Genotype and Phenotype Spectrum ofFRMD7-Associated Infantile Nystagmus Syndrome
Jae‐Hwan ChoiJae Ho JungEun Hye OhJin‐Hong ShinHyang-Sook KimJe Hyun SeoSeo‐Young ChoiMin-Ji KimHee Young ChoiChangwook LeeKwang‐Dong Choi
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Purpose: We investigate the genotype and phenotype spectrum of FRMD7-associated infantile nystagmus syndrome in Korean probands. Methods: A total of 37 patients with infantile nystagmus syndrome were recruited prospectively for genetic analysis. We performed polymerase chain reaction (PCR)-based direct sequencing and haplotype analysis for FRMD7. Detailed ophthalmic examinations and eye movement recordings were compared between FRMD7 and non-FRMD7 groups. Results: In 13 (35%) of 37 patients, five different mutations of FRMD7 were detected: start codon mutation c.1A>G, splice site mutation c.162+6T>C, and three missense mutations (c.575A>C, c.722A>G, and c.875T>C). The latter mutation was identified in seven unrelated patients, and always was accompanied with two single nucleotide polymorphisms of exon 12 (rs6637934, rs5977623). Compared to non-FRMD7 groups, a cup-to-disc ratio was significantly decreased in FRMD7 groups (P < 0.001), and a disc–macula distance to disc diameter ratio markedly increased in the FRMD7 group (P = 0.015). Most patients in the FRMD7 group had at least two types of the nystagmus waveforms, and the most common type was unidirectional jerk nystagmus (75%), such as pure jerk and jerk with extended foveation, followed by pendular (25%), bidirectional jerk (19%), and dual jerk (6%) nystagmus. No significant differences were observed between FRMD7 and non-FRMD7 groups in terms of the nystagmus waveform, presence of periodic alternating nystagmus, and mean foveation time. Conclusions: We identified five FRMD7 mutations in 35% of our infantile nystagmus syndrome cohort, expanding its mutational spectrum. The missense mutation c.875T>C may be a common mutation arisen from the founder effect in Korea. Optic nerve dysplasia associated with FRMD7 mutations suggests that the abnormal development of afferent visual systems may affect neural circuitry within the oculomotor system.Keywords:
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Objective To identify the gene mutations of an inherited coagulation factor Ⅶ deficiency pedigree.Methods PCR and DNA sequencing were used to identify the FⅦ gene mutations in the proband.The identified mutations were validated by PCR followed by restriction fragment length polymorphism technique or DNA sequencing.100 healthy volunteers were chosen randomly as controls. Results R1S2Q and IVS6+1G→T double heterozygous mutations were discovered in the Droband.The pedigree analysis showed that R152Q missense mutation inherited from his father,and IVS6+1G→Twas from his mother. The R1S2Q missense mutation in exon 6 was not found in 100 healthy volunteers. Conclusion The congenital deficiency of F Ⅶ in the proband might be caused by the coinheritance of the R152Q missense mutation in exon 6 and the splicing donor site mutation ( ⅣS6+1G→T)in intron 6.
Key words:
Factor Ⅶ deficiency; Factor Ⅶ; Pedigree; Mutation; Polymerase chain reaction
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The objective of the study was to investigate a girl with giant axonal neuropathy and detect the mutation of GAN gene in her family. The encoding exons of GAN gene were amplified from genomic DNA of the proband and her parents by polymerase chain reaction and directly sequenced after purification. The proband manifested typical neurological symptoms and pathological abnormalities. The case had 2 heterozygous missense mutations in GAN gene: 1. c. 224 T>A in exon 2, her mother was a heterozygote of this mutation and had normal phenotype; 2. c.1634G>A in exon 10, and her father was a heterozygote of this mutation and had normal phenotype. Both of the mutations caused amino acid changes in the gigaxonin protein. In this family, missense mutation of c.224 T>A and missense mutation of c.1634G>A in GAN gene caused the phenotype of giant axonal neuropathy in the proband. Her parents are heterozygotes of the disease without symptoms.
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To discover the mutations of human blood coagulation factor V (FV) gene in a Chinese family with congenital factor V deficiency, and to explore the molecular mechanism associated with the congenital factor V deficiency.PCR and DNA sequencing were used to look for the FV gene mutations in the proband. And the novel mutation were testified by PCR restriction fragment length polymorphism technique or reverse DNA sequencing. One hundred healthy volunteers were chosen as controls at random.Two novel mutations were discovered in the FV gene of proband, which were the A1763C missense mutation in exon 11 and the splicing site mutation in the 3' terminal of intron 16 (G-->T). The pedigree analysis showed that the two mutations inherited from his parents respectively: the A1763C came from his father, and the G-->T from his mother. The A1763C missense mutation in exon 11 was not found in each of 100 healthy volunteers.The congenital deficiency of FV in the proband might be caused by the A1763C missense mutation in exon 11 and the splicing site mutation in the 3' terminal of intron 16, which jointly caused the proband to be a double heterozygote.
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Objective To identify SCN9A gene mutation in a family with severe primary erythermalgia.Methods Clinical data of family were collected and the encoding exons and their flanking sequences of SCN9A gene were amplified and sequenced from genomic DNA samples.Results A heterozygous c.1185C→G was found in exon 9 of the proband,which resulted in N395K amino acid substitution.The mutation was not detected in the proband's healthy mother or 50 unrelated healthy controls.Conclusion The missense mutation of SCN9A gene is the underlying cause of the patient's clinical phenotype.
