Multiple Aneuploidy: First Report of a Patient Presenting with a Karyotype 45,X/48,XXX,+21.

INTRODUCTION: The dual diagnosis of Down syndrome and Turner syndrome in the same patient was clinically identified in the early 1950s before the development of karyotyping techniques. After that, several authors reported anecdotal patients and/or reviewed series of Down-Turner double aneuploidies due to a regular 46,X,+21 constitution or different combinations of abnormal cell lines. In such cases, the most typical presentation encompasses the female sex, Down syndrome phenotype, and chromosomal mosaicism. CASE PRESENTATION: Here we report a female patient presenting with short stature, dysmorphic features, developmental delay, and learning disabilities, whose karyotype revealed a previously undescribed 45,X[47]/48,XXX,+21[3] constitution. CONCLUSION: This is the first case encompassing these three aneuploidies together and, contrary to most previous reports, exhibiting a predominantly Turner syndrome phenotype associated with developmental delay.

Loss of the Y Chromosome: A Review of Molecular Mechanisms, Age Inference, and Implications for Men's Health.

Until a few years ago, it was believed that the gradual mosaic loss of the Y chromosome (mLOY) was a normal age-related process. However, it is now known that mLOY is associated with a wide variety of pathologies in men, such as cardiovascular diseases, neurodegenerative disorders, and many types of cancer. Nevertheless, the mechanisms that generate mLOY in men have not been studied so far. This task is of great importance because it will allow focusing on possible methods of prophylaxis or therapy for diseases associated with mLOY. On the other hand, it would allow better understanding of mLOY as a possible marker for inferring the age of male samples in cases of human identification. Due to the above, in this work, a comprehensive review of the literature was conducted, presenting the most relevant information on the possible molecular mechanisms by which mLOY is generated, as well as its implications for men's health and its possible use as a marker to infer age.

To transfer or not to transfer: the dilemma of mosaic embryos - a narrative review.

A frequent finding after preimplantation genetic diagnostic testing for aneuploidies using next-generation sequencing is an embryo that is putatively mosaic. The prevalence of this outcome remains unclear and varies with technical and external factors. Mosaic embryos can be classified by the percentage of cells affected, type of chromosome involvement (whole or segmental), number of affected chromosomes or affected cell type (inner mass cell, trophectoderm or both). The origin of mosaicism seems to be intrinsic as a post-zygotic mitotic error, but some external factors can play a role. As experience has increased with the transfer of mosaic embryos, clinical practice has gradually become more flexible in recent years. Nevertheless, clinical results show lower implantation, pregnancy and clinical pregnancy rates and higher miscarriage rates with mosaic embryo transfer when compared with the transfer of euploid embryos. Prenatal diagnosis is highly recommended after the transfer of mosaic embryos. This narrative review is intended to serve as reference material for practitioners in reproductive medicine who must manage a mosaic embryo result after preimplantation genetic testing for aneuploidies.

RET 634 germline/gonadal mosaicism generating a second pathogenic amino acid change in multiple endocrine neoplasia type 2A.

Genetic testing for germline RET pathogenic variants, which cause the Multiple Endocrine Neoplasia Type 2 (MEN2) syndrome, has become crucial in managing patients with medullary thyroid carcinoma (MTC). Classically, RET heterozygous missense pathogenic variants are transmitted in a Mendelian autosomal dominant pattern, of which germline/gonadal mosaicism has never been reported. We report the novel occurrence of a MEN2A patient's family in which the siblings inherited three different RET 634 genotypes: wild type (p.Cys634), p.Cys634Gly or p.Cys634Arg heterozygous pathogenic variants. We hypothesized that germline/gonadal mosaicism, derived from an inherited + early somatic mutation in the mother or a double de novo mutation during maternal embryogenesis, led to this rare event in the RET gene. Exome analysis of the proband's deceased mother's paraffin-embedded thyroid tissue confirmed the three nucleotides in the same 634 codon position. For the first time, we describe germline/gonadal mosaicism in RET, generating a second pathogenic amino acid change in the same codon causing MEN2A. Our finding shows that RET parental mosaicism, confirmed by somatic exome sequencing, might explain discrepant genotype cases in siblings with inherited cancers.

Occurrence of mosaic trisomy 22 and pericentric inversion of chromosome 9 in a patient with a good prognosis.

