Amyloid transthyretin (ATTR) amyloidosis with polyneuropathy (PN) is a progressive, debilitating, systemic disease wherein transthyretin protein misfolds to form amyloid, which is deposited in the endoneurium. ATTR amyloidosis with PN is the most serious hereditary polyneuropathy of adult onset. It arises from a hereditary mutation in the TTR gene and may involve the heart as well as other organs. It is critical to identify and diagnose the disease earlier because treatments are available to help slow the progression of neuropathy. Early diagnosis is complicated, however, because presentation may vary and family history is not always known. Symptoms may be mistakenly attributed to other diseases such as chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), idiopathic axonal polyneuropathy, lumbar spinal stenosis, and, more rarely, diabetic neuropathy and AL amyloidosis. In endemic countries (e.g., Portugal, Japan, Sweden, Brazil), ATTR amyloidosis with PN should be suspected in any patient who has length-dependent small-fiber PN with autonomic dysfunction and a family history of ATTR amyloidosis, unexplained weight loss, heart rhythm disorders, vitreous opacities, or renal abnormalities. In nonendemic countries, the disease may present as idiopathic rapidly progressive sensory motor axonal neuropathy or atypical CIDP with any of the above symptoms or with bilateral carpal tunnel syndrome, gait disorders, or cardiac hypertrophy. Diagnosis should include DNA testing, biopsy, and amyloid typing. Patients should be followed up every 6-12 months, depending on the severity of the disease and response to therapy. This review outlines detailed recommendations to improve the diagnosis of ATTR amyloidosis with PN.

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Expert consensus recommendations to improve diagnosis of ATTR amyloidosis with polyneuropathy

A majority of human genes contain non-coding intervening sequences – introns that must be precisely excised from the pre-mRNA molecule. This event requires the coordinated action of five major smal...

https://tandfonline.com/doi/pdf/10.1080/15476286.2016.1191735

Mutations in spliceosomal proteins and retina degeneration.

Purpose.
Retinitis pigmentosa (RP) is a highly heterogeneous genetic disease; therefore, an accurate molecular diagnosis is essential for appropriate disease treatment and family planning. The prevalence of RP in China had been reported at 1 in 3800, resulting in an estimated total of 340,000 Chinese RP patients. However, genetic studies of Chinese RP patients have been very limited. To date, no comprehensive molecular diagnosis has been done for Chinese RP patients. With the emergence of next-generation sequencing (NGS), comprehensive molecular diagnosis of RP is now within reach. The purpose of this study was to perform the first NGS-based comprehensive molecular diagnosis for Chinese RP patients.

Next-generation sequencing-based molecular diagnosis of a Chinese patient cohort with autosomal recessive retinitis pigmentosa.

Ocular Manifestations of Familial Transthyretin Amyloidosis

PURPOSE To identify disease-causing mutations and describe genotype-phenotype correlations in Thai patients with nonsyndromic retinitis pigmentosa (RP). METHODS Whole exome sequencing was performed in 20 unrelated patients. Eighty-six genes associated with RP, Leber congenital amaurosis, and cone-rod dystrophy were analyzed for variant detection. RESULTS Seventeen variants (13 novel and 4 known) in 13 genes were identified in 11 patients. These variants include 10 missense substitutions, 2 nonsense mutations, 3 deletions, 1 insertion, and 1 splice site change. Nine patients with identified inheritance patterns carried a total of 10 potentially pathogenic mutations located in genes CRB1, C8orf37, EYS, PROM1, RP2, and USH2A. Three of the nine patients also demonstrated additional heterozygous variants in genes ABCA4, GUCY2D, RD3, ROM1, and TULP1. In addition, two patients carried variants of uncertain significance in genes FSCN2 and NR2E3. The RP phenotypes of our patients were consistent with previous reports. CONCLUSIONS This is the first report of mutations in Thai RP patients. These findings are useful for genotype-phenotype comparisons among different ethnic groups.

Whole exome sequencing in Thai patients with retinitis pigmentosa reveals novel mutations in six genes.

