A Case Report of a Rare 46,XX/47,XXY Mosaicism With Ovotesticular Disorder of Sex Development and a Literature Review.

Klinefelter syndrome (KS) is a common chromosomal abnormality in males, usually presenting as a 47,XXY karyotype and often underdiagnosed. Rarely, KS occurs as mosaic 46,XX/47,XXY. At the same time, ovotesticular disorder of sex development (OT-DSD) is also a rare condition in which both ovarian and testicular structures are present in the same individual, often associated with a 46,XX karyotype. The combination of mosaic 46,XX/47,XXY with OT-DSD is scarce. Herein, we report a new case of a six-month-old infant with unilateral OT-DSD and a 46,XX/47,XXY mosaic karyotype who presented with atypical genitalia at birth. On examination, the external genitalia showed asymmetry of the labioscrotal folds, an empty right fold, a 2.5 cm phallic structure, and a perineal urethral meatus. Imaging studies revealed a uterus and a vaginal cavity, as well as an ovotestis on the left side and an ovarian remnant on the right side. An unexpected increase in testosterone level was observed. Cytogenetics analysis confirmed a mosaic karyotype with 54% of 46,XX and 46% 47,XXY cells. Molecular genetic analysis revealed no mutations in the genes involved in gonadal development. These findings are discussed and the clinical characteristics of the reported cases of 46,XX/47,XXY with OT-DSD are summarized. In conclusion, atypical genitalia leads to the early diagnosis of the rare 46,XX/47,XXY mosaicism with OT-DSD. Mosaicism should be considered in all cryptorchidism cases. Persistent Müllerian structures were common, and the nearly male phenotype of the external genitalia led parents to prefer the male sex of rearing.

Anti-N-methyl-D-aspartate Receptor Encephalitis in Turner Syndrome with 45,X/46,X,idic(X)(p11.4) Mosaics.

A 46-year-old woman with Turner syndrome (TS) (45,X/46,X,idic (X) (p11.4) mosaic) presented with a fever, unresponsiveness, hyperhidrosis, and rigidity approximately one month after episodes of confusion and suicide attempts, prompting a diagnosis of schizophrenia. Cerebrospinal fluid (CSF) showed mild hypercellularity with oligoclonal bands. Brain and abdominal magnetic resonance imaging showed no abnormalities. Bizarre upper-extremity movements and spasms followed the trial administration of acyclovir, and autoimmune encephalitis was suspected. Intensive immunotherapy was initiated, and the symptoms improved. Anti-N-methyl-D-aspartate receptor (anti-NMDAR) encephalitis was diagnosed based on the presence of anti-NMDAR antibodies in her spinal fluid. This case represents a rare presentation of anti-NMDAR encephalitis in TS, which is susceptible to autoimmune disease complications.

Mosaic SUFU mutation associated with a mild phenotype of multiple hereditary infundibulocystic basal cell carcinoma syndrome.

Multiple hereditary infundibulocystic basal cell carcinoma syndrome (MHIBCC), an autosomal dominant disorder caused by variants in SUFU, is characterized by numerous infundibulocystic basal cell carcinomas (IBCCs). In this report, we present a possible case of mosaic MHIBCC. A 57-year-old woman underwent the removal of four papules on her face, which were diagnosed as IBCCs. Exome sequencing revealed a SUFU c.1022+1G>A mutation within the skin tumor. The same mutation was detected in her blood but at a lower allele frequency. TA cloning revealed that the allele frequency of the mutation in the blood was 0.07. Additionally, tumor assessment revealed loss of heterozygosity (LOH) in chromosome 10, including the SUFU locus. These results indicate the patient had mosaicism for the SUFU mutation in normal tissues, aligning with the mosaic MHIBCC diagnosis. This, combined with LOH, likely contributed to IBCC development. Mosaic MHIBCC may present with milder symptoms. However, it may still increase the risk of developing brain tumors and more aggressive basal cell carcinoma. The possibility of mosaicism should be investigated in mild MHIBCC cases, where standard genetic tests fail to detect SUFU germline variants.

Mixed Gonadal Dysgenesis with 45,X/46,X,idic(Y)/46,XY Karyotype: A Case Report.

Background: The purpose of the current study was to report a case with 45,X/46,XY/46,X,idic(Yp) mosaicism showing the male phenotype with mixed gonadal dysgenesis. Case Presentation: A 27 year-old individual, phenotypically male, presented with azoospermia and a micropenis. Both testes were not visualized in the scrotal sac. Due to the presence of a small-sized uterus, the individual was referred to the KSHEMA Center for Genetic Services for chromosomal analysis. Karyotyping revealed a mosaic karyotype of 45,X[44]/46,XY[5]/46,X,idic(Yp)[1]. This finding was further confirmed through fluorescent in situ hybridization (FISH) analysis. The individual's mosaic karyotype consisted of three cell lines, with a higher proportion of the 45,X cell line and lower proportions of the idic(Yp) and 46,XY cell lines. It is worth noting that this mosaic condition in postnatal peripheral blood has not been reported in the literature thus far. Conclusion: The case report demonstrated the importance of performing karyotype and FISH analysis in understanding genetic defects including mosaicism and other chromosomal aberrations, which can influence not only growth and puberty but also sexual development and maturation. Hence, performing cytogenetic and molecular cytogenetic analysis will help clinicians to take a further step in understanding and managing the condition.

