Seungman Park

Revisit of multiple epiphyseal dysplasia: ethnic difference in genotypes and comparison of radiographic features linked to the COMP and MATN3 genes.

Multiple epiphyseal dysplasia (MED) is a genetically heterogeneous group of diseases characterized by variable degrees of epiphyseal abnormality primarily involving the hip and knee joints. The purpose of this study was to investigate the frequency of mutations in individuals with a clinical and radiographic diagnosis of MED and to test the hypothesis that characteristic radiological findings may be helpful in predicting the gene responsible. The radiographs of 74 Korean patients were evaluated by a panel of skeletal dysplasia experts. Six genes known to be associated with MED (COMP, MATN3, COL9A1, COL9A2, COL9A3, and DTDST) were screened by sequencing. Mutations were found in 55 of the 63 patients (87%). MATN3 mutations were found in 30 patients (55%), followed by COMP mutations in 23 (41%), and COL9A2 and DTDST mutations in one patient (2%) each. Comparisons of radiographic findings in patients with COMP and MATN3 mutations showed that albeit marked abnormalities in hip and knee joints were observed in both groups, the degree of involvement and the morphology of dysplastic epiphyses differed markedly. The contour of the pelvic acetabulum, the presence of metaphyseal vertical striations, and/or the brachydactyly of the hand were also found to be highly correlated with the genotypes. The study confirms that MATN3 and COMP are the genes most frequently responsible for MED and that subtle radiographic signs may give precious indications on which gene(s) should be prioritized for mutational screening in a given individual.

Identification of Two Novel NPM1 Mutations in Patients with Acute Myeloid Leukemia

Background Genetic abnormalities in adult AML are caused most frequently by somatic mutations in exon 12 of the NPM1 gene, which is observed in approximately 35% of AML patients and up to 60% of patients with cytogenetically normal AML (CN-AML). Methods We performed mutational analysis, including fragment analysis and direct sequencing of exon 12 of the NPM1 gene, on 83 AML patients to characterize the NPM1 mutations completely. Results In this study, NPM1 mutations were identified in 19 (22.9%) of the 83 AML patients and in 12 (42.9%) of the 28 CN-AML patients. Among the 19 patients with NPM1 mutations, type A NPM1 mutations were identified in 16 (84.2%) patients, whereas non-A type NPM1 mutations were observed in 3 (15.8%) patients. Two of the 3 non-A type NPM1 mutations were novel: c.867_868insAAAC and c.869_873indelCTTTAGCCC. These 2 novel mutant proteins display a nuclear export signal motif (L-xxx-L-xx-V-x-L) less frequently and exhibit a mutation at tryptophan 290 that disrupts the nucleolar localization signal. Conclusions This study suggests that novel NPM1 mutations may be non-rare and that supplementary sequence analysis is needed along with conventional targeted mutational analysis to detect non-A types of NPM1 mutations.

A case report of Fanconi anemia diagnosed by genetic testing followed by prenatal diagnosis.

Fanconi anemia (FA) is a rare genetic disorder affecting multiple body systems. Genetic testing, including prenatal testing, is a prerequisite for the diagnosis of many clinical conditions. However, genetic testing is complicated for FA because there are often many genes that are associated with its development, and large deletions, duplications, or sequence variations are frequently found in some of these genes. This study describes successful genetic testing for molecular diagnosis, and subsequent prenatal diagnosis, of FA in a patient and his family in Korea. We analyzed all exons and flanking regions of the FANCA, FANCC, and FANCG genes for mutation identification and subsequent prenatal diagnosis. Multiplex ligation-dependent probe amplification analysis was performed to detect large deletions or duplications in the FANCA gene. Molecular analysis revealed two mutations in the FANCA gene: a frameshift mutation c.2546delC and a novel splice-site mutation c.3627-1G>A. The FANCA mutations were separately inherited from each parent, c.2546delC was derived from the father, whereas c.3627-1G>A originated from the mother. The amniotic fluid cells were c.3627-1G>A heterozygotes, suggesting that the fetus was unaffected. This is the first report of genetic testing that was successfully applied to molecular diagnosis of a patient and subsequent prenatal diagnosis of FA in a family in Korea.

Identification of a GDF5 Mutation in a Korean Patient with Brachydactyly Type C without Foot Involvement

Brachydactyly type C (BDC) is characterized by shortening of the middle phalanges of the index, middle, and little fingers. Hyperphalangy of the index and middle finger and shortening of the first metacarpal can also be observed. BDC is a rare genetic condition associated with the GDF5 gene, and this condition has not been confirmed by genetic analysis so far in the Korean population. Herein, we present a case of a 6-yr-old girl diagnosed with BDC confirmed by molecular genetic analysis. The patient presented with shortening of the second and third digits of both hands. Sequence analysis of the GDF5 gene was performed and the pathogenic mutation, c.1312C>T (p.Arg438Cys), was identified. Interestingly, this mutation was previously described in a patient who presented with the absence of the middle phalanges in the second through fifth toes. However, our patient showed no involvement of the feet. Considering intrafamilial and interfamilial variability, molecular analysis of isolated brachydactyly is warranted to elucidate the genetic origin and establish a diagnosis.