Complete trisomy 22 is a rare chromosomal condition that is incompatible with life. However, mosaic trisomy 22 usually has prolonged survival compatibility and may present a good prognosis depending on the tissues affected. Herein, we described a male patient with the occurrence of mosaic trisomy 22 associated with the inversion of chromosome 9, with karyotype 47, XY, inv (9) (p11q13), + 22 [5] / 46, XY, inv(9) (p11q13) [45] and arr 22q11.1 ~ q13.33(16,417008-51,219,009)x2 ~ 3. It is not possible to infer, in general, the clinical characteristics associated with mosaic trisomy 22. However, the patient presented common clinical features observed in reported cases (in parentheses the percentage observed comparing all reported cases): facial dysmorphia (100%), delay in motor development/growth (82%), cardiac abnormalities (73%), ear abnormalities (55%) and facial and/or body asymmetry (55%), in addition to hypotonia, skin spots, hypoplastic nails. Given the survival and quality of life associated with multidisciplinary treatment, it can be concluded that the patient has a good prognosis. Conclusively, we're presenting the occurrence of mosaic trisomy 22 and chromosome 9 inversion in the patient with favorable prognosis. Thus, this study proposed a guide which should be inserted in databases of rare genetic conditions to help genetic counselors define mosaic trisomy 22 diagnosis.

Identification of a Small Supernumerary Marker Chromosome in a Turner Syndrome Patient with Karyotype mos 46,X,+mar/45,X.

Turner Syndrome is characterized by a normal X chromosome and the partial or complete absence of a second sexual chromosome. Small supernumerary marker chromosomes are present in 6.6% of these patients. Because of the wide range of Turner syndrome karyotypes, it is difficult to establish a relationship with the phenotype of the patients. We present the case of a female patient with Turner syndrome, insulin resistance, type 2 diabetes, and intellectual disability. The karyotype revealed the presence of mosaicism with a monosomy X cell line and a second line with a small marker chromosome. FISH of two different tissues was used to identify the marker chromosome with probes for X and Y centromeres. Both tissues presented mosaicism for a two X chromosome signal, differing in the percentage of the monosomy X cell percentage. Comparative genomic hybridization with the CytoScanTMHD assay was performed in genomic DNA from peripheral blood, allowing us to determine the size and breakage points of the small marker chromosome. The patient presents a phenotype that combines classic Turner syndrome features and unlikely ones as intellectual disability. The size, implicated genes, and degree of inactivation of the X chromosome influence the broad spectrum of phenotypes resulting from these chromosomes.

Experimental approaches to assess melanocytes mosaicism in segmental vitiligo.

Vitiligo is an autoimmune disease of the skin that results in localized or disseminated white macules. One common feature of several existing classification protocols is the distribution of the disease into two main subtypes, non-segmental vitiligo (NSV) and segmental vitiligo (SV). SV is characterized by depigmentation spreading within one or more skin segments while NSV is widespread. Several clinical-epidemiological observations suggest that SV has distinct autoimmune pathophysiology compared to NSV. Furthermore, the clinical distribution pattern of SV lesions closely resembles other melanocyte mosaicism diseases. These observations led us to hypothesize that SV is caused by a localized autoimmune reaction targeting epidermal mosaicism melanocytes. Here, we proposed examples of experimental approaches to assess mosaicism in SV patients.

SOX3 duplication in a boy with 46,XX ovotesticular disorder of sex development and his 46,XX sister with atypical genitalia: Probable germline mosaicism.

Ovotesticular disorders of sex development (OT-DSD) are characterized by ovarian follicles and seminiferous tubules in the same individual, with a wide range of atypical genitalia. We report on two sibs with atypical genitalia and SRY-negative 46,XX DSD, OT-DSD was confirmed only in the boy, while the girl had bilateral ovaries. Chromosome microarray analysis (CMA) showed a 737-kb duplication at Xq27.1 including the entire SOX3 gene in both sibs, which was confirmed by quantitative real time PCR. Also, X chromosome inactivation assay showed random inactivation in both sibs. Whole exome sequencing revealed no pathogenic or likely pathogenic variant. CMA of the parents showed normal results for both, suggesting that germline mosaicism could be the reason of recurrence of this duplication in the siblings. Our results support a pathogenic role of SOX3 overexpression in 46,XX subjects leading to variable DSD phenotypes.