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To search for mutations in NOTCH3 gene in four Chinese families with cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL).Four probands from four unrelated families with typical manifestations of CADASIL were studied. The 1 approximately 12 coding exons and their flanking intron sequences of NOTCH3 gene were amplified by PCR and sequenced. Some family members in the pedigree 2 and 4 were also examined for the NOTCH3 gene mutations.Four heterozygous missense mutations were identified in the four families: the proband 1 carrying a 268C-->T mutation in exon 3, the proband 2 a 322 C-->T mutation in exon 3, the proband 3 a 328 C-->T mutation inexon 3, and the proband 4 a 1819 C-->T mutation in exon 11, which resulted in the amino acid substitutions of R90C, C108R, R110C, and R607C respectively. Among them the C108R is a novel mutation not reported previously. Additionally, some members in the pedigree 2 and 4 also harbored the same mutations with the probands.Four heterozygous missense mutations in NOTCH3 gene have been found in four Chinese families with CADASIL. Different point mutations in NOTCH3 lead to similar phenotype of the disease. To search for mutations in NOTCH3 in related patients will help further understand and accurately diagnose the disease and perform prenatal diagnosis in CADASIL families.
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[Identification of a novel NF1 mutation in a Chinese family affected with neurofibromatosis type I].
To explore the molecular basis for a Chinese family affected with neurofibromatosis type I.Peripheral blood samples were collected from the proband and his parents. Potential mutations of NF1 gene were screened by PCR and Sanger sequencing. Pathogenicity of candidate mutations was analyzed using Polyphen-2 and Provean software.Two mutations of the NF1 gene, including c.702G>A (synonymous mutation) and c.1733T>G (missense mutation), were discovered in the proband. Neither mutation was found in his parents and 50 healthy controls. Bioinformatics analysis indicated that the c.1733T>G mutation (p.Leu578Arg) was probably damaging. The affected codon L578 is highly conserved across various species.The c.1733T>C mutation of the NF1 gene probably underlies the neurofibromatosis type I in this family.
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Objective To investigate 2 giant axonal neuropathy (GAN) families and detect the mutation of GAN gene in their family.Methods The encoding exons of GAN gene were amplified from genomic DNA of the probands and their parents by PCR and directly sequenced after getting purified.Results No.1 proband manifested typical neurological symptoms and pathological abnormalities.The case of the girl had 2 heterozygous missense mutations in GAN gene:1.c.224TA in exon 2,which results in the amino acid change of L75H;her mother was a heterozygote of this mutation and had normal phenotype,while her father had normal genotype in this site;2.c.1634GA in exon 10,her father was a heterozygote of this mutation and had normal phenotype,while her mother had normal genotype in this site.Both of the mutations cause amino acid changes in the gigaxonin protein.No mutation was detected in proband No.2.Conclusions In family 1,missense mutation of c.224TA and missense mutation of c.1634GA in GAN gene cause the phenotype of GAN in the proband.The girl′s parents are heterozygotes of the disease without symptoms.There may be other mode of inheritance in family 2.
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To search mutations in GLA gene in two Chinese families with classic Fabry disease.Two families with Fabry disease confirmed by pathological and clinical studies were reported here. In pedigree 1, 12 family members had paroxysmal pain on limb extremities. In pedigree 2, there were 8 patients and most of them had multi-organ involvement at the end stage of the disease. Two probands from the two families together with several of their family members were searched for mutations in GLA gene. After extraction of genomic DNA from peripheral leukocytes, all of the 7 exons and their flanking introns were amplified by PCR and directly sequenced.Both the proband 1 and proband 2 were identified to be hemizygotes of novel GLA missense mutations. G132T (TGG-->TGT) mutation in exon 1, resulting in the substitution of amino acid from tryptophan to cysteine (W44C), was detected in proband 1. G874C (GCT-->CCT) mutation in exon 6, resulting in the substitution of amino acid from alanine to praline (A292P), was detected in proband 2. Mothers of the 2 probands were heterozygotes carrying the same mutation as their sons.We report here 2 novel missense mutations in two Chinese families with classic Fabry disease. Different mutations in the same gene can result in phenotypes with significant deviation. Several female patients with the same clinical manifestations as male patients in the 2 families suggest that the X-linked dominant inheritance of the disease, possibly related to be the random X chromosome inactivation.
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To analyze genetic mutation and explore its molecular pathogenesis for an hereditary protein C (PC) deficient consanguineous pedigree.The pedigree included three generations and contained eight members. PC activity (PC:A), PC antigen (PC:Ag) and other coagulant parameters were detected for all family members. Protein C gene (PROC) include all the exons and intron exon boundaries were amplified by PCR for the proband, then analyzed by direct sequencing. Mutation sites were detected for the other family members.The PC:A and PC:Ag in the proband plasma were 20% (normal range 70% -140%) and 13.2% (normal range 70%-130%). A homozygous missense mutation g.6128T>G in exon 7 resulting in Phe139Val was identified in the proband. The PC:A and PC:Ag in her younger brother were 31% and 18.90%, Phe139Val homozygous was also found. The left family members were heterozygous for Phe139Val.Phe139Val homozygous missense mutation in exon 7 of PROC caused serious hereditary protein C deficiency. We speculated that homozygous mutation might be resulted from this consanguineous marriage.
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