A Profile of Glucose-6-Phosphate Dehydrogenase Variants and Deficiency of Multicultural Families in Korea

Vivax malaria incidence in Korea is now decreased and showing a low plateau. Nowadays, vivax malaria in Korea is expected to be successfully eliminated with anti-malaria chemotherapy, primaquine, and vector control. The glucose-6-phosphate dehydrogenase (G6PD) deficiency is associated with potential hemolytic anemia after primaquine administration. This inborn disorder has a pivotal polymorphism with genetic variants and is the most prevalent X-chromosome-linked disorder. The prevalence of G6PD deficiency was previously reported negligible in Korea. As the population of multicultural families pertaining marriage immigrants and their adolescents increases, it is necessary to check G6PD deficiency for them prior to primaquine treatment for vivax malaria. The prevalence of G6PD variants and G6PD deficiency in multicultural families was performed in 7 counties and 2 cities of Jeollanam-do (Province), Gyeonggi-do, and Gangwon-do. A total of 733 blood samples of multicultural family participants were subjected to test the phenotypic and genetic G6PD deficiency status using G6PD enzyme activity quantitation kit and PCR-based G6PD genotyping kit. The G6PD phenotypic deficiency was observed in 7.8% of male adolescent participants and 3.2% of materfamilias population. Based on the PCR-based genotyping, we observed total 35 participants carrying the mutated alleles. It is proposed that primaquine prescription should seriously be considered prior to malaria treatment.

A case of follow-up of a patient with 22q11.2 distal deletion syndrome and a review of the literature

Microdeletions of chromosome 22q11.2 are one of the most common microdeletions occurring in humans, and is known to be associated with a wide range of highly variable features. These deletions occur within a cluster of low copy repeats (LCRs) in 22q11.2, referred to as LCR22 A-H. DiGeorge (DGS)/velocardiofacial syndrome is the most prevalent form of a 22q11.2 deletions, caused by mainly proximal deletions between LCR22 A and D. As deletions of distal portion to the DGS deleted regions has been extensively studied, the recurrent distal 22q11.2 microdeletions distinct from DGS has been suggested as several clinical entities according to the various in size and position of the deletions on LCRs. We report a case of long-term follow-up of a female diagnosed with a 22q11.2 distal deletion syndrome, identified a deletion of 1.9 Mb at 22q11.21q11.23 (chr22: 21,798,906-23,653,963) using single nucleotide polymorphism array. This region was categorized as distal deletion type of 22q11.2, involving LCR22 D-F. She was born as a preterm, low birth weight to healthy non-consanguineous Korean parents. She showed developmental delay, growth retardation, dysmorphic facial features, and mild skeletal deformities. The patient underwent a growth hormone administration due to growth impairment without catch-up growth. While a height gain was noted, she had become overweight and was subsequently diagnosed with pre-diabetes. Our case could help broaden the genetic and clinical spectrum of 22q11.2 distal deletions.

A newborn with developmental delay diagnosed with 4q35 deletion and 10p duplication

We report the case of an infant with a 4q35.1 deletion with 10p duplication. This mutation is rarely reported in the literature and has been found to have variable clinical findings, often including developmental delay. In this case, the condition was detected by chromosomal microarray analysis after initial manifestation of a feeding problem and developmental delay. Minor dysmorphic features with abnormal neurological examination led to further evaluation. The father’s chromosome complement was 46, XY, t(4;10)(q35;p12.2). Parental balanced translocation can go unrecognized, because affected individuals are often phenotypically healthy until they have fertility issues such as recurrent miscarriages or children with severe congenital disorders. Genetic diagnoses help to establish a clear family genetic background that permits the development of clear treatment strategies. Prenatal counseling can also help to understand the possible risks associated with pregnancy or future child planning.

A newborn with developmental delay diagnosed with 4q35 deletion and 10p duplication

We report the case of an infant with a 4q35.1 deletion with 10p duplication. This mutation is rarely reported in the literature and has been found to have variable clinical findings, often including developmental delay. In this case, the condition was detected by chromosomal microarray analysis after initial manifestation of a feeding problem and developmental delay. Minor dysmorphic features with abnormal neurological examination led to further evaluation. The father’s chromosome complement was 46, XY, t(4;10)(q35;p12.2). Parental balanced translocation can go unrecognized, because affected individuals are often phenotypically healthy until they have fertility issues such as recurrent miscarriages or children with severe congenital disorders. Genetic diagnoses help to establish a clear family genetic background that permits the development of clear treatment strategies. Prenatal counseling can also help to understand the possible risks associated with pregnancy or future child planning.

