A double heterozygote for (deltabeta)0-thalassemia and codons 41/42 (-TTCT) behaves as a homozygote for the frameshift mutation in a Chinese family

We present the case of a child in whom beta-thalassemia (thal) major was apparently caused by homozygosity for a 4-base deletion mutation [codons 41/42 (-TTCT)] of the beta-globin gene. However, the mutation was not identified in the father. The presence of a deletional beta-thal was detected by long-range polymerase chain reaction (PCR). We emphasize that the mutations found in the patient should always be confirmed to be present in both parents before molecular analysis is employed for clinical purposes.     

Clinical and hematologic features of beta0-thalassemia (frameshift 41/42 mutation) in Thai patients

BACKGROUND AND OBJECTIVES: Frameshift 41/42 mutation is the most common mutation of beta0-thalassemia found in Thailand. We studied clinical and hematologic features in 84 patients and relatives with frameshift 41/42 to determine whether it is possible to predict phenotypic severity from genetic factors. DESIGN AND METHODS: The clinical phenotypes and hematologic data of Thai patients with frameshift 41/42 were studied. Alpha-thalassemia, Hb Constant Spring (HbCS) genes and the presence of Xmnl-Ggamma polymorphism were studied in patients who had mild symptoms. RESULTS. Homozygotes for frameshift 41/42 and compound heterozygotes for frameshift 41/42 and beta0-thalassemia produced severe symptoms and have a thalassemia major phenotype. Combination of frameshift 41/42 and beta0-thalassemia or Hb E produced mild to moderate symptoms with thalassemia intermedia phenotype and severe symptoms with thalassemia major phenotype. The co-inheritance of beta-thalassemia or HbCS gene or the presence of Xmnl-Ggamma polymorphism was not associated with mild disease in patients with frameshift 41/42 and HbE. INTERPRETATION AND CONCLUSIONS: The clinical phenotype of homozygotes for frameshift 41/42 and compound heterozygotes for frameshift 41/42 and beta0-thalassemia could be used to predict a severe phenotype with thalassemia major. However, the clinical phenotype of compound heterozygotes of frameshift 41/42 and beta0-thalassemia or Hb E were variable and could not be accurately predicted. Associations between concomitant alpha-thalassemia or HbCS of the presence of Xmnl-Ggamma polymorphism and a mild clinical phenotype are not apparent, indicating the involvement of other ameliorating determinants or genetic modifications.     

A frameshift at codons 77/78 (-C): a novel beta-thalassemia mutation

We identified and characterized a novel beta-thalassemia (beta-thal) mutation due to a deletion of cytosine at codons 77/78 (-C) [CAC(His) CA- or CTG(Leu)--> -TG] found in a heterozygous state in four members of a Mexican family. The beta haplotype analysis performed on the family revealed that the frameshift at codons 77/78 (-C) mutation in this family is associated with haplotype V [- + - - - + ] and framework 2. Ten beta-thal alleles with a cytosine deletion are described at the Globin Gene Server, two of which are very near codon 77. The molecular pathology of beta-thal in the Mexican population has been shown to be heterogeneous, because some Mediterranean, Asian, private and rare alleles have been observed, a similar fact as has been observed in populations with a low frequency of beta-thal.     

The codons 8/9 (+G) mutation found for the first time in the Lebanese population

Thalassemia is a common inherited disease in the Mediterranean region. We here report a mutation new to the Lebanese population: the insertion of a G nucleotide at codons 8/9 [(+G) AAG-TCT (Lys-Ser) --> AAG-G-TCT (beta0)] of the beta-globin gene in a thalassemic patient with a mild phenotype. We discuss the possible factors that play a role in alleviating the severity of the disease in this case.     

A new frameshift beta zero-thalassemia mutation (codons 27-28 +C) found in a Chinese family.

A new beta zero-thalassemia mutation, a frameshift mutation with an insertion of a single cytosine nucleotide in codon 27-28, is described. The propositus, who is compound heterozygous for this mutation and the IVSII-654 C----T beta zero-thalassemia mutation, has the phenotype of severe beta-thalassemia major.     

beta-thalassemia intermedia caused by compound heterozygosity for Hb Malay (beta codon 19 AAC-->AGC; asn-->Ser) and codons 41/42 (-CTTT) beta(0)-thalassemia mutation

We report a case of beta-thalassemia intermedia caused by compound heterozygosity for hemoglobin (Hb) Malay and codon 41/42 (-CTTT) beta(0)-thalassemia mutation in a 38-year-old Chinese woman. This patient has long-standing anemia with a baseline Hb level of around 70 g/L. She worked as a full-time cashier and had not required regular blood transfusions. Nevertheless, she had splenomegaly necessitating splenectomy, cholelithiasis, and iron overload. This case illustrates the varied phenotypic expression associated with compound heterozygosity for Hb Malay and other beta-thalassemia mutations. Since Hb Malay migrates as Hb A on electrophoresis and chromatography, this variant Hb mutation ought to be included in the differential diagnosis for beta-thalassemia major or intermedia patients of Southeast Asian descent who are reported to have Hb A on the basis of Hb analysis. The possible presence of this mutation should also be considered in appropriate cases for genetic counseling in couples at risk of conceiving fetuses with beta-thalassemia major or intermedia.     

