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1.
A novel SERPINC1 frameshift mutation in two antithrombin deficiency families.
Zhang, D, Sun, B, Zhang, X, Li, H, Lin, Y, Qin, L, Chen, L, Zhang, L, Ru, K, Yang, R
International journal of laboratory hematology. 2020;(2):e48-e51
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2.
A Case Report of Primary Neonatal Hypocholinesterase Caused by Homozygous Frameshift Mutation of the utyrylcholinesterase (BCHE) Gene and Review of Literature.
Lv, HY, Yang, LH, Bu, LN, Wang, QL, Gu, XL, Wang, ZY, Ren, PS, Li, LX
Clinical laboratory. 2019;(7)
Abstract
BACKGROUND Primary neonatal hypocholinesterase is rare; its genetic pattern and mutation still need to be further studied. METHODS The patient and his parents are studied using next-generation sequencing technology. RESULTS A boy one day after birth is admitted to the Neonatal Intensive Care Unit at our hospital after experiencing intermittent vomiting for 12 hours. The patient's serum cholinesterase level (113 - 283 U/L) is lower than normal value (4,000 - 12,600 U/L). Many factors of low serum cholinesterase are excluded. We highly suspect that it may be related to congenital factors. Molecular genetic test results show that the patient carried the BCHE gene (NM_000055.2) and has homozygous frameshift mutations at exon 2 c.401dupA (p.Asn134fs) of chromosome 3q26. It is a pathogenicity mutation. This locus mutation belongs to a novel pathogenic mutation. As a result of this mutation, the 134th amino acid Asn began to frameshift and the translation is terminated early. It can cause the Encoding of protein to truncate and lose its normal function. His parents' serum cholinesterase levels (father: 5,135 U/L; mother: 4,367 U/L) are in the normal value range, but his parents carried a heterozygous BCHE gene. CONCLUSIONS This study suggests that gene sequence detection should be carried out early in hypocholinesterase of nknown cause in neonates. This study can not only improve understanding of the etiology and pathological mechanism of hypocholinesterase, but also it can enlarge the hypocholinesterase gene mutation spectrum.
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3.
Phenotype-genotype correlation with Sanger sequencing identified retinol dehydrogenase 12 (RDH12) compound heterozygous variants in a Chinese family with Leber congenital amaurosis.
Li, Y, Pan, Q, Gu, YS
Journal of Zhejiang University. Science. B. 2017;(5):421-429
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Abstract
BACKGROUND Leber congenital amaurosis (LCA) is a group of clinically and genetically heterogeneous retinal dystrophy. To date, 22 genes are known to be responsible for LCA, and some specific phenotypic features could provide significant prognostic information for a potential genetic etiology. This study is to identify gene variants responsible for LCA in a Chinese family using direct Sanger sequencing, with the help of phenotype-genotype correlations. METHODS A Chinese family with six members including two individuals affected with LCA was studied. All patients underwent a complete ophthalmic examination. Based on phenotype-genotype correlation, direct Sanger sequencing was performed to identify the candidate gene on all family members and normal controls. Targeted next-generation sequencing was used to exclude other known LCA genes. RESULTS By Sanger sequencing, we identified two novel missense variants in the retinol dehydrogenase 12 (RDH12) gene: a c.164C>A transversion predicting a p.T55K substitution, and a c.535C>G transversion predicting a p.H179D substitution. The two affected subjects carried both RDH12 variants, while their parents and offspring carried only one of heterozygous variants, showing complete cosegregation of the variants. The compound heterozygous variants were not present in 600 normal controls. Besides, the RDH12 variants were confirmed by targeted next-generation sequencing. CONCLUSIONS The RDH12 compound heterozygous variants might be the cause of the LCA family. Our study adds to the molecular spectrum of RDH12-related retinopathy and offers an effective example of the power of phenotype-genotype correlations in molecular diagnosis of LCA.
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Next-generation sequencing confirms the implication of SLC24A1 in autosomal-recessive congenital stationary night blindness.
Neuillé, M, Malaichamy, S, Vadalà, M, Michiels, C, Condroyer, C, Sachidanandam, R, Srilekha, S, Arokiasamy, T, Letexier, M, Démontant, V, et al
Clinical genetics. 2016;(6):690-9
Abstract
Congenital stationary night blindness (CSNB) is a clinically and genetically heterogeneous retinal disorder which represents rod photoreceptor dysfunction or signal transmission defect from photoreceptors to adjacent bipolar cells. Patients displaying photoreceptor dysfunction show a Riggs-electroretinogram (ERG) while patients with a signal transmission defect show a Schubert-Bornschein ERG. The latter group is subdivided into complete or incomplete (ic) CSNB. Only few CSNB cases with Riggs-ERG and only one family with a disease-causing variant in SLC24A1 have been reported. Whole-exome sequencing (WES) in a previously diagnosed icCSNB patient identified a homozygous nonsense variant in SLC24A1. Indeed, re-investigation of the clinical data corrected the diagnosis to Riggs-form of CSNB. Targeted next-generation sequencing (NGS) identified compound heterozygous deletions and a homozygous missense variant in SLC24A1 in two other patients, respectively. ERG abnormalities varied in these three cases but all patients had normal visual acuity, no myopia or nystagmus, unlike in Schubert-Bornschein-type of CSNB. This confirms that SLC24A1 defects lead to CSNB and outlines phenotype/genotype correlations in CSNB subtypes. In case of unclear clinical characteristics, NGS techniques are helpful to clarify the diagnosis.