Chromosomal Microarray Analysis as a First-Tier Clinical Diagnostic Test in Patients With Developmental Delay/Intellectual Disability, Autism Spectrum Disorders, and Multiple Congenital Anomalies: A Prospective Multicenter Study in Korea

BACKGROUND: To validate the clinical application of chromosomal microarray analysis (CMA) as a first-tier clinical diagnostic test and to determine the impact of CMA results on patient clinical management, we conducted a multicenter prospective study in Korean patients diagnosed as having developmental delay/intellectual disability (DD/ID), autism spectrum disorders (ASD), and multiple congenital anomalies (MCA). METHODS: We performed both CMA and G-banding cytogenetics as the first-tier tests in 617 patients. To determine whether the CMA results directly influenced treatment recommendations, the referring clinicians were asked to complete a 39-item questionnaire for each patient separately after receiving the CMA results. RESULTS: A total of 122 patients (19.8%) had abnormal CMA results, with either pathogenic variants (N=65) or variants of possible significance (VPS, N=57). Thirty-five well-known diseases were detected: 16p11.2 microdeletion syndrome was the most common, followed by Prader-Willi syndrome, 15q11-q13 duplication, Down syndrome, and Duchenne muscular dystrophy. Variants of unknown significance (VUS) were discovered in 51 patients (8.3%). VUS of genes putatively associated with developmental disorders were found in five patients: IMMP2L deletion, PTCH1 duplication, and ATRNL1 deletion. CMA results influenced clinical management, such as imaging studies, specialist referral, and laboratory testing in 71.4% of patients overall, and in 86.0%, 83.3%, 75.0%, and 67.3% of patients with VPS, pathogenic variants, VUS, and benign variants, respectively. CONCLUSIONS: Clinical application of CMA as a first-tier test improves diagnostic yields and the quality of clinical management in patients with DD/ID, ASD, and MCA.

Reclassification of Acute Myeloid Leukemia According to the 2016 WHO Classification

We reviewed our leukemia database to reclassify 610 patients previously diagnosed as having acute myeloid leukemia (AML) according to the updated 2016 WHO classification. Nine patients were categorized as having myelodysplastic syndrome and myeloid neoplasms with germline predisposition. AML with recurrent genetic abnormalities accounted for 57.4% (345/601) of the patients under the 2016 WHO classification. AML with mutated NPM1 was the most common form (16.5%), with the majority associated with monocytic differentiation (63.6%). AML with double CEBPA mutations accounted for 8.3% of these cases, and the majority were previously diagnosed as AML with/without maturation (78.0%). These newly classified mutations were mutually exclusive without overlapping with other forms of AML with recurrent genetic abnormalities. AML with mutated NPM1 and AML with myelodysplasia-related changes comprised the oldest patients, whereas AML with RUNX1-RUNX1T1 included the youngest patients. The leukocyte count was highest in AML with mutated NPM1, and the percentage of peripheral blood blasts was the highest in AML with double CEBPA mutations. Our results indicate that implementation of the 2016 WHO classification of AML would not pose major difficulties in clinical practice. Hematopathologists should review and prepare genetic tests for the new classification, according to their clinical laboratory conditions.

