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Chromosome abnormalities
Published in Angus Clarke, Alex Murray, Julian Sampson, Harper's Practical Genetic Counselling, 2019
Chromosome disorders are relatively common as the cause of serious childhood malformations and rank high in the requests for genetic counselling, but before describing the risks in specific groups, there are three points worthy of mention that the clinician and genetic counsellor should bear in mind from the outset: The great majority of disorders following Mendelian inheritance, especially those of adult life, show no visible chromosomal abnormality.The great majority of chromosomal disorders have a low risk of recurrence in a family, especially where no abnormality (including a balanced carrier state) is present in either parent.Some chromosome rearrangements will be detected more readily on a karyotype than by array comparative genomic hybridisation (CGH).
Variation of sex differentiation
Published in Joseph S. Sanfilippo, Eduardo Lara-Torre, Veronica Gomez-Lobo, Sanfilippo's Textbook of Pediatric and Adolescent GynecologySecond Edition, 2019
Anne-Marie Amies Oelschlager, Margarett Shnorhavorian
Classification of DSD conditions is based on underlying karyotype, including 46,XX DSD; 46,XY DSD; and sex chromosome DSD. In general, ambiguous genitalia in infancy with 46,XX DSD conditions are due to excess virilization, and 46,XY DSD conditions are due to undervirilization. Sex chromosome disorders include gonadal dysgenesis; Turner syndrome (45,X); mixed gonadal dysgenesis (45,X/46,XY); Klinefelter's syndrome and variants (47,XXY); and ovotesticular DSD (45,X/46,XY or 46,XX/46,XY). Additional genetic etiologies include mosaicism and chimerism. The causes of DSD can be broadly categorized as sex steroid excess or deficiency due to a central or peripheral etiology, hormonal receptor deficiencies, or atypical or slowed migration of the Müllerian or wolffian ducts (Tables 7.2 and 7.3).
Pre- and Perinatal Factors in the Etiology of Mental Retardation
Published in Michele Kiely, Reproductive and Perinatal Epidemiology, 2019
In pure primary disorders, an autosome or sex chromosome aberration in a gamete produces an abnormal chromosome constitution in the zygote, which is present at conception. Down’s Syndrome, Trisomy 21, is the archetype and by far the most numerous. Other autosomal anomalies include Trisomy 13 (Patau’s Syndrome), and Trisomy 17 or 18 (Edward’s Syndrome), and many more even rarer. Sex chromosome disorders are mostly Klinefelter’s and Turner’s Syndromes, and are only occasionally associated with significant intellectual impairment. X-linked disorders are now more prominent, with fragile X syndrome dominating. There also seem to be some nonspecific recessive disorders leading to low intelligence. A few clearly defined syndromes, such as De Lange Syndrome and severe hypercalcemia syndrome are probably, but not yet certainly primary.
Prenatal diagnosis of trisomy 22 at the first trimester of pregnancy
Published in Journal of Obstetrics and Gynaecology, 2020
Bi-Qiu Xu, Xiao-Cui Jiang, Li Wan, Sha Wang, Yan-Dong Yang, Dong-Zhi Li
Considering the extremly low level of PAPP-A and a very high risk for common trisomy, the patient was given an early in-depth investigation of the foetal morphology by a systematic visualisation of the anatomy. This detected a suspected isolated cleft palate and double outlet right ventricle (Figure 1(A,B)). The patient was counselled again, and she decided to undergo chorionic villus sampling for foetal chromosome analysis. Quantitative fluorescent polymerase chain reaction (QF-PCR) excluded trisomies 21, 18, 13, or sex chromosome disorders, but karyotype analysis by cultured chorionic villi diagnosed 47, XX,+22 in 20 analysed metaphases cells (Figure 1(C)), which can be considered a complete trisomy 22. Parental karyotyping analysis was performed and it was normal. The pregnancy was terminated at 15 weeks of gestation. A physical examination confirmed the cleft right lip and palate. A post-mortem examination was denied. The amniocentesis at termination showed there was a 47, XX,+22 karyotype in 30 analysed metaphases cells.
Premature ovarian failure, short stature, and Hashimoto’s disease in an 18-year-old adolescent girl with 46, X, i(X)(q10)
Published in Gynecological Endocrinology, 2018
Xiang Hu, Qiao Zhang, Feng Gao, Lu-Lu Chen
46, X, i(X)(q10) is an extremely rare X chromosome abnormality and has been reported in a patients as a cause of Duchenne muscular dystrophy [4] and in a fetus expected to have many of the characteristics of Turner syndrome, who died in utero at 18 weeks’ gestation [5], suggesting that 46, X, i(X)(q10) karyotype is clinically heterogeneous especially in phenotype. To the best of our knowledge, this is the first identification of 46, X, i(X)(q10) in an adolescent girl with POF, short stature, and Hashimoto’s disease, without classical and typical phenotype of Turner syndrome or Duchenne muscular dystrophy [6], although her stature was short and interorbital width seemed a little bit wider. These symptoms are different from those in the cases with the same karyotype but characterized by Duchenne muscular dystrophy [4] or typical Turner syndrome [5]. It is reported that POF can be caused by chromosome X aberrations including the extra X chromosome(s) [7] or mosaic forms of chromosome X abnormalities [3,8]. Here we demonstrated that 46, X, i(X)(q10) also can cause POF. Note of worthy, POF and short stature appear in Turner-like syndrome [9]. Thus, it is difficult to assume it was non-typical Turner syndrome or not in this case. Moreover, ovarian and thyroid gland abnormalities were involved, and X chromosome disorders are considered to be causes of autoimmune polyglandular syndrome [10]. Thus, consideration of a new or non-typical autoimmune polyglandular syndrome also should be involved.
Sex chromosome changes in leukemia: cytogenetics and molecular aspects
Published in Hematology, 2018
Saeid Shahrabi, Elahe Khodadi, Fakhredin Saba, Mohammad Shahjahani, Najmaldin Saki
Klinefelter syndrome (KS) with the classic form of 47, XXY is the most common sex chromosome disorder in men. However, the increase in sex chromosomes, including an increase in the X chromosome (over 4 chromosomes) and in the Y chromosome (over 2 chromosomes) as well as the mosaic form of 47, XXY/46, XY, has also been reported. KS is rarely associated with CML [60–62]. In these patients, SCL occurs during the formation of abnormal karyotype, which leads to three different clones: 46, XX, -Y, t(9; 22)(q34; q11)/46, XX, t(Y; 20) (q11; q13), t (9; 22)(q34; q11), -der(Y) t(Y; 20) (q11; q13)/near-tetraploid (4n). Some studies confirm the association between the Y chromosome disorders in KS patients and CML in the formation of malignant clones with t(9,22) chromosomal abnormality [7]. However, when LOY is, for the first time, observed in a patient referred for cytogenetic analysis, there is a big challenge in determining the prognosis and clinical course of the disease [8].