may play a role in the tissue-specific deposition of the individual variants.

Amyloidogenicity and clinical phenotype associated with five novel mutations in apolipoprotein A-I

The phenotype of hereditary apolipoprotein A-I amyloidosis is heterogeneous with some patients developing extensive visceral amyloid deposits and end-stage renal failure as young adults and others having only laryngeal and/or skin amyloid, which may be of little clinical consequence. Clinical management and prognosis of patients with systemic amyloidosis depend entirely on correct identification of the fibril protein, such that light chain amyloidosis (AL, previously referred to as "primary"), the most frequently diagnosed type, is treated with chemotherapy, which has absolutely no role in hereditary apolipoprotein A-I amyloidosis. We report five novel apolipoprotein A-I variants, four of which were amyloidogenic and one of which was incidental in a patient with systemic AL amyloidosis. Interestingly, only one of four patients with apolipoprotein A-I amyloidosis had a family history of similar disease. Laser microdissection and tandem mass spectrometry-based proteomics were used to confirm the amyloid fibril protein and, for the first time in apolipoprotein A-I amyloidosis, demonstrated that only mutated protein as opposed to wild-type apolipoprotein A-I was deposited as amyloid. The clinical spectrum and outcome of hereditary apolipoprotein A-I amyloidosis are reviewed in detail and support the need for sequencing of the apolipoprotein A-I gene among patients with apparent localized amyloidosis in whom IHC is nondiagnostic of the fibril protein, even in the absence of a family history of disease.