Effects of Copy Number Variations on Developmental Aspects of Children With Delayed Development

OBJECTIVE: To determine effects of copy number variations (CNV) on developmental aspects of children suspected of having delayed development. METHODS: A retrospective chart review was done for 65 children who underwent array-comparative genomic hybridization after visiting physical medicine & rehabilitation department of outpatient clinic with delayed development as chief complaints. Children were evaluated with Denver Developmental Screening Test II (DDST-II), Sequenced Language Scale for Infants (SELSI), or Preschool Receptive-Expressive Language Scale (PRES). A Mann-Whitney U test was conducted to determine statistical differences of developmental quotient (DQ), receptive language quotient (RLQ), and expressive language quotient (ELQ) between children with CNV (CNV(+) group, n=16) and children without CNV (CNV(–) group, n=37). RESULTS: Of these subjects, the average age was 35.1 months (mean age, 35.1±24.2 months). Sixteen (30.2%) patients had copy number variations. In the CNV(+) group, 14 children underwent DDST-II. In the CNV(–) group, 29 children underwent DDST-II. Among variables, gross motor scale was significantly (p=0.038) lower in the CNV(+) group compared with the CNV(–) group. In the CNV(+) group, 5 children underwent either SELSI or PRES. In the CNV(–) group, 27 children underwent above language assessment examination. Both RLQ and ELQ were similar between the two groups. CONCLUSION: The gross motor domain in DQ was significantly lower in children with CNV compared to that in children without CNV. This result suggests that additional genetic factors contribute to this variability. Active detection of genomic imbalance could play a vital role when prominent gross motor delay is presented in children with delayed development.

Two Korean Cases of Hereditary Spherocytosis Caused by Mutations in SLC4A1

Hereditary spherocytosis (HS) is caused by mutations in the SPTA1, SPTB, ANK1, SLC4A1, and EPB42 genes, all of which encode erythrocyte membrane proteins. Mutations in SLC4A1, which encodes band 3 protein, have rarely been reported as the causative factor among Korean patients with HS. Here, we report two Korean patients with HS carrying mutations in SLC4A1. Patient 1 was a 3-year-old girl with unremarkable past and family histories and was evaluated for anemia that was detected after a complete blood count. She was suspected of having HS considering the spherocytosis of her peripheral blood smear, increased osmotic fragility, hemolytic features in blood chemistry tests, and splenomegaly. Sequence analysis revealed that the patient harbored a single heterozygous missense mutation, c.2278C>T (p.Arg760Trp) in exon 17 of SLC4A1. Patient 2 was a 23-year-old man who had a prior history of intermittent jaundice. Although the patient did not have anemia, a genetic test for HS was performed due to evidence of hemolytic features in the blood chemistry test, splenomegaly, and a family history of HS. The test confirmed a single heterozygous missense mutation, c.2423G>T (p.Arg808Leu) in exon 18 of SLC4A1.

Nonautoimmune congenital hyperthyroidism due to p.Asp633Glu mutation in the TSHR gene

Most cases of congenital hyperthyroidism are autoimmune forms caused by maternal thyroid stimulating antibodies. Nonautoimmune forms of congenital hyperthyroidism caused by activating mutations of the thyrotropin receptor (TSHR) gene are rare. A woman gave birth to a boy during an emergency cesarean section at 33 weeks of gestation due to fetal tachycardia. On the 24th day of life, thyroid function tests were performed due to persistent tachycardia, and hyperthyroidism was confirmed. Auto-antibodies to TSHR, thyroid peroxidase, and thyroglobulin were not found. The patient was treated with propylthiouracil and propranolol, but hyperthyroidism was not well controlled. At 3 months of age, the patient had craniosynostosis and hydrocephalus, and underwent a ventriculoperitoneal shunt operation. Direct sequencing of the TSHR gene showed a heterozygous mutation of c.1899C>A (p.Asp633Glu) in exon 10. No mutations were discovered in any of the parents in a familial genetic study. We have reported a case of sporadic nonautoimmune congenital hyperthyroidism, by a missense mutation of the TSHR gene, for the first time in South Korea.

Hemoglobin Kansas: First Korean Family and Literature Review

No abstract available.

Hemoglobin Kansas: First Korean Family and Literature Review

No abstract available.

A Case of Pseudohypoparathyroidism Type Ib Caused by Aberrant Methylation in the GNAS Complex Locus

Pseudohypoparathyroidism (PHP) is a rare disorder caused by genetic and epigenetic aberrations in the GNAS complex locus resulting in impaired expression of stimulatory G protein (Gsα). PHP type Ib (PHP-Ib) is characterized by hypocalcemia and hyperphosphatemia due to renal resistance to the parathyroid hormone, and is distinguished from PHP-Ia by the absence of osteodystrophic features. An 11-yr-old boy presented with poor oral intake and cramping lower limb pain after physical activity. Laboratory studies revealed hypocalcemia, hyperphosphatemia, and increased parathyroid hormone levels. The GNAS complex locus was evaluated using the methylation-specific multiplex ligation-dependent probe amplification (MS-MLPA) assay. Gain of methylation in the NESP55 domain and loss of methylation in the antisense (AS) transcript, XL, and A/B domains in the maternal allele were observed. Consequently, we present a case of PHP-Ib diagnosed using MS-MLPA.