The first study on nucleotide-level identification of Hb Koriyama in a patient with severe hemolytic anemia.

Hereditary hemolytic anemia comprises a group of disorders in which red blood cells are destroyed faster than they are produced in the bone marrow; various hereditary factors can cause this condition, including production of defective Hb and erythrocyte membrane. Recently, we identified Hb Koriyama, a rare Hb variant that was undetectable in Hb electrophoresis and stability tests, in a patient with severe hemolytic anemia. This is the first study to show the nucleotide-level sequence variations in Hb Koriyama. On the basis of our results, we conclude that unstable Hb may not be detectable by conventional Hb electrophoresis or stability tests. Thus, we suggest further genetic workup in cases of unexplained hereditary hemolytic anemia.

A case report of a male patient with Hb Hammersmith [β42(CD1)Phe→Ser, TTT>TCT].

All Hb Hammersmith [β42(CD1)Phe→Ser, TTT>TCT] patients reported so far have been female, suggesting that this condition may occur as a negative, fatal intrauterine selection against males. In this case report, we describe a male case of Hb Hammersmith. A 6-month-old male patient, born from ovum donation, presented with hemolytic anemia and cyanosis. Hemoglobin (Hb) electrophoresis revealed decreased Hb A (54.0%) and Hb A2 (0.3%) and markedly increased Hb F (45.7%) levels. Direct sequencing revealed a missense mutation in the HBB gene, c.128T>C (p.Phe42Ser), which is known as Hb Hammersmith. This mutation was not identified in any of this patient’s family members. This is the first case of Hb Hammersmith in a male patient, and this study demonstrates that Hb Hammersmith is likely a non fatal condition for males during the intrauterine period.

The First Case of Hb Köln [β98(FG5)Val→Met] in Korea

Hb Koln [β98(FG5)Val→Met] is the most common unstable hemoglobin (Hb) variant, causing hemolytic anemia of varying clinical severities (1). Hb Koln was first described in 1962, and the structural abnormality of the variant was determined in 1966 (2). The variant has increased oxygen affinity, and shows a left-shifted oxygen dissociation curve (3,4). The first case of Hb Koln in Koreans is described in this paper.

Performance of two commercially available BCR-ABL1 quantification assays that use an international reporting scale

Abstract Background: Quantifying the BCR-ABL1 rearrangement is important for monitoring chronic myelogenous leukemia (CML). To standardize BCR-ABL1 quantification, the World Health Organization (WHO) established the first international genetic reference panel. Here, we compared the BCR-ABL1 levels determined using international scale (IS)-based commercially available assays. Methods: BCR-ABL1 transcripts were quantified using two IS-based assays. 10–1, 10–2, 10–3, 10–4, 10–5 and 10–6 dilutions of the b3a2 positive RNA were used for evaluating linearity, precision, and limit of detection. Correlation of the assay was evaluated by using DNA obtained from CML patients carrying the BCR-ABL1 b3a2 and b2a2 types. Results: Both Ipsogen and Asuragen assays showed fine linearity with reasonable %CV. LOD of each assay was calculated as 0.003% for Ipsogen, and 0.005% for Asuragen. By comparing the results that were lower than 10% by either one of the assay, Ipsogen and Asuragen results showed an overall good linear correlation with a tendency for the Ipsogen assay to show slightly higher levels than the Asuragen assay for b3a2 transcript. For b2a2, the tendency was opposite, with Asuragen showing higher values than the Ipsogen. Conclusions: Two commercially available IS-based BCR-ABL1 assays showed an overall good quantitative correlation. It should be taken into consideration that each assay tended to produce higher values than the other, depending on the BCR-ABL1 subtypes, suggesting that a separate conversion factor for each subtype can be more helpful when BCR-ABL1 transcript levels are converted into IS.

P34.6 Response to propranolol and topiramate may be different in migraine patients according to the P100 amplitude of visual evoked potential

Masked face, a well-known sign of Parkinson’s disease (PD), generally refers to lack of facial expression, a phenomenon often associated with decreased blink rate. We studied the relation between blink rate and various conditions, such as expression, akinesia and disease severity, in patients with PD. The subjects were 14 healthy controls (mean age: 67.6 years) and 52 patients with PD (70.1 years). Blink rates per minute was measured two times with the subjects in a sitting position. The results are as follows.