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[Genotype-phenotype correlation in patients with PRPH2-mutations].
Maertz, J, Gloeckle, N, Nentwich, MM, Rudolph, G
Klinische Monatsblatter fur Augenheilkunde. 2015;(3):266-74
Abstract
BACKGROUND The peripherin-2 (PRPH2) gene encodes a photoreceptor-specific transmembrane-protein called peripherin-2 which is critical for the formation and maintenance of rod and cone outer segments. Over 90 different disease-causing mutations in PRPH2 have been identified which cause a variety of forms of macular degeneration and also retinopathia pigmentosa. PATIENTS/MATERIAL AND METHODS This study is a retrospective observational study of 3 patients ascertained over a 5 month period in the ophthalmogenetic consultation of the university ophthalmic clinic. So far, the patients were followed for 8 months at least. Data examined included clinical history, pedigree analysis, ophthalmological examination, fundus photography, autofluorescence imaging, optical coherence tomography, Arden colour test, Goldmann perimetry and detailed electrophysiological assessment. Blood samples were taken for DNA extraction and mutation analysis of PRPH2 and ABCA4, BEST1, C1QTNF5, CDH3, CNGB3, ELOVL4, FSCN2, PROM1, RDH12, RP1L1, RPGR, TIMP3 was performed. RESULTS All patients had presented with clinically evident maculopathy and visual acuities in the range of 1/50 Metervisus to 0.8 p [dec.]. All had specific electroretinogrammes. All PRPH2 mutations were autosomal dominant. One family was heterozygous for a previously reported missense mutation in the PRPH2 gene c.514C>T, p.R172W. The other patient was heterozygous for a so far non-described PRPH2 deletion and frameshift mutation c.74_77delGGTT, p.W25SfsX12 leading most likely to a truncated, dysfunctional protein. All patients showed a significant, inter-individual phenotypical variability. CONCLUSION The data add to the documented phenotypical variability of PRPH2 mutations and describe the c.74_77delGGTT, p.W25SfsX12 mutation within PRPH2 for the first time. FAF, OCT and electrophysiological exams are helpful tools for diagnosis and evaluation of macular disease due to PRPH2 mutations.
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Cone-rod dystrophy caused by a novel homozygous RPE65 mutation in Leber congenital amaurosis.
Jakobsson, C, Othman, IS, Munier, FL, Schorderet, DF, Abouzeid, H
Klinische Monatsblatter fur Augenheilkunde. 2014;(4):405-10
Abstract
BACKGROUND The aim of this study was to describe an unexpected phenotype in a family with Leber congenital amaurosis (LCA) due to a retinal pigment epithelium-specific protein 65 kDa (RPE65) homozygous mutation. HISTORY AND SIGNS We analyzed a family from Yemen in which 3 individuals were affected with LCA. Linkage analysis using markers flanking the known LCA genes was done, followed by direct sequencing of RPE65. THERAPY AND OUTCOME Severe visual impairment and night blindness were observed during infancy. We observed photophobia only in the 8-year-old patient. The youngest affected had bilateral hyperopia of +3.50 and visual acuity of 1/60. The oldest two had visual acuity limited to hand movements in the right eye (OD) and counting fingers in the left eye (OS) for the oldest and of 5/60 OD, 6/60 OS for the other. They showed disc pallor, attenuated vessels, white flecks in the retina mid-periphery and bull's eye maculopathy. ERGs of the oldest child were completely unresponsive. Genomic sequencing identified a novel homozygous missense mutation, IVS2-3C>G, in the second RPE65 intron. CONCLUSIONS We identified a novel LCA-related homozygous RPE65 mutation associated with a severe clinical presentation including an early and severe cone dysfunction. This is in contrast with the presentation associated with other RPE65 mutations predominantly causing rod-cone dystrophy with residual visual function.
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Adults with a history of possible Dravet syndrome: an illustration of the importance of analysis of the SCN1A gene.