Birt-Hogg-Dubé Syndrome Manifesting as Spontaneous Pneumothorax: A Novel Mutation of the Folliculin Gene

Birt-Hogg-Dubé syndrome (BHDS) is a rare disease with autosomal dominant inheritance that manifests through skin tumors, pulmonary cystic lesions, and renal tumors. A mutation of FLCN located on chromosome 17p11.2, which encodes a tumor-suppressor protein (folliculin), is responsible for the development of BHDS. We report the case of a patient presenting with spontaneous pneumothorax, in whom a familial genetic study revealed a novel nonsense mutation: p.(Arg379*) in FLCN.

Birt-Hogg-Dubé Syndrome Manifesting as Spontaneous Pneumothorax: A Novel Mutation of the Folliculin Gene

Birt-Hogg-Dubé syndrome (BHDS) is a rare disease with autosomal dominant inheritance that manifests through skin tumors, pulmonary cystic lesions, and renal tumors. A mutation of FLCN located on chromosome 17p11.2, which encodes a tumor-suppressor protein (folliculin), is responsible for the development of BHDS. We report the case of a patient presenting with spontaneous pneumothorax, in whom a familial genetic study revealed a novel nonsense mutation: p.(Arg379*) in FLCN.

Fragment Analysis for Detection of the FLT3-Internal Tandem Duplication: Comparison with Conventional PCR and Sanger Sequencing

BACKGROUND: We evaluated a sensitive and quantitative method utilizing fragment analysis of the fms-like tyrosine kinase 3-internal tandem duplication (FLT3-ITD), simultaneously measuring mutant allele burden and length, and verified the analytical performance. METHODS: The number and allelic burden of FLT3-ITD mutations was determined by fragment analysis. Serial mixtures of mutant and wild-type plasmid DNA were used to calculate the limit of detection of fragment analysis, conventional PCR, and Sanger sequencing. Specificity was evaluated using DNA samples derived from 50 normal donors. Results of fragment analysis were compared to those of conventional PCR, using 481 AML specimens. RESULTS: Defined mixtures were consistently and accurately identified by fragment analysis at a 5% relative concentration of mutant to wild-type, and at 10% and 20% ratios by conventional PCR and direct sequencing, respectively. No false positivity was identified. Among 481 AML specimens, 40.1% (193/481) had FLT3-ITD mutations. The mutant allele burden (1.7-94.1%; median, 28.2%) and repeated length of the mutation (14-153 bp; median, 49 bp) were variable. The concordance rate between fragment analysis and conventional PCR was 97.7% (470/481). Fragment analysis was more sensitive than conventional PCR and detected 11 additional cases: seven had mutations below 10%, three cases represented conventional PCR failure, and one case showed false negativity because of short ITD length (14 bp). CONCLUSIONS: The new fragment analysis method proved to be sensitive and reliable for the detection and monitoring of FLT3-ITD in patients with AML. This could be used to simultaneously assess ITD mutant allele burden and length.

Phenotype of a Patient With a 1p36.11-p35.3 Interstitial Deletion Encompassing the AHDC1

No abstract available.

Patient With Delayed Development Resulting From De Novo Duplication of 7q36.1-q36.3 and Deletion of 9p24.3

Patients with a duplication from 7q36 to the terminus or a deletion of 9p24 have been reported, whereas those harboring both mutations have not. Here, we report a patient with simultaneous de novo 7q36.1-q36.3 duplication and 9p24.3 deletion. A 6-year-old boy presented with speech developmental delay, microcephaly, and dysmorphic features, including a long face and small nose. Chromosome and array comparative genomic hybridization analyses revealed 46,XY,dup(7)(q36.1-q36.3) and del(9)(p24.3). The sizes of the duplication and deletion were 9.9 Mb and 1.9 Mb, respectively. The duplication of chromosome 7 contained 68 known genes, of which 3 are related with entries in the Developmental Disorders Genotype-to-Phenotype (DDG2P) database. The deletion of chromosome 9 contained 6 known genes, of which 2 are in the DDG2P database. We investigated the genotype and phenotype in this patient, and reviewed the relevant literatures for possible clinical presentation in these variations.

