Carrier testing
Angus Clarke, Alex Murray, Julian Sampson in Harper's Practical Genetic Counselling, 2019
This chapter explores the range and limitations of tests of carrier status and attempts to show how the information can be used in conjunction with other genetic and clinical data to make as accurate a determination as possible. When the testing of carriers is being considered, it is often not recognised that, in addition to individuals at a higher or lower risk of being a carrier, there are those who, on genetic grounds, must be carriers. Rare autosomal recessive disorders are the ones about which advice is most commonly sought, and family members may be greatly worried and alarmed by having been told they may be carriers. The common autosomal recessive disorders provide a much more important indication for carrier detection, although the disorders have to be extremely common to present a significant risk to individual couples. A relatively small number of X-linked recessive disorders provide the most important of all applications of carrier detection.
Genetics of Hearing Impairment
James R. Tysome, Rahul G. Kanegaonkar in Hearing, 2015
The identification of genes that contribute to hearing and balance is helping to elucidate the molecular biology of the inner ear. The disease genes causing sensorineural hearing impairment are expressed throughout the whole cochlea. The results of cochlear implantation are excellent in patients with both syndromic and non-syndromic genetic hearing impairment associated with profound hearing loss. Multiple technologies are available to identify the genetic defect underlying a clinically diagnosed hereditary hearing impairment. The pathomechanisms of hearing impairment depend on the mutated gene and, therefore, on the function of the encoded protein in the inner ear. Otogenetics will become more important in daily clinical practice, facilitating the diagnostic process for the hearing impaired patient and making accurate counselling of prognosis possible. The locus on the chromosome that harbours a gene involved in non-syndromic autosomal dominant hearing impairment is specified by the prefix ‘DFNA’.
The Usefulness of Sperm Viability Testing in Reproductive Technology: The Hypo-Osmotic Swelling Test, Laser and Motility Stimulants
Nicolás Garrido, Rocio Rivera in A Practical Guide to Sperm Analysis, 2017
It is commonly accepted that the standard World Health Organization (WHO) criteria for sperm number, motility, and morphology are a good, although not always perfect, indication of a male's fertility status. The current criteria have recently been changed from the 1999 to 2010 WHO recommendations, whereby semen volume, sperm concentration, progressive motility, and normal forms have all been decreased, respectively. This chapter discusses the various options that allow in vitro fertilization (IVF) clinics to improve the chances of success for couples in which the male has extremely poor sperm parameters that limit the chance of selection of a viable sperm. One test that is commonly used to assess viability is the hypo-osmotic swelling test (HOST), which acts because sperm with intact membranes are not leaky and will swell as they are able to retain fluid leading to coiling of the tail. Kartagener's syndrome belongs to a heterogeneous group of inherited autosomal recessive diseases.
A Dutch family with autosomal recessively inherited lower motor neuron predominant motor neuron disease due to optineurin mutations
Published in Amyotrophic Lateral Sclerosis and Frontotemporal Degeneration, 2015
Emma Beeldman, Anneke J. van der Kooi, Marianne de Visser, Merel C. van Maarle, Fred van Ruissen, Frank Baas
Approximately 10% of motor neuron disease (MND) patients report a familial predisposition for MND. Autosomal recessively inherited MND is less common and is most often caused by mutations in the superoxide dismutase 1 (SOD1) gene. In 2010, autosomal recessively inherited mutations in the optineurin (OPTN) gene were found in 1% of Japanese patients with sporadic amyotrophic lateral sclerosis (ALS). Autosomal dominantly inherited OPTN mutations have been described as a cause of primary open-angle glaucoma in the Netherlands and were also found in two Dutch sporadic MND patients. We report the first Dutch family with autosomal recessively inherited MND caused by mutations in the OPTN gene.
Genetic polymorphisms, forensic efficiency and phylogenetic analysis of 17 autosomal STR loci in the Han population of Wuxi, Eastern China
Published in Annals of Human Biology, 2019
Yan Lu, Hong-jie Sun, Ji-chuan Zhou, Xu Wu
The autosomal short tandem repeat (STR) plays a unique role in population comparisons, phylogenetic reconstruction and migration history tracing. This study investigated the frequencies of 17 autosomal STR loci in the Han population from Wuxi, Eastern China, with the aim of expanding the available population information in human genetic databases and for forensic DNA analysis. The genetic polymorphisms of 17 STR loci were analysed in 5358 individuals of the Han population from Wuxi, Eastern China. Population comparisons including genetic distances, the neighbour-joining tree and multidimensional scaling plot were carried out between the Wuxi Han population and different ethnic groups. A total of 777 alleles at 17 autosomal STR loci were observed, with the corresponding allelic frequencies ranging from 0.0001–0.5210. The combined power of discrimination and exclusion for the 17 autosomal STR loci were 0.0000 and 0.000, respectively. Moreover, the phylogenetic analysis was performed between the Wuxi Han population and other relevant populations. The neighbour-joining tree and multidimensional scaling plot were generated based on Nei’s standard genetic distance. Population comparisons indicated that the Wuxi Han population had the closest genetic relationship with the Hubei Han population, relative to the other populations, which mirrors the historical and geographical background of the populations compared.
Autosomal-dominant Leber Congenital Amaurosis Caused by a Heterozygous CRX Mutation in a Father and Son
Published in Ophthalmic Genetics, 2015
Karthikeyan Arcot Sadagopan, Robert Battista, Rosanne B. Keep, Jenina E. Capasso, Alex V. Levin
Background: Leber congenital amaurosis (LCA) is most often an autosomal recessive disorder. We report a father and son with autosomal dominant LCA due to a mutation in the CRX gene. Materials and Methods: DNA screening using an allele specific assay of 90 of the most common LCA-causing variations in the coding sequences of AIPL1, CEP290, CRB1, CRX, GUCY2D, RDH12 and RPE65 was performed on the father. Automated DNA sequencing of his son examining exon 3 of the CRX gene was subsequently performed. Results: Both father and son have a heterozygous single base pair deletion of an adenine at codon 153 in the coding sequence of the CRX gene resulting in a frameshift mutation. Conclusion: Mutations involving the CRX gene may demonstrate an autosomal dominant inheritance pattern for LCA.
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