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Pathophysiology of Sleep-Disordered Breathing in Children and Neonates
Published in Susmita Chowdhuri, M Safwan Badr, James A Rowley, Control of Breathing during Sleep, 2022
Sofia Konstantinopoulou, Ignacio E Tapia
PWS is a congenital disorder typified by hypothalamic obesity, developmental delay, hypotonia, and hypogonadism. The vast majority of patients have abnormalities of chromosome 15 (84). Although patients with PWS do not have classic central hypoventilation, they are included here as physiological testing has shown abnormalities of ventilatory control. OSAS and REM-associated desaturation are seen commonly. Patients tend to have restrictive lung disease based on obesity and muscle weakness (85), which can explain the tendency to desaturate. Excessive daytime sleepiness is common, and it has not been established whether this is due to SDB or also to a CNS component. Patients appear more predisposed to REM-onset sleep, although published studies have not excluded confounding factors such as sleep deprivation or partial upper airway obstruction (86). Physiological studies have shown blunted hypercapnic ventilatory responses secondary to obesity; patients in whom weight has been controlled have a normal hypercapnic drive. However, the ventilatory response to hypoxia (87), as well as other tests of peripheral chemoreceptor function, show a marked decrease in peripheral chemoreceptor function (88). A unifying hypothesis, therefore, is that the abnormalities of ventilatory control are due to the central processing of chemoreceptor input. Interestingly, a recent study shows that baseline ventilation and ventilatory drive increase following growth hormone administration, despite an unchanged body mass index (89).
Clinical genetics
Published in C. Simon Herrington, Muir's Textbook of Pathology, 2020
Imprinted genes are ones that are differentially expressed, depending on whether they are maternally or paternally inherited. Only certain genes in certain chromosomal regions are imprinted, e.g. only the maternally inherited copy of the UBE3A gene on chromosome 15 is active. If a child does not inherit a functioning copy from the mother then he or she will be affected with Angelman's syndrome. The gene could be inactivated by a point mutation or deletion, or an unusual transmission of chromosomes may occur, so that the child inherits two chromosomes 15 from its father but no chromosome 15 from its mother (paternal uniparental disomy).
Prader–Willi Syndrome: An Example of Genomic Imprinting
Published in Merlin G. Butler, F. John Meaney, Genetics of Developmental Disabilities, 2019
In 1989, molecular genetic methods and Southern hybridization of newly identified polymorphic DNA markers isolated from the 15q11–q13 chromosome region were reported by Nicholls et al. (14) in PWS individuals with normal appearing chromosomes and both chromosome 15s were from the mother. This phenomenon was termed maternal uniparental disomy 15 or UPD. Both members of the chromosome 15 pair were inherited from the mother as a result of nondisjunction or an error in the separation of the 15th chromosome pair in meiosis during egg production. One normal chromosome 15 was received from the father resulting in trisomy 15 (or three 15s) in the fetus. After fertilization, the father’s chromosome 15 is lost in the fetal cells during early pregnancy. If the trisomic 15 condition would have continued, a spontaneous miscarriage would have resulted. The loss of the father’s chromosome 15 in subsequent cells rescues the fetus. Chromosome abnormalities, specifically trisomy 15 and other trisomy and monosomy events, are common causes of spontaneous miscarriages. Approximately 50% of early miscarriages in the general population are due to chromosome problems.
Multifactorial influences on successful health outcomes for an adolescent with Prader-Willi syndrome: a qualitative case study
Published in Physiotherapy Theory and Practice, 2023
Nicole Campbell, Scott Van Zant, Joyce Lammers
Prader-Willi syndrome (PWS), a genetic, neurodevelopmental disorder affecting various body systems, is the most common syndromic cause of obesity (Eiholzer et al., 2000). The health complications associated with obesity are the leading cause of death in individuals with PWS (Dykens et al., 2007; Eiholzer et al., 2000; Einfield et al., 2006). It is a rare syndrome with an incidence of approximately 1 in 10,000–30,000, and a prevalence of 10,000 to 20,000 in the United States (Cassidy, Schwartz, Miller, and Driscoll, 2012). The syndrome is caused by an abnormality related to the expression of genes on chromosome 15; most commonly the result of a segmental deletion within the paternal chromosome (Butler et al., 2019). Currently, the PWS is diagnosed through genetic testing such as DNA-methylation testing to confirm the PWS diagnosis (Butler et al., 2002).
Nitric oxide pathway as a plausible therapeutic target in autism spectrum disorders
Published in Expert Opinion on Therapeutic Targets, 2022
Rishab Mehta, Anurag Kuhad, Ranjana Bhandari
The human leukocyte antigen (HLA) gene on chromosome 6 and killer cell immunoglobulin-like receptor (KIR) gene on chromosome 19 are reported to be associated with an enhanced risk of developing ASD [40]. A chromosome 15 phenotype has been identified having an altered sequence of the 15q11-15q13 region thus, causing cytogenetic abnormalities characterized by dysmorphic facial features, mental retardation, epilepsy, language delay, and repetitive movements [41,42]. The RELN gene found in the 7q22 region of chromosome 7 is suspected to be associated with neuronal migration and prenatal neuronal development [43]. The polymorphism of the MET gene found in 7q31 is known to affect the development of the cerebellum and cerebral cortex [44]. Various evidence-based studies suggest that disrupted MET signaling also leads to gastrointestinal dysfunction [45]. Alterations in chromosome 16 and chromosome 2 are also predicted to play a part in the occurrence of mental retardation, gastrointestinal alterations, and CNS disorders in patients with ASDs [6].
Improvement of Planning Abilities in Adults with Prader-Willi Syndrome: A Randomized Controlled Trial
Published in Developmental Neurorehabilitation, 2021
Séverine Estival, Virginie Laurier, Fabien Mourre, Virginie Postal
Prader-Willi Syndrome is a neurodevelopmental genetic disorder characterized by various expressions of endocrine, neurologic, cognitive and behavioral symptoms.1 The disorder is caused by the loss of expression of the imprinted genes from the 15q11q13 region of the paternal chromosome 15.2 Approximately 60% of cases are due to the deletion of the whole 15q11q13 region (type I deletion) or a part of it (type II deletion) and in 35% of cases, the entire 15th maternal chromosome is duplicated and the paternal chromosome is lost (uniparental maternal disomy).3 PWS is characterized by infantile hypotonia, mental retardation, feeding difficulty in infancy that evolves to an extreme drive to eat in childhood, dysmorphic features, short stature, hypogonadism, sleep apnea, diabetes, and severe maladaptive behaviors including obsessive, compulsive, and oppositional behaviors.4,5 Speech and language skills are also reported to be often impaired.6 Intellectual disability and deficit in executive functions are well documented in PWS: deficits in inhibition, switching, updating, cognition estimation, planning7–13 Executive functions (EF) are essential to allow a flexible and context-appropriate behavior when facing a new or complex situation.14,15 Planning is conceived as a higher cognitive function that implies the effective inhibition, updating and shifting processes.16