Detection of Germline Mosaicism for Robertsonian Translocation 14;14: A Case Report.

Background: Chromosomal structural rearrangements can lead to fertility problems and recurrent miscarriages. The intricate interplay of genetics during human development can lead to subtle anomalies that may affect reproduction. Case Presentation: A 33-year-old woman sought fertility treatment after experiencing six miscarriages. Products of conception from the final pregnancy loss had been karyotyped, revealing a Robertsonian translocation (RT), involving chromosome 14. Fertility investigations showed low anti-Mullerian hormone (AMH) levels but otherwise normal female characteristics with normal sperm parameters of her husband were observed and both partners having a normal karyotype. Two embryos were transferred in an IVF cycle but neither resulted in a successful pregnancy. Subsequently, preimplantation genetic testing for aneuploidy (PGT-A) was applied to trophectoderm biopsy specimens from 4 embryos, which revealed abnormalities involving chromosome 14. Sperm aneuploidy testing failed to detect any increase in the incidence of aneuploidy affecting chromosome 14. Further embryos genetic testing indicated that all identified chromosome 14 abnormalities in the embryos had a maternal (oocyte) origin. Conclusion: This case underscores challenges in diagnosing and managing germline mosaicism in fertility. A maternal 14;14 Robertsonian translocation, undetected in the patient's blood but impacting oocytes, likely explains recurrent miscarriage and observed embryo aneuploidies. Genetic mosaicism in reproductive medicine highlights the necessity for advanced testing and personalized treatments. Data integration from various genetic analyses could enhance managing treatment expectations and improving fertility experiences.

Double somatic mosaicism in Marfan syndrome.

Marfan syndrome (MFS) is a hereditary systemic connective tissue disorder with great clinical variability. It is caused by heterozygous pathogenic variants in the FBN1 gene. Cardinal manifestations involve the cardiovascular, ocular, and skeletal systems. Clinical diagnosis is based on the revised Ghent nosology. We present the case of a child with a Marfan systemic score of 9 whose genetic study revealed two pathogenic mosaic frameshift variants in the FBN1 gene. Mosaicism is very rare in patients diagnosed with MFS, and this is the first description of a patient with two pathogenic mosaic variants in the FBN1 gene. Both variants are present in cells derived from ectodermal (buccal swab) and mesodermal (leukocyte) tissues, suggesting a mutation prior to gastrulation. We propose a defective repair of the de novo variant in the complementary strand as the mechanism that led this individual to be a carrier of two different populations of mutant cells carrying adjacent variants.

Facial Segmental Infantile Haemangioma: A Cutaneous Mosaicism Quandary.

Mosaicism has long been considered the underlying mechanism of segmental infantile hemangiomas (SIH). This was a prospective pilot case-control study conducted with the objective to quantify the percentage overlap of silhouettes of facial SIH with those of Blaschko lines (the most well studied archetypical pattern of mosaicism on face) as compared to other mosaic disorders on face. Lesional silhouettes of 8 patients with SIH (Group A) and 6 patients with other facial dermatosis known to have blaschkoidal distribution (Group B), were overlapped on a standardized template with Blaschkoidal lines on the frontal view of face. The alignment was done via the auto align tool of Photoshop and the percentage of overlap was calculated with an online image comparison software (IMGonline.com.ua). There was a significant difference in mean overlap in Group A (72.92 ± 15.6 %) as compared to Group B (90.1 ± 4.3%; P=0.018). Hence, we concluded that facial SIH do not follow lines of Blaschko.

Confined placental mosaicism with trisomy 13 complicated by severe preeclampsia: A case report and literature review.

A 31-year-old primiparous woman underwent non-invasive prenatal testing. The result was trisomy 13 (T13) positive. The chromosome 13 t-statistics (Z-score) was significantly high. The result of amniocentesis was normal karyotype (46,XX). Detailed ultrasound showed no fetal structural abnormalities. We suspected T13 confined placental mosaicism (CPM) and observed the course naturally. From the late second trimester, severe fetal growth restriction manifested followed by proteinuria and hypertension, diagnosing her with preeclampsia (PE). At 35 + 5 weeks, emergent cesarean section was required, yielding a 1480 g female infant. We sampled five locations of chorionic villi in the placenta. T13 cells dominated cells with normal karyotypes in all parts and the rate of trisomic cells ranged from 57% to 96%, which were generally high rate. None developed PE in reported T13 CPM cases and this is the first case of PE. The dominancy of T13 cells can be associated with PE development.

Post-zygotic mosaicism of SMARCB1 variants in patients with rhabdoid tumors: a not so rare condition exposing to successive tumors.

BACKGROUND: Rhabdoid tumors (RT) are aggressive, rare tumors predominantly affecting young children, characterized by bi-allelic SMARCB1 gene inactivation. While most SMARCB1 alterations are acquired de novo, a third of cases exhibit germline alterations, defining Rhabdoid Tumors Predisposition Syndrome (RTPS1). With increased sensitivity of next-generation sequencing (NGS), mosaicisms in genes linked to genetic diseases are more detectable. This study focuses on exploring SMARCB1 germline alterