OBJECTIVE: To explore the clinical and genetic characteristics of a boy with isolated maternal uniparental disomy of chromosome 20 [UPD(20)mat]. METHODS: A child who was admitted to the Tongji Hospital Affiliated to Tongji Medical College of Huazhong University of Science and Technology on April 8,2021. was selected as the study subject. Phenotypic and endocrinological findings of the child were retrospectively analyzed. Whole exome sequencing (WES) and methylation-specific multiplex ligation-dependent probe amplification (MS-MLPA) were carried out for detecting the UPD sequences and copy number variations. Both of his parents were verified by Sanger sequencing. Relevant literature was systematically reviewed. RESULTS: The child, a 3-year-and-8-month-old boy born to a 41-year-old mother by Cesarean delivery at 36⁺² gestational weeks due to oligohydramia, had a birth weight of 2 300 g and length of 46 cm. He was admitted to the NICU for feeding difficulties which had persisted despite of clinical management. At the age of 3.75, he had a height of 92.5 cm (< 3rd percentile; 25th ~ 50th percentile at 2.5 years) and a weight of 10.8 kg (< 3rd percentile; 50th percentile at 15 months). He had also presented with growth retardation, short stature, attention deficit and hyperactivity disorder (ADHD), mild mental retardation, and speech and language development disorders. He had simian creases in both hands but no additional dysmorphic signs, and his motor development was normal. Serum insulin, thyroid-stimulating hormone, and insulin growth factor binding protein 3 levels were within the normal ranges, though insulin growth factor-1 (IGF-1) was slightly decreased. Since that time he had continuously used atomoxetine hydrochloride capsules to control his ADHD. WES and MS-MLPA revealed the existence of UPD (20)mat. CONCLUSION The UPD(20)mat syndrome is characterized by feeding difficulties, growth retardation and short stature. The child in our case has been accompanied by ADHD and speech and language development disorders, which required long-term treatment. For women with advanced maternal age and suggestive phenotypes, genetic testing and counseling should be conducted.
Male ; Pregnancy ; Humans ; Child ; Female ; Infant ; Adult ; Chromosomes, Human, Pair 20 ; DNA Copy Number Variations ; Retrospective Studies ; Uniparental Disomy/genetics* ; Atomoxetine Hydrochloride ; Dwarfism ; Intercellular Signaling Peptides and Proteins ; Language Development Disorders ; Growth Disorders ; Insulins

Chromosomal loss in trisomy (trisomy rescue) to generate a disomic fetus can cause confined placental mosaicism and/or feto/placental mosaicism. After trisomy rescue event, there is a risk of fetal uniparental disomy (UPD). Noninvasive prenatal test (NIPT) reflects the genomic constitution of the placenta, not of the fetus itself. Feto-placental discrepancy can therefore cause false-positive (trisomy) NIPT results. These discordant NIPT results can serve as important clues to find UPD associated with confined placental mosaicism. We report a case with maternal UPD of chromosome 20, detected by NIPT of 1,000 high-risk pregnancies, carried out for detecting chromosomal abnormalities in Koreans.
Chromosome Aberrations ; Chromosomes, Human, Pair 20* ; Constitution and Bylaws ; Fetus ; Mosaicism ; Placenta ; Pregnancy, High-Risk* ; Trisomy ; Uniparental Disomy*

Pseudohypoparathyroidism type 1b (PHP 1b) is the result of end organ resistance to parathyroid hormone (PTH) in the absence of any features of Albright's hereditary osteodystrophy. There are two subtypes of PHP 1b with different genetic mechanisms. One subtype is related to a maternally derived 3kb microdeletion involving STX 16 gene, and is inherited in an autosomal dominant mode. Familial autosomal dominant inheritance of PHP 1b is relatively rare. The other subtype is associated with more extensive loss of imprinting at the GNAS locus that affects at least one additional differential methylated (hypermethylation at neuroendocrine secretory protein and hypomethylation at antisense transcript and or extra-large stimulatory G protein region) without microdeletion of the STX 16 or AS gene. It can be sporadic due to an imprinting defect in the GNAS gene. In our case, an 8-year-old girl was referred for suspected PHP with no feature of Albright hereditary osteodystrophy. Blood test results revealed hypocalcemia and hyperphosphatemia. Elevated PTH was also checked. There was no family history of endocrine or developmental problem. Her intelligence was normal, but she had inferior sociability at that time. Based on above, we diagnosed a rare case of paternal uniparental disomy of the long arm of chromosome 20 as the cause of PHP 1b by microsatellite marker test of chromosome 20.
Arm ; Child ; Chromosomes, Human, Pair 20 ; Female ; GTP-Binding Proteins ; Hematologic Tests ; Humans ; Hyperphosphatemia ; Hypocalcemia ; Intelligence ; Microsatellite Repeats ; Parathyroid Hormone ; Pseudohypoparathyroidism* ; Uniparental Disomy* ; Wills

OBJECTIVETo assess the association of 8 single nucleotide polymorphisms (SNPs) from chromosomes X and 20 with androgenetic alopecia among ethnic Han population from Yunnan province.