Turner syndrome associated with Down syndrome: about a case / Síndrome Turner asociado a síndrome Down: a propósito de un caso

The coexistence of double aneuploidy of Down and Turner syndromes is rare; most cases have been due to double mitotic errors. The objective of the study was to report a case with monosomy of the X chromosome and trisomy of chromosome 21, in mosaic variety, highlighting the phenotypic effect that the presence of different chromosomal abnormalities can produce and compare with those reported in the literature. A 10-year-old Ecuadorian female, born to a multipregnant mother with 46 years at conception, is seen in consultation with a predominant clinical phenotype of Down syndrome, associated with menarche, presence of pubic and axillary villu, where a karyotype is verified 45 X[7]/47XX+ 21 [3]/46, X, der (X)(: p11.1-> q11.1)[1]/46,XX [1]. The present case is a double Turner-Down aneuploidy, with predominantly X monosomy cell line, who shows important mental retardation and some signs of puberal development not usually in Turner syndrome. These features highlight the clinical importance of doing a karyotype in mental retardation cases and searching low mosaics of another aneuploidies in atypical cases. Its complex chromosomal formula and support with molecular cytogenetics allowed diagnostic confirmation and genetic counseling.

La coexistencia de doble aneuploidía de los síndromes de Down y Turner es rara; la mayoría de los casos se han debido a dobles errores mitóticos. Reportar un caso con trisomía del cromosoma 21 y monosomía del cromosoma en X, en variedad mosaico, que curiosamente presenta un despertar puberal precoz y comparar con los reportados en la literatura. Paciente ecuatoriana de sexo femenino, de 10 años de edad, nacida de madre multigesta con 46 años a la concepción, que es vista en consulta con fenotipo clínico predominante de Síndrome Down, asociado a menarquia y telarquia, donde se constata un cariotipo. El presente caso es el primero informado de mosaicismo de doble aneuploidía de Turner-Down asociado con un despertar puberal precoz. Su fórmula cromosómica compleja y el apoyo con la citogenética molecular permitió la confirmación diagnostica y la asesoría genética.

Cellular consequences of small supernumerary marker chromosome derived from chromosome 12: mosaicism in daughter and father.

Constitutional genomic imbalances are known to cause malformations, disabilities, neurodevelopmental delay, and dysmorphia and can lead to dysfunctions in the cell cycle. In extremely rare genetic conditions such as small supernumerary marker chromosomes (sSMC), it is important to understand the cellular consequences of this extra marker, as well the factors that contribute to their maintenance or elimination through successive cell cycles and phenotypic impact. The study of chromosomal mosaicism provides a natural model to characterize the effect of aneuploidy on genome stability and compare cells with the same genetic background and environment exposure, but differing in the presence of sSMC. Here, we report the functional characterization of different cell lines from two familial patients with mosaic sSMC derived from chromosome 12. We performed studies of proliferation dynamics, stability, and variability of these cells using fluorescent in situ hybridization (FISH), sister chromatid exchanges (SCE), and conventional staining. We also quantified the telomere-related genomic instability of sSMC cells using 3D telomeric profile analysis by quantitative-FISH. sSMC cells exhibited differences in the cell cycle dynamics compared to normal cells. First, the sSMC cells exhibited lower proliferation index and higher frequency of SCE than normal cells, associated with a higher level of chromosomal instability. Second, sSMC cells exhibited more telomeric-related genomic instability. Lastly, the differences of sSMC cells distribution among tissues could explain different phenotypic repercussions observed in patients. These results will help in our understanding of the sSMC stability, maintenance during cell cycle, and the cell cycle variables involved in the different phenotypic manifestations.

Dynamic epigenetic age mosaicism in the human atherosclerotic artery.

Accelerated epigenetic ageing, a promising marker of disease risk, has been detected in peripheral blood cells of atherosclerotic patients, but evidence in the vascular wall is lacking. Understanding the trends of epigenetic ageing in the atheroma may provide insights into mechanisms of atherogenesis or identify targets for molecular therapy. We surveyed DNA methylation age in two human artery samples: a set of donor-matched, paired atherosclerotic and healthy aortic portions, and a set of carotid artery atheromas. The well-characterized pan-tissue Horvath epigenetic clock was used, together with the Weidner whole-blood-specific clock as validation. For the first time, we document dynamic DNA methylation age mosaicism of the vascular wall that is atherosclerosis-related, switches from acceleration to deceleration with chronological ageing, and is consistent in human aorta and carotid atheroma. At CpG level, the Horvath epigenetic clock showed modest differential methylation between atherosclerotic and healthy aortic portions, weak association with atheroma histological grade and no clear evidence for participation in atherosclerosis-related cellular pathways. Our data suggest caution when assigning a unidirectional DNA methylation age change to the atherosclerotic arterial wall. Also, the results support previous conclusions that epigenetic ageing reflects non-disease-specific cellular alterations.

