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Molecular Biology and Gene Therapy
Published in R James A England, Eamon Shamil, Rajeev Mathew, Manohar Bance, Pavol Surda, Jemy Jose, Omar Hilmi, Adam J Donne, Scott-Brown's Essential Otorhinolaryngology, 2022
A gene is a region of the chromosomal DNA that produces a functional ribonucleic acid molecule (RNA). It comprises regulatory DNA sequences that determine when and in which cell types that gene is expressed; exons are coding sequences and interspersed introns are non-coding DNA sequences.
Cancer Biology and Genetics for Non-Biologists
Published in Trevor F. Cox, Medical Statistics for Cancer Studies, 2022
Cancer is not one disease but a collection of diseases. It occurs when the DNA of a cell is damaged, and as there are about 200 different types of cells in the body, there can be 200 types of cancer. DNA damage is caused by mutations (changes) of the genetic code. The mutation can affect a single gene or, more widely, a chromosome.
Causes and risk factors
Published in Janetta Bensouilah, Pregnancy Loss, 2021
Chromosomal abnormalities are the most frequent cause of early, spontaneous, isolated miscarriages, but in cases of RM they are a less frequent cause, affecting around 2–4% of cases.3 Chromosomes are strands of genetic material that contain the genetic code which makes up an individual. A human being has 46 chromosomes in every cell, 23 chromosomes being inherited from each parent. Before conception, the chromosomes of the egg and sperm cells first divide, a process known as meiosis, so that each has only 23 chromosomes. Subsequently, at fertilisation, the normal chromosome number of 46 is restored as a result of the fusion of sperm and egg. Around 12–24 hours after fertilisation, a complex process of vigorous cell division and multiplication, known as mitosis, begins. At this stage some chromosomes may be lost or damaged, and if one of the chromosomes is abnormal, or an incorrect number of chromosomes is left in the fertilised egg, an abnormal fetus may develop. The vast majority of such abnormalities are incompatible with life and will miscarry at an early stage, although some will continue to birth and may or may not survive.
A bibliometric analysis of primary ovarian insufficiency from 2010 to 2020
Published in Climacteric, 2022
Z.-H. Deng, H.-J. Tan, L. Wang, P.-P. Long, D. Guo, R.-P. Quan, M.-H. Zeng, H.-W. Deng, H.-M. Xiao
Mutation in the FMR1 gene is associated with Fragile X syndrome, in which patients are more likely to suffer from POI. Turner syndrome is a rare condition in women that is associated with either complete or partial loss of one X chromosome. Typical clinical manifestations include ovarian dysgenesis, hypogonadotropic hypogonadism and infertility [20]. In addition to cancer patients, fertility preservation techniques may also be used in patients with Turner syndrome and Fragile X syndrome. Unfortunately, most of the data on fertility preservation available in the literature concern cancer patients while patients with syndromic POI present a particular complexity due to other co-presence symptoms. Fertility preservation in these patients should be treated accurately and individually [21].
Differences in foot dimensions between children and adolescents with and without Down syndrome
Published in Disability and Rehabilitation, 2022
Nirmeen M. Hassan, Andrew K. Buldt, Nora Shields, Karl B. Landorf, Hylton B. Menz, Shannon E. Munteanu
Down syndrome is a common chromosomal abnormality that results in the trisomy of chromosome 21 [1]. It is associated with a number of orthopaedic anomalies and musculoskeletal disorders [2]. Approximately 20 to 27% of people with Down syndrome experience musculoskeletal disorders, and foot deformities make up 30% of all reported orthopaedic complaints [3]. Structural anomalies such as hallux valgus deformity and flat feet are the two most commonly reported in the literature [4–6]. However, other structural anomalies that may cause foot problems include digital deformities, bony deformities of the forefoot [4], hallucal cleft, isolated calcaneal valgus [4] and a plantarflexed first ray. Several of these structural anomalies are thought to occur secondary to higher body mass index [7], muscular hypotonia [8], ankle instability [9] as well as ligamentous laxity [10] – all of which are associated with Down syndrome. These structural anomalies may have a negative impact on gait, engaging in daily activities [11] and footwear-fitting.
Do parent-mediated interventions improve communication and language development in children with Down syndrome? – A Cochrane Review summary with commentary
Published in Developmental Neurorehabilitation, 2020
Down syndrome is a genetic disorder caused by the presence of all or part of a third copy of chromosome 21; the incidence of Down syndrome has been estimated to range from 1 per 1000 to 1100 live births worldwide.2 It is the most common genetic cause of intellectual disability, and is associated with abnormalities in various organ systems and developmental difficulties, such as congenital heart disease and hearing and vision disorders. Language is especially impaired and contributes to difficulties in achieving independent living.3 Children with Down syndrome generally present a language profile characterized by poorer expressive than receptive skills, particularly in terms of vocabulary, and difficulties with both receptive and expressive grammar.4 Interactions with caregivers have been shown to have a beneficial impact on a child’s language development.5 Thus, for young children with Down syndrome, it is thought that training their parents on the importance of the quality and quantity of their language input, interaction, and responsivity could promote language development in these children. Parent-mediated interventions are designed to foster and increase adult–child interactions and facilitate adequate language modeling and prompting from adult in an ecologically valid and family-centered way.6 A Cochrane Review synthetized evidence regarding the effects of parent-mediated interventions on communication and language development in children with Down syndrome.1