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Renal Cancer
Published in Karl H. Pang, Nadir I. Osman, James W.F. Catto, Christopher R. Chapple, Basic Urological Sciences, 2021
Sabrina H. Rossi, Grant D. Stewart
Genetics:Usually sporadic, but also includes familial syndromes associated with each type.Type 1Sporadic cases: gains (trisomy and tetrasomy) in chromosomes 7 and 17, and loss of chromosome Y in males.Hereditary cases: Hereditary papillary RCC syndrome (HPRCC). Mutations in the c-MET (Chm 7q) proto-oncogene (Table 23.3).Type 2Hereditary cases: Hereditary leiomyomatosis and RCC (HLRCC) syndrome. Mutations in the Fumurate Hydratase gene (Chm 1q) (Table 23.3).
Developmental Diseases of the Nervous System
Published in Philip B. Gorelick, Fernando D. Testai, Graeme J. Hankey, Joanna M. Wardlaw, Hankey's Clinical Neurology, 2020
James H. Tonsgard, Nikolas Mata-Machado
HI is believed to be due to a somatic cell mosaicism involving pigmentary genes. However, a variety of mosaic chromosomal abnormalities have also been reported including trisomy 18, triploidy, and tetrasomy 12p, and mutations in the X chromosome. It is hypothesized that the chromosomal anomalies disrupt expression or function of pigmentary genes. Pigmentary genes control a variety of processes, including melanoblast migration from the neural crest in fetal life. It is suggested that the pigmentary pattern that follows Blaschko's lines is the result of the migration of two different clones of cells during embryogenesis. The complex malformation of HI is postulated to be due to somatic genetic changes early in development, whereas patients with isolated skin manifestations are felt to be due to somatic changes in the skin alone, later in development. Mutations in the PI3K-AkT3-mTOR pathway have been seen in some patients.
Introductory Remarks
Published in Dongyou Liu, Handbook of Tumor Syndromes, 2020
Any failure to produce the standard number of chromosomes (44 autosomes and 2 sex chromosomes) is known as aneuploidy (see Chapter 46 for details), which typically appears as monosomy (lacking one chromosome), trisomy (having one extra chromosome; e.g., 47 XXX, 47 XXY, 47 XYY), tetrasomy (having two extra chromosomes; e.g., XXXX, XXYY), and pentasomy (having three extra chromosomes; e.g., XXXXX, XXXXY, XYYYY)] (see Chapter 2, Figure 2.4 for an exemplary karyotype associated with Klinefelter syndrome) [6].
Mosaic cat eye syndrome in a child with unilateral iris coloboma
Published in Ophthalmic Genetics, 2021
Cristina Hernández-Medrano, Alberto Hidalgo-Bravo, Cristina Villanueva-Mendoza, Teresa Bautista-Tirado, David Apam-Garduño
Cat eye syndrome is a chromosomal disorder with a classic triad of iris coloboma, anorectal malformations, and auricular abnormalities. CES is caused by the presence of additional genetic material derived from chromosome 22. It may be present as a partial tetrasomy or trisomy, or simultaneous duplication and inversion of chromosome 22. This anomaly usually appears sporadically and may occur during gametogenesis, mainly in oogenesis, or as an early post-zygotic event (8). The proximal portion of the long arm of chromosome 22 (22q11.2) is a critical region for chromosomal rearrangements due to its high content of low copy repeats (LCRs). LCRs are chromosome regions where recombination events can occur between homologous chromosomes during meiosis. The mechanism leading to rearrangements is unclear, but the model of the U-type interchromosomal exchange has been postulated (8), where homologous chromosomes are misaligned due to the high LCR content. This misalignment and genomic crosslinking lead to segregation errors and non-allelic homologous recombination during cell division (1,2,8).
Sleep Problems and Life Satisfaction as Predictors of Health in Men with Sex Chromosome Aneuploidies
Published in Behavioral Medicine, 2018
Krister W. Fjermestad, Simen Stokke
In terms of physiology, hypogonadism (i.e., low testosterone levels) is prevalent for conditions with supernumerary X chromosomes, occurring in up to 85% of postpubertal men with 47,XXY.7 Hypogonadism often causes low testicular volume and high rates of infertility as well as sparse body hair growth. In terms of cognitive functioning, full-scale IQ scores are generally within the normal range for karyotypes 47,XXY and 47,XYY with considerable individual variation.8 IQ tends to be lower and in the borderline to mild mental retardation range for the tetrasomy conditions.9,10 Significantly lower verbal IQ relative to performance IQ has been found across karyotypes.10 Relative to controls, specific cognitive challenges, which have been identified more frequently among men with SCA, include receptive and expressive language abilities as well as short-term and verbal memory, attention, and executive functions.4,11,12 Increased prevalence of reading and writing difficulties for men with SCA is likely to be a result of the language problems.13–15 In terms of psychological functioning, men with SCA have increased risk of experiencing general psychological distress, as well as higher prevalence rates of depression, anxiety, attention deficit hyperactivity disorder, autism spectrum disorder, and schizophrenia.6
Clinical genomics and contextualizing genome variation in the diagnostic laboratory
Published in Expert Review of Molecular Diagnostics, 2020
James R. Lupski, Pengfei Liu, Pawel Stankiewicz, Claudia M. B. Carvalho, Jennifer E. Posey
It is interesting to speculate about specific chromosome 21 gene dosage effects and clinical findings and phenotypes that can be observed in patients with Down syndrome: APP duplication [4,5] and early-onset dementia, and an oncogene mapping to chromosome 21 and increased risk of leukemia. Or perhaps leukemia observed in a child with tetrasomy 21 [6,7]. It is also interesting to consider whether other well-known clinical observations for Down syndrome, implicate a potential dosage-sensitive gene(s) or locus mapping to chromosome 21.