Verbeek, NE, van Kempen, M, Gunning, WB, Renier, WO, Westland, B, Lindhout, D, Brilstra, EH
Epilepsia. 2011;(4):e23-5
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Abstract
Most patients with Dravet syndrome have de novo mutations in the neuronal voltage-gated sodium channel type 1 (SCN1A) gene. We report on two unrelated fathers with severe childhood epilepsy compatible with a possible diagnosis of Dravet syndrome, who both have a child with Dravet syndrome. Analysis of the SCN1A gene revealed a pathogenic mutation in both children. One father exhibited somatic mosaicism for the mutation detected in his son. A relatively favorable cognitive outcome in patients with Dravet syndrome patients may be explained by somatic mosaicism for the SCN1A mutation in brain tissue. A mild form of Dravet syndrome in adult patients is associated with a high recurrence risk and possibly a more severe epilepsy phenotype in their offspring.
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Acrodermatitis enteropathica: an uncommon differential diagnosis in childhood - first description of a new sequence variant.
Jung, AG, Mathony, UA, Behre, B, Küry, S, Schmitt, S, Zouboulis, CC, Lippert, U
Journal der Deutschen Dermatologischen Gesellschaft = Journal of the German Society of Dermatology : JDDG. 2011;(12):999-1002
Abstract
An 11-month-old boy was brought to our clinic with superinfected, sharply-defined, symmetrical, erythematous macules and vesicles, some with yellowish-brownish crusts, on the cheeks, fingers, and in the diaper region. The suspected impetigo contagiosa had failed to respond to both topical antiseptic therapy and systemic antibiotics. Because of the unusual clinical picture and course, we measured the serum zinc level. A significantly reduced level of 2 μmol/l (normal range 9.2-18.4 μmol/l) was identified. Initial skin lesions had appeared one week after weaning (5th week after birth). Since the age of 8 months the infant had also had recurrent diarrhea. Two weeks after zinc-histidine substitution, the diarrhea ceased and skin lesions slowly disappeared. Molecular genetic testing for the SLC39A4 (zinc transporter) gene revealed compound heterozygosity for the previously unidentified mutations c.1465_1474+4del (p.?) and c.295G>A (p.Ala99Thr). The parents are healthy heterozygous gene carriers. The same compound heterozygosity was later detected in the newborn brother of our patient shortly after birth. A zinc deficiency could therefore be identified and treated before symptoms occurred. The inherited autosomal recessive zinc transporter deficiency is termed acrodermatitis enteropathica. Lifelong zinc substitution is recommended. A differential diagnosis can be difficult because bacterial and fungal superinfection is common in zinc deficiency. Precise diagnosis requires testing family members for the gene.
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Mutations in PEX10 are a cause of autosomal recessive ataxia.
Régal, L, Ebberink, MS, Goemans, N, Wanders, RJ, De Meirleir, L, Jaeken, J, Schrooten, M, Van Coster, R, Waterham, HR
Annals of neurology. 2010;(2):259-63
Abstract
Peroxisomal biogenesis disorders typically cause severe multisystem disease and early death. We describe a child and an adult of normal intelligence with progressive ataxia, axonal motor neuropathy, and decreased vibration sense. Both patients had marked cerebellar atrophy. Peroxisomal studies revealed a peroxisomal biogenesis disorder. Two mutations in PEX10 were found in the child, c.992G>A (novel) and c.764_765insA, and in the adult, c.2T>C (novel) and c.790C>T. Transfection with wild-type PEX10 corrected the fibroblast phenotype. Bile acid supplements and dietary restriction of phytanic acid were started. Peroxisomal biogenesis disorders should be considered in the differential diagnosis of autosomal recessive ataxia.
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Sphingolipid activator protein B deficiency: report of 9 Saudi patients and review of the literature.
Al-Hassnan, ZN, Al Dhalaan, H, Patay, Z, Faqeih, E, Al-Owain, M, Al-Duraihem, A, Faiyaz-Ul-Haque, M
Journal of child neurology. 2009;(12):1513-9
Abstract
Mutated PSAP gene resulting in sphingolipid activator protein B deficiency is known to cause metachromatic leukodystrophy variant in which arylsulfatase A is normal. Of 16 patients with metachromatic leukodystrophy that were evaluated in our center, 7 patients were diagnosed with arylsulfatase A-deficient metachromatic leukodystrophy, whereas 9 children from 4 unrelated Saudi families were found to have sphingolipid activator protein B deficiency. PSAP analysis found that the 4 families segregate the same homozygous mutation that was a g.722G>C transversion resulting in C241S change, which was previously reported in an Arab patient. Our work, which reports the largest series of patients with sphingolipid activator protein B deficiency, suggests that this variant is likely to be more common than arylsulfatase A-deficient metachromatic leukodystrophy in Arabs, a notion that has potential diagnostic and preventive implications.