China
Africa
Explore chapters and articles related to this topic
Basic genetics and patterns of inheritance
Published in Hung N. Winn, Frank A. Chervenak, Roberto Romero, Clinical Maternal-Fetal Medicine Online, 2021
There are four basic inheritance patterns of human single-gene disorders. These include autosomal dominant and autosomal recessive inheritance, in which the mutant gene is on an autosome, and X-linked dominant and X-linked recessive inheritance, in which the mutant gene is on the X chromosome. Individuals can be heterozygous for a given gene, meaning that they have two different forms, or alleles, of the gene at the same locus on each of the two different chromosomes. Individuals can also be homozygous for a gene, in which the two alleles are identical. Males are said to be hemizygous with respect to genes on the X chromosome, since they have only one copy of the X.
An Approach to Inherited Pulmonary Disease
Published in Stephen D. Litwin, Genetic Determinants of Pulmonary Disease, 2020
The term phenotype can be applied to any property observable in an organism or in specimens obtained from an organism. By genetic analysis phenotypes can be attributed to the action of certain genes whose presence in an individual organism is inferred from the phenotype and the pedigree. The complement of genes present in an organism is called the genotype. In diploid organisms such as humans there are two complete sets of the genes carried on the autosomes, those chromosomes other than the X and Y. A pair of genes occupies a specific place in the genome called a locus. Commonly the term genotype is used in reference to only the two genes at the one locus relevant to a specific phenotype. Alternative forms of a gene which can occupy the same locus are called alleles. An individual who has two different genes at one locus is said to be heterozygous at that locus, or a heterozygote. An individual who has two copies of the same gene at one locus is said to be homozygous at that locus, or a homozygote.
Preimplantation Genetic Testing in the Future
Published in Darren K. Griffin, Gary L. Harton, Preimplantation Genetic Testing, 2020
Joe Leigh Simpson, Svetlana Rechitsky, Anver Kuliev
Initially, PGT-M for monogenic disorders was performed because a couple had an affected child (proband). The very first PGT cases were for this indication, either X-linked (ornithine transcarbamylase [OTC] deficiency) or autosomal recessive (cystic fibrosis) conditions. In such disorders, a parent or parents could be deduced to be obligate heterozygotes, at 25% risk for another affected child. Thus, subsequent testing pregnancies was indicated.
Whole genome sequencing and inheritance-based variant filtering as a tool for unraveling missing heritability in pediatric cancer
Published in Pediatric Hematology and Oncology, 2023
Charlotte Derpoorter, Ruben Van Paemel, Katrien Vandemeulebroecke, Jolien Vanhooren, Bram De Wilde, Geneviève Laureys, Tim Lammens
Identification of candidate variants was performed using an inheritance-based filtering approach. This strategy filters variants according to genotype requirements that meet an autosomal dominant, recessive or compound heterozygous inheritance pattern in this family. More specifically, in an autosomal dominant model, patients and obligate carriers must be heterozygous and unrelated spouses must be homozygous reference. In a recessive model, both patients must be homozygous alternative and their parents should be heterozygous. Other family members cannot be homozygous alternative. In a compound heterozygous inheritance, the phenotype is caused by two heterozygous recessive alleles at different loci in a particular gene and variants were filtered accordingly. In addition, exonic and non-exonic variants were compared respectively to the databases ExAC (non-Finnish European subset, ExAC-NFE)13 and 1000 Genomes (European subset, 1000G-EUR)14 for their absence or rarity in the general population (allele frequency (AF) ≤ 0.01).
Identification of Three Families Carrying Hb Anti-Lepore Hong Kong Variant in Guangxi, China, and Analysis of Their Hematological Data
Published in Hemoglobin, 2022
Ju Long, Feifei Gong, Lei Sun, Guangping Lai, Lihua Chen, Mingkui Peng, Chunhui Yu, Enqi Liu
In the large number of thalassemia carriers, the α-globin gene cluster (NG_000006.1) and the β-globin gene cluster (NG_000007.3) that cause thalassemia, have larger homologous segments. Therefore, there is a certain probability of forming a fusion gene. The variants in the α-globin gene cluster carrying fusion genes identified in the population in this region include HKαα, Anti-HKαα, αααanti3.7, αααanti4.2 and α fusion, and others [13]. Most of these variants lead to increased expression of specific genes. Heterozygous carriers are usually asymptomatic but when heterozygous for a pathogenic allele, this may lead to individuals with thalassemia or cause specific significant anomalies in indicators. The Hb Anti-Lepore Hong Kong causes an abnormal increase in Hb A2 level in carriers. Although this variant does not cause serious thalassemia results, the simple abnormal Hb A2 index cannot be used as a diagnostic indicator for Anti-Lepore Hong Kong, and genetic analysis is needed to verify. When Hb A2 screening is abnormal, further analysis is needed to determine the molecular biological characteristics and to provide clear genetic counseling for carriers.
DNA repair in lung cancer: a large-scale quantitative analysis for polymorphisms in DNA repairing pathway genes and lung cancer susceptibility
Published in Expert Review of Respiratory Medicine, 2022
Zexi Liao, Minhan Yi, Jiaxin Li, Yuan Zhang
Meta-analyses were conducted through Revman Manager 5.3 software (https://training.cochrane.org/online-learning/core-software-cochrane-reviews/revman). Quantitative analyses of variants were carried out in the total population as well as in subpopulations by ethnicity (including East Asian, European Caucasian/West Asian, African, Latino, and Mixed) or LC subtypes (including SCLC and NSCLC, the later could be further divided into SQCC, ADC, and other subtypes). The allele model was used to determine the relationship between variants and LC risk. The dominant and recessive models were utilized to analyze the contributions of heterozygotes as well as homozygotes. Allele frequencies (AFs) were calculated in total population and in different subgroups. Pooled odds ratios (ORs) and 95% CIs were used to evaluate the significance of results, and the limitation of p-value is set at less than 0.05. Q and I2 were used to choose model for demonstration of heterogeneity of the analysis. A fixed-effects model was chosen if Q statistic I2 ≤ 50% while a random-effects model was applied if Q statistic I2 > 50%.