The SNRNP200 gene encodes hBrr2, a helicase essential for pre-mRNA splicing. Six mutations in SNRNP200 have recently been discovered to be associated with autosomal dominant retinitis pigmentosa (adRP). In this work, we analyzed a Chinese family with adRP and identified a novel missense mutation in SNRNP200. To identify the genetic defect in this family, exome of the proband was captured and sequencing analysis was performed to exclude known genetic defects and find possible pathogenic mutations. Subsequently, candidate mutations were validated in affected family members using Sanger sequencing. A novel missense mutation, c.2653C>G transition (p.Q885E), in exon 20 of SNRNP200 was identified. The mutation co-segregated with the disease phenotype over four generations and was absent in 100 normal unaffected individuals. This mutation occurs at highly conserved position in hBrr2 and is predicted to have a functional impact, suggesting that hBrr2-dependent small nuclear riboproteins (snRNPs) unwinding and spliceosome activation is important in the pathogenesis of some variants of RP.

/pdf/a-novel-missense-snrnp200-mutation-associated-with-autosomal-r561rpd4tc.pdf

A Novel Missense SNRNP200 Mutation Associated with Autosomal Dominant Retinitis Pigmentosa in a Chinese Family

To describe the characteristic ophthalmic phenotypes of a large Chinese family with familial amyloid polyneuropathy due to a missense mutation in transthyretin (TTR) (c.307 C>G). Twenty-seven individuals (12 affected, 15 unaffected) from a five-generation Chinese family underwent general medical examination and comprehensive ophthalmic examination, including best correct visual acuity, intraocular pressure measurements, Schirmer test, slitlamp examination, fundoscopy, and ocular ultrasonography. Histological examination of vitreous biopsies using Congo red staining and immunohistochemistry was performed. Cardiovascular magnetic resonance (CMR), electrocardiogram, and echocardiogram were used to evaluate cardiac amyloidosis. Electromyography was used to evaluate nerve function. All four exons of TTR were amplified by PCR, sequenced using a Bigdye terminator v3.1 cycle sequencing kit and analyzed on an ABI 3700XL Genetic Analyzer. All 12 affected individuals in the family had ocular manifestations, including severe vitreous opacities, secondary glaucoma, xerophthalmia, dyscoria, and attenuated retinal arteries. Congo red staining demonstrated amyloid deposits in the vitreous, and immunohistochemical staining confirmed the deposition of TTR proteins in the vitreous. Twelve individuals had polyneuropathy, and electromyography detected functional damage in peripheral nerves. One individual was diagnosed with cardiac amyloidosis by CMR. Direct sequencing revealed the heterozygous missense mutation in TTR (c.307 C>G p.Gly83Arg) in all 12 affected individuals. The mutation co-segregated with the disease phenotype and was absent in 100 normal controls. Vitreous opacity is very common in patients with the TTR Gly83Arg mutation; other clinical characteristics associated with the mutation include polyneuropathy and cardiac amyloidosis.

/pdf/ophthalmic-manifestations-in-a-chinese-family-with-familial-1svk032kt0.pdf

Ophthalmic manifestations in a Chinese family with familial amyloid polyneuropathy due to a TTR Gly83Arg mutation

The invention relates to an isolated nucleic acid for coding an SNRNP200 mutant, an isolated polypeptide, a method, system and kit for screening a biological sample which is susceptible to the primary pigmentary degeneration of the retina and a method for screening a medicament for treating or preventing the primary pigmentary degeneration of the retina. Compared with the SEQ ID NO: 1, the sequence of the isolated nucleic acid for coding the SNRNP200 mutant has c. C2653G mutation. The susceptibility of the biological sample to the primary pigmentary degeneration of the retina can be detected effectively by detecting whether the new mutant exists in the biological sample.

Jin Xin

Papers

A Novel Missense SNRNP200 Mutation Associated with Autosomal Dominant Retinitis Pigmentosa in a Chinese Family

Ophthalmic manifestations in a Chinese family with familial amyloid polyneuropathy due to a TTR Gly83Arg mutation

SNRNP200 gene mutant and application thereof