METHODSAn eight-SNP co-amplification protocol was developed for the genotyping with a SNaPshot platform. A case-control study was carried out for the 8 SNPs from chromosomes X and 20 in 115 androgenetic alopecia cases and 125 healthy controls. Statistical analysis was conducted with SPSS17.0, Haploview4.2, SHEsis and MDR software.

RESULTSNo association was found between the two groups with regard to the 4 SNPs located on the X chromosome. The genotypic frequencies of rs2180439, rs913063 and rs1160312 were significantly different between the two groups (P < 0.05). The frequency of T allele of rs2180439 was significantly higher in the case group (P < 0.05). The frequencies of A alleles of rs913063 and rs1160312 were significantly higher in the case group (P < 0.05). The haplotypes of C-T-C-G, T-C-C-G and T-T-A-A based on rs6137444-rs2180439-rs913063-rs1160312 showed significant difference between the two groups (P <0.05). rs6137444, rs21804393 and rs1160312 have a strong association with androgenetic alopecia.

CONCLUSIONThe 4 SNPs located on chromosome X were all monomorphic among ethnic Hans from Yunnan. The rs6152, rs16990427, rs1352015, rs1385699 SNPs located on chromosome 20 are associated with androgenetic alopecia in the same population. Individuals with T allele of rs2180439 and A allele of rs913063 and rs1160312 are more likely to develop androgenetic alopecia.

Adult ; Alopecia ; genetics ; Case-Control Studies ; China ; ethnology ; Chromosomes, Human, Pair 20 ; Chromosomes, Human, X ; Genotype ; Humans ; Male ; Middle Aged ; Polymorphism, Single Nucleotide

Non-coding expansion spinocerebellar ataxias (SCAs) are a group of autosomal dominant neurodegenerative diseases characterized by "CTA/CTG", "ATTCT", "TGGAA" expansion in non-coding region of the causative gene. Until now, 5 subtypes including SCA8, SCA10, SCA12, SCA31 and SCA36 have been mapped. Recently, the causative mutation for SCA36, namely intronic hexanucleotide GGCCTG expansion in NOP56 gene, has been identified in Japanese and Spanish pedigrees in succession. Compared with other subtypes of SCAs, there are certain distinctive characteristics for SCA36. The clinical and genetic features of SCA36 are reviewed in this paper.
Base Sequence ; Biomedical Research ; methods ; trends ; Chromosome Mapping ; Chromosomes, Human, Pair 20 ; genetics ; DNA Repeat Expansion ; genetics ; Genetic Predisposition to Disease ; genetics ; Humans ; Nuclear Proteins ; genetics ; Oligonucleotides ; genetics ; Spinocerebellar Ataxias ; genetics ; pathology

OBJECTIVETo correlate the presence of chromosome 1p/19q deletion with the expression of R132H mutant IDH1 status in oligodendroglial tumors, and to explore molecular markers for predicting chemosensitivity of oligodendroglial tumors.

METHODSThe study included 75 oligodendroglial tumors (38 oligodendrogliomas and 37 oligoastrocytomas). Immunohistochemistry was used to detect the expression of R132H mutant IDH1 protein, and fluorescence in situ hybridization (FISH) was employed to detect 1p/19q deletion.

RESULTSDeletion of chromosome 1p and/or 19q was detected in 37 cases (37/75, 49.3%), among which co-deletion of 1p and 19q was seen in 34 cases (closely correlated, P < 0.01). Oligodendrogliomas WHOIIhad a slightly higher deletion rate than oligodendrogliomas WHO III, although without statistical significance. Oligodendrogliomas WHO IIand WHO III had a significantly higher deletion rate of chromosome 1p/19q than oligoastrocytomas WHO II and WHO III (P < 0.05). While combined loss of 1p/19q was always detected in oligodendrogliomas when FISH was positive, isolated 1p or 19q deletion was only found in oligoastrocytomas. The expression of R132H mutant IDH1 was detected in 51 of 75 cases (68.0%), in which oligodendrogliomas had a higher positive rate than oligoastrocytomas. Statistical analysis demonstrated a significant correlation between the expression of R132H mutant IDH1 protein and the presence of combined 1p/19q deletion in oligodendrogliomas (P < 0.05).

CONCLUSIONSA significant correlation was observed between the expression of R132H mutant protein and 1p/19q LOH.Expression of 132H mutant IDH1 protein is the potential biomarker for predicating the presence of 1p/19q deletion in oligodendrogliomas.

Aged ; Brain Neoplasms ; genetics ; metabolism ; Chromosome Deletion ; Chromosomes, Human, 19-20 ; genetics ; Chromosomes, Human, Pair 1 ; Humans ; Immunohistochemistry ; In Situ Hybridization, Fluorescence ; Isocitrate Dehydrogenase ; genetics ; metabolism ; Middle Aged ; Mutant Proteins ; metabolism ; Neoplasm Proteins ; genetics ; metabolism ; Oligodendroglioma ; genetics ; metabolism

Anticonvulsants ; administration & dosage ; therapeutic use ; Brain ; diagnostic imaging ; physiopathology ; Child ; Child, Preschool ; Chromosome Deletion ; Chromosome Disorders ; diagnosis ; genetics ; Chromosomes, Human, Pair 20 ; genetics ; Electroencephalography ; Epilepsy ; diagnosis ; drug therapy ; genetics ; Epilepsy, Complex Partial ; diagnosis ; drug therapy ; genetics ; Humans ; Karyotyping ; Radiography ; Ring Chromosomes

Isolated deletion of the long arm of chromosome 20 [del(20q12)] is a rare abnormality in patients with de novo myelodysplastic syndrome. It is characterised by refractory thrombocytopenia, minimal haematological dysplasia and a lower risk for progression to acute myeloid leukaemia. Its distinction from chronic autoimmune thrombocytopenia, although clinically and morphologically difficult, is critical. We report a case of refractory cytopenia and unilineage dysplasia in an elderly woman with isolated del(20q12), identified via fluorescence in situ hybridisation analysis of her bone marrow. In order to avoid a misdiagnosis, we suggest that cytogenetic analysis be performed on all patients suspected to have myelodysplastic syndrome with predominant thrombocytopenic presentation.
Aged ; Biopsy, Needle ; Bone Marrow Cells ; pathology ; Chromosome Deletion ; Chromosomes, Human, Pair 20 ; Female ; Flow Cytometry ; Humans ; In Situ Hybridization, Fluorescence ; Myelodysplastic Syndromes ; diagnosis ; genetics

This study was undertaken to identify genetic polymorphisms that are associated with the risk of an elevated fasting glucose (FG) level using genome-wide analyses. We explored a quantitative trait locus (QTL) for FG level in a genome-wide study from a Korean twin-family cohort (the Healthy Twin Study) using a combined linkage and family-based association analysis approach. We investigated 1,754 individuals, which included 432 families and 219 pairs of monozygotic twins. Regions of chromosomes 2q23.3-2q31.1, 15q26.1-15q26.3, 16p12.1, and 20p13-20p12.2, were found to show evidence of linkage with FG level, and several markers in these regions were found to be significantly associated with FG level using family-based or general association tests. In particular, a single-nucleotide polymorphism (rs6138953) on the PTPRA gene in the 20p13 region (combined P = 1.8 x 10(-6)) was found to be associated with FG level, and the PRKCB1 gene (in 16p12.1) to be possibly associated with FG level. In conclusion, multiple regions of chromosomes 2q23.3-2q31.1, 15q26.1-15q26.3, 16p12.1, and 20p13-20p12.2 are associated with FG level in our Korean twin-family cohort. The combined approach of genome-wide linkage and family-based association analysis is useful to identify novel or known genetic regions concerning FG level in a family cohort study.
Adult ; Aged ; Asian Continental Ancestry Group/*genetics ; Blood Glucose/*genetics ; Chromosomes, Human, Pair 15/genetics ; Chromosomes, Human, Pair 16/genetics ; Chromosomes, Human, Pair 2/genetics ; Chromosomes, Human, Pair 20/genetics ; Cohort Studies ; Family ; Female ; *Genetic Linkage ; *Genome-Wide Association Study ; Genotype ; Humans ; Male ; Middle Aged ; Polymorphism, Single Nucleotide ; Protein Kinase C/genetics ; Quantitative Trait Loci ; Receptor-Like Protein Tyrosine Phosphatases, Class 4/*genetics ; Republic of Korea ; Twins, Monozygotic/*genetics

OBJECTIVETo analyze clinical and cytogenetic features of hematological disorders associated with 20q- and t (20;21) (q11;q11) abnormalities.

METHODSFollowing short-term culture of bone marrow cells, karyotypic analysis was carried out with R-banding. 20q- and t(20;21) (q11;q11) was detected by fluorescence in situ hybridization (FISH) using dual-color 20q11/12 probe, ST 20qter /ST 21qter probes, SE20(D20Z1)/SE 13/21 probes, and WC20/WC21 probes.

RESULTSSix (2.3%) of the 257 patients with 20q- detected by conventional karyotypic analysis were found to have t(20;21) (q11;q11) abnormality. Five cases had myelodysplastic syndrome, 1 had acute lymphoblastic leukemia. Above results were all confirmed by FISH.

CONCLUSIONi (20q-), t(20;21) (q11;q11) seems to be a rare but recurrent chromosomal abnormality which is specifically associated with myeloid disease, late occurrence and poor prognosis. The translocation between chromosome 20q11 and 21q11 may form a novel fusion gene which has an important role in the pathogenesis of the disease.

Aged ; Chromosome Deletion ; Chromosomes, Human, Pair 20 ; Chromosomes, Human, Pair 21 ; Female ; Humans ; In Situ Hybridization, Fluorescence ; Male ; Middle Aged ; Myelodysplastic Syndromes ; genetics ; Precursor Cell Lymphoblastic Leukemia-Lymphoma ; genetics ; Translocation, Genetic