Somatic mosaicism in patients with Fanconi anaemia: Proposal of alternative tissue for inconclusive diagnoses.

INTRODUCTION: Fanconi anaemia (FA) is a rare genetic disorder marked by progressive bone marrow failure, chromosomal fragility, and increased cancer susceptibility. Laboratory diagnosis includes chromosomal instability test and mutation investigation. A total of 15%-25% of all patients may have somatic mosaicism, characterized by two distinct haematopoietic cell populations, one resistant and one sensitive to agents that induce chromosomal breakage, which complicates the diagnosis by a high incidence of reverted cells leading to inconclusive or false-negative results. The study aimed to evaluate the use of bone marrow stromal mesenchymal cells (BM-MSCs) as an alternative, non-haematopoietic tissue for diagnosis. METHODS: Bone marrow mesenchymal stromal cells from 12 patients with positive diepoxybutane (DEB) tests were cultivated and analysed by cytogenetics and mutation investigation. RESULTS: The DEB test was performed at 0.1 and 0.01 µg/ml concentrations, with an index ranging from 0.24 to 1.00. At higher concentration, the metaphases number was lower, probably due to toxicity. Regarding the molecular investigation, all the mutations previously found in peripheral blood were identified on BM-MSC. CONCLUSION: This study demonstrated the possibility of using BM-MSCs as an alternative tissue for cytogenetic and molecular investigation. Future tests using an intermediate DEB concentration may lead to an optimal protocol that could be non-toxic to cells but provides conclusive results.

45,X/46,XY Mosaicism with Male Phenotype: Case Report.

Mixed gonadal dysgenesis is the most common chromosomal abnormality with ambiguous genitalia, defined as a 45,X/46,XY mosaicism. It can present with a normal male phenotype, ambiguous genitalia, or features of Turner syndrome. A 14-year-old patient was referred to the genetics clinic due to hypospadia, cryptorchidism, and aortic coarctation. During the physical examination, short stature, webbed neck, and Blashko lines on his back were noted. He had a previous karyotype reported as normal. However, due to an inadequate evolution and a low resolution on the previous test, a higher resolution karyotype was performed, identifying a mosaicism 45,X/46,XY. A multidisciplinary board examined the case, and follow-up with tumor markers was carried out to evaluate the presence of gonadoblastoma, one of the main complications in these patients. Treatment should be transdisciplinary and focused on the particular characteristics of each case. Other treatment alternatives include corrective surgery and hormonal therapy.

Mosaicism in Fragile X syndrome: A family case series.

Fragile X syndrome (FXS) has a classic phenotype, however its expression can be variable among full mutation males. This is secondary to variable methylation mosaicisms and the number of CGG triplet repeats in the non-coding region of the Fragile X Mental Retardation 1 (FMR1) gene, producing a variable expression of the Fragile X Mental Retardation Protein (FMRP). Here we report a family with several individuals affected by FXS: a boy with a hypermethylated FMR1 mutation and a classic phenotype; a man with an FMR1 gene mosaicism in the range of premutation (PM) and full mutation (FM), who has a mild phenotype due to which FXS was initially disregarded; and the cases of four women with a FM and mosaicism. This report highlights the importance of DNA molecular testing for the diagnosis of FXS in patients with developmental delay, intellectual disability and/or autism due to the variable phenotype that occurs in individuals with FMR1 mosaicisms.

Searching chromosome mosaicisms in 45, X Turner syndrome: how relevant is it?