Genetic Profiles of Korean Patients With Glucose-6-Phosphate Dehydrogenase Deficiency

BACKGROUND: We describe the genetic profiles of Korean patients with glucose-6-phosphate dehydrogenase (G6PD) deficiencies and the effects of G6PD mutations on protein stability and enzyme activity on the basis of in silico analysis. METHODS: In parallel with a genetic analysis, the pathogenicity of G6PD mutations detected in Korean patients was predicted in silico. The simulated effects of G6PD mutations were compared to the WHO classes based on G6PD enzyme activity. Four previously reported mutations and three newly diagnosed patients with missense mutations were estimated. RESULTS: One novel mutation (p.Cys385Gly, labeled G6PD Kangnam) and two known mutations [p.Ile220Met (G6PD São Paulo) and p.Glu416Lys (G6PD Tokyo)] were identified in this study. G6PD mutations identified in Koreans were also found in Brazil (G6PD São Paulo), Poland (G6PD Seoul), United States of America (G6PD Riley), Mexico (G6PD Guadalajara), and Japan (G6PD Tokyo). Several mutations occurred at the same nucleotide, but resulted in different amino acid residue changes in different ethnic populations (p.Ile380 variant, G6PD Calvo Mackenna; p.Cys385 variants, Tomah, Madrid, Lynwood; p.Arg387 variant, Beverly Hills; p.Pro396 variant, Bari; and p.Pro396Ala in India). On the basis of the in silico analysis, Class I or II mutations were predicted to be highly deleterious, and the effects of one Class IV mutation were equivocal. CONCLUSIONS: The genetic profiles of Korean individuals with G6PD mutations indicated that the same mutations may have arisen by independent mutational events, and were not derived from shared ancestral mutations. The in silico analysis provided insight into the role of G6PD mutations in enzyme function and stability.

Genetic–pathologic characterization of myeloproliferative neoplasms

Myeloproliferative neoplasms (MPNs) are clonal hematopoietic stem cell disorders characterized by the proliferation of one or more myeloid lineages. The current study demonstrates that three driver mutations were detected in 82.6% of 407 MPNs with a mutation distribution of JAK2 in 275 (67.6%), CALR in 55 (13.5%) and MPL in 6 (1.5%). The mutations were mutually exclusive in principle except in one patient with both CALR and MPL mutations. The driver mutation directed the pathologic features of MPNs, including lineage hyperplasia, laboratory findings and clinical presentation. JAK2-mutated MPN showed erythroid, granulocytic and/or megakaryocytic hyperplasia whereas CALR- and MPL-mutated MPNs displayed granulocytic and/or megakaryocytic hyperplasia. The lineage hyperplasia was closely associated with a higher mutant allele burden and peripheral cytosis. These findings corroborated that the lineage hyperplasia consisted of clonal proliferation of each hematopoietic lineage acquiring driver mutations. Our study has also demonstrated that bone marrow (BM) fibrosis was associated with disease progression. Patients with overt fibrosis (grade ⩾2) presented an increased mutant allele burden (P<0.001), an increase in chromosomal abnormalities (P<0.001) and a poor prognosis (P<0.001). Moreover, among patients with overt fibrosis, all patients with wild-type JAK2/CALR/MPL (triple-negative) showed genomic alterations by genome-wide microarray study and revealed the poorest overall survival, followed by JAK2-mutated MPNs. The genetic–pathologic characteristics provided the information for understanding disease pathogenesis and the progression of MPNs. The prognostic significance of the driver mutation and BM fibrosis suggests the necessity of a prospective therapeutic strategy to improve the clinical outcome.

Comparison of Targeted Next-Generation and Sanger Sequencing for the BRCA1 and BRCA2 Mutation Screening

No abstract available.