An insertional frameshift mutation of the beta-spectrin gene associated with elliptocytosis in spectrin nice (beta 220/216)

Spectrin Nice (beta 220/216) is a spectrin variant associated with a shortened beta chain found in a patient with elliptocytosis. The shortened beta chain (beta' chain) appeared as an additional band of approximately 216 Kd on sodium dodecyl sulfate-polyacrylamide gel electrophoresis and was defective in its ability to be phosphorylated. There were increased amounts of spectrin dimers in crude spectrin extracts from the propositus and the association constant of spectrin dimer self-association was decreased. There was an associated increase of the alpha I 74-Kd fragment from the alpha chain after partial trypic digestion of spectrin. To identify the underlying molecular defect, we analyzed cDNA for beta spectrin obtained by polymerase chain reaction amplification of reverse-transcribed reticulocyte messenger RNA from peripheral blood of the propositus. DNA sequencing of individual as well as pooled subclones showed that two extra bases (GA) are inserted in codon no. 2046 in one allele of the beta-spectrin gene. The insertion results in a frameshift mutation and generates an aberrant C-terminus truncated by about 4 Kd, consistent with the estimated size of the beta' chain observed. By allele-specific oligonucleotide hybridization, the insertion was shown to be present in the propositus and absent in his parents, confirming a previous proposal that it is a de novo mutation. The determination of the location of the mutation in spectrin Nice points to specific regions of the beta-spectrin chain where phosphorylation may occur. A model is proposed to describe the interaction between the alpha- and beta-spectrin chains and to explain the effects of the mutation found in spectrin Nice on the trypsin digestion pattern of its associated alpha chain.     

Origin of mutation in sporadic cases of haemophilia-B.

Abstract: Of the 45 haemophilia-B patients registered at the haemophilia centre in Malmo, Sweden, 24 are the sole members of their families to be affected, and in 13 of these 24 cases, ascendant relatives are available for study. Detection of the gene defect showed the mutation to be de novo in the proband in 3 of these 13 cases, and inherited from a carrier mother in the remaining 10 cases. All 10 carrier mothers were shown to have de novo mutations, as the patients' grandfathers were phenotypically and/or haematologically normal, and the grandmothers were non-carriers. Seven restriction fragment length polymorphisms (RFLPs) of the factor IX gene were used to determine whether the de izovo mutations of the 10 carrier mothers were of paternal or maternal origin. In 6/10 cases, the RFLP patterns were informative, and indicated the mutation to be of paternal origin.     

Origin of mutation in sporadic cases of haemophilia A

The aim of this study was to define the origin of mutation in sporadic cases of severe haemophilia A. The series was composed of 31 families with sporadic severe haemophilia A in the geographical catchment area of the Malmö haemophilia centre. The mutation was characterized in 29/31 families: inversion type 1 (n = 11), inversion type 2 (n = 3), other inversion (n = 1), small or partial deletion (n = 6), insertion (n = 2), non-sense mutation (n = 4) and mis-sense mutation (n = 2). Of 29 probands, eight carried a de novo mutation, whereas the proband's mother was found to carry the mutation in 21/29 families. Of the 21 carrier mothers, 16 had de novo mutations (i.e. the proband's maternal grandfather and grandmother were non-carriers). Owing to the lack of samples from the grandparents, origin could not be determined in the remaining five families. Polymorphisms of the FVIII gene were used to determine whether the de novo mutation of the carrier mother was of paternal or maternal origin. In 15/16 cases the mutation was of paternal origin and in 1/16 cases of maternal origin. In the series as a whole, mutation frequency was 6-fold higher in males than in females, but no differences in the ratio of sex-specific mutations rates was found among different types of mutation.     

Phaeohyphomycotic cyst: a clinicopathologic study of the first four cases described from Brazil

Four cases of phaeohyphomycosis in the form of chronic and isolated cysts are presented. The cysts were strictly confined to the subcutaneous tissue, with no involvement of the corresponding skin. Patients were asymptomatic, without satellite lesions or regional lymphadenopathy. The clinicopathologic importance of this type of phaeohyphomycosis is discussed. As far as we know, our cases are the first described from Brazil.     

Hb Johnstown [beta 109 (G11) Val-->Leu]: second case described and associated for the first time with beta(0)-thalassemia in two Spanish families

Hb Johnstown, a high oxygen affinity hemoglobin, was identified in four members from two unrelated Spanish families with erythrocytosis and left-shifted hemoglobin-oxygen dissociation curve. This hemoglobin variant, electrophoretically silent, was analyzed by reverse-phase high-performance liquid chromatography, and the mutation was characterized at the DNA level by beta gene sequencing. In one of these families, two members are affected with Hb Johnstown in association with beta(0)-thalassemia. In these cases the erythrocytosis and low values for P(50) due to Hb Johnstown remain in spite of the beta-thalassemia.     

A novel beta0-thalassemia mutation at codon 55 (-A) and a rare 17 bp deletion at codons 126-131 in the Indian population

A new mutation at codon 55 (-A) and a rare mutation, a 17 bp deletion at codons 126-131, that gives rise to beta0-thalassemia, were found in the Indian population by means of direct sequencing of two polymerase chain reaction products generated from a 2.3 kb DNA fragment containing the whole beta-globin gene. Each polymerase chain reaction product was sequenced on both strands in a mutation-loading format, showing all nucleotide substitutions or deletions/insertions, including mutations and polymorphisms, in the product. The entire protocol requires four sequencing reactions/gel loadings after two successive polymerase chain reactions, which simplifies the mutation search process and reduces the reading error rate.     

A deletional frameshift mutation of the beta-spectrin gene associated with elliptocytosis in spectrin Tokyo (beta 220/216).

A novel spectrin variant carrying a truncated beta-chain and designated Spectrin Tokyo (beta 220/216) is presented. It was associated with elliptocytosis and moderate uncompensated hemolysis. The dimer self-association was reduced. An increase of the alpha I 74-Kd fragment was detected upon partial trypsin digestion. Analysis of cDNA and genomic DNA showed a 1-base deletion in codon 2059 (GCC AGC-->GCA GCT; Ala-Ser-->Ala-Ala) that belongs to exon X of spectrin beta-gene. A missense sequence extended down to (new) codon 2075. Serine 2060, a potential phosphorylation site, was replaced by alanine. The shortened beta-chain failed to undergo phosphorylation in vitro. Spectrin Tokyo shared the same stop codon, overlapping normal codons 2076 and 2077 (CTG AAA), as Spectrin Nice (beta 220/216), which is caused by a dinucleotide insertion in codon 2046 and contains 2076 amino acids. However, for some reason, Spectrin Tokyo had a lower incorporation level into the membrane than Spectrin Nice.     

A novel nonsense mutation in the melanocortin-4 receptor associated with obesity in a Spanish population

BACKGROUND: In recent years, several groups have reported dominant inheritance of obesity conferred by missense, nonsense and frameshift mutations in the melanocortin 4 receptor gene (MC4R). Hence, MC4R is involved in the most common monogenic form of human obesity described so far. OBJECTIVES: In this context, we screened a Spanish population, composed of obese subjects and normal weight controls, for mutations in the MC4-R by single-strand conformational polymorphism (SSCP). SUBJECTS AND METHODS: Overall 313 individuals, 159 obese subjects (body mass index: BMI: 37.6 kg/m(2), 95% CI: 36.7-38.5 kg/m(2)) and 154 normal weight control subjects (BMI: 22.3 kg/m(2), 95% CI: 22.0-22.6 kg/m(2)) were screened for MC4-R mutations. RESULTS: We detected a novel nonsense mutation at codon 16 of the MC4-R in an obese female (BMI: 30.0 kg/m(2)) and a previously described missense mutation (Val-253-Ile) located within the sixth trans-membrane domain of the MC4-R in a normal weight individual (BMI: 19.0 kg/m(2)). The polymorphism Val-103-Ile was detected in one obese individual, while four subjects (two cases and two controls) with the polymorphism Ile-251-Leu were found. CONCLUSIONS: We have identified a novel nonsense mutation (Trp-16-Stop) that, based on previously described frameshift and nonsense mutations, most likely results in dominantly inherited obesity. Within this Spanish population, the frequency of the Ile-251-Leu polymorphism of the MC4R was similar in obese and control subjects (about 1.3%), while the polymorphism Val-103-Ile was only detected in an obese individual (0.6%).     

老年性黄斑变性的吲哚青绿脉络膜血管造影分析（附42例报告）

为探讨吲哚青绿血管造影（ICGA）对老年性黄斑变性（AMD）的诊断价值,应用德国产扫描激光检眼镜对AMD患者42例（70眼）进行了眼底荧光素血管造影（FFA）和ICGA,对比分析其图像特征。结果显示：①28眼为萎缩型AMD,其中16眼FFA仅有透见荧光或无明显改变,而ICGA则出现簇状强荧光点。②42眼为渗出型AMD,其中FFA诊断为典型脉络膜新生血管（CNV）12眼（占28．6％）,隐匿性CNV30眼（占71．4％）;ICGA诊断为典型CNV25眼（占59．5％）,典型CNV伴明显供养血管8眼。③FFA诊断为隐匿性CNV的30眼中,ICGA诊断为典型CNV13眼（占43．3％）。提示ICGA可提高AMD典型CNV的诊断率,发现CNV的供养血管,从而扩大了激光光凝治疗AMD的范围;另外,ICGA还可了解萎缩型AMD的病变程度。