ABSTRACT Objective: To investigate the presence of chromosome mosaicism, especially for the presence of Y derived material in 45,X women with Turner syndrome (TS). Materials and methods: FISH and PCR were performed for the presence of chromosome mosaicism and Y-derived-material and genetic findings were correlated to clinical data. Results: Thirty-one participants were enrolled: 18 (58%) had chromosome mosaicisms (FISH), Y-derived material was found in 2. Yet, SRY primer was found with PCR in only one of them and DYZ3 was not found. The most frequent clinical findings were short or webbed neck (81,82%), high-arched palate (78%), breast hypertelorism, e cubitus valgus and genu valgus (57.6%, both), short fourth metacarpals (46.9%), epicanthic folds (43.8%), shield chest (43.8%), lymphedema (37.5%), and low set ears (34.4%). Both patients with Y-derived-material had primary amenorrhea, dyslipidemia and reached the height of 150 cm despite not treated with recombinant growth hormone (GHr). One of them showed 26% of leukocytes with Y-derived material and few clinical findings. Conclusions: FISH techniques proved efficient in detecting chromosome mosaicisms and Y-derived material and searching in different tissues such as mouth cells is critical due to the possibility of tissue-specific mosaicism. Phenotypical variance in TS may be a signal of chromosome mosaicisms, especially with the presence of Y-derived material.

Searching chromosome mosaicisms in 45,X Turner syndrome: how relevant is it?

OBJECTIVE: To investigate the presence of chromosome mosaicism, especially for the presence of Y derived material in 45,X women with Turner syndrome (TS). METHODS: FISH and PCR were performed for the presence of chromosome mosaicism and Y-derived-material and genetic findings were correlated to clinical data. RESULTS: Thirty-one participants were enrolled: 18 (58%) had chromosome mosaicisms (FISH), Y-derived material was found in 2. Yet, SRY primer was found with PCR in only one of them and DYZ3 was not found. The most frequent clinical findings were short or webbed neck (81,82%), high-arched palate (78%), breast hypertelorism, e cubitus valgus and genu valgus (57.6%, both), short fourth metacarpals (46.9%), epicanthic folds (43.8%), shield chest (43.8%), lymphedema (37.5%), and low set ears (34.4%). Both patients with Y-derived-material had primary amenorrhea, dyslipidemia and reached the height of 150 cm despite not treated with recombinant growth hormone (GHr). One of them showed 26% of leukocytes with Y-derived material and few clinical findings. CONCLUSION: FISH techniques proved efficient in detecting chromosome mosaicisms and Y-derived material and searching in different tissues such as mouth cells is critical due to the possibility of tissue-specific mosaicism. Phenotypical variance in TS may be a signal of chromosome mosaicisms, especially with the presence of Y-derived material.

Segmental Cervical Aplasia in a Colombian Creole Mare with Mosaic X-Chromosome Aneuploidy.

A 4-year-old Colombian Creole mare was presented for diagnosis because the external orifice of her cervix was not detectable when a uterine lavage as therapy for uterine fluid accumulation was attempted. Clinical and ultrasonographic evaluation of the genital tract revealed that ovaries were of normal size and showed structures suggestive of regular ovarian activity. However, granular free-floating fluid material distending the uterus was detected by ultrasound. Upon vaginal examination, the normal external cervical morphology was not evident. The vagina ended in a blind bag with a small papilla with no evident external cervical os. Cytology of uterine fluid obtained by transvaginal aspiration showed findings compatible with mucometra. Cytogenetic analysis revealed an abnormal karyotype (63,X and 64,XX both 45% and 65,XXX 10%). A diagnosis of congenital segmental cervical aplasia was proposed possibly related to the mosaicism detected. To our knowledge, this is the first case of this reproductive pathology in a mare with regular ovarian activity and confirmed aneuploidy in mosaic form of the X sex chromosome.

Spontaneous Pubertal Onset in a Male Patient With Mixed Gonadal Dysgenesis With Mosaicism 45,X/ 46, X, mar (Y)/ 47,X,mar(Y),+mar(Y) - Pediatric Case Report.

This report describes an adolescent with Mixed Gonadal Dysgenesis and unexpected mosaicism [karyotype 46,X,mar(Y)/ 47,X, mar(Y),+mar(Y)].). Diagnosis with 1 month of age due to atypical genitalia. He presented a right streak gonad, which was removed due to the risk for germ cell tumor, and a left testis with epididymis barely connected and without vas deferens. Left testis maintenance was sufficient for him to undergo spontaneous puberty. The patient was non-responsive to growth hormone. Webbed neck was the only dysmorphic feature. To the best of our knowledge, there were no similar cases reported with spontaneous pubertal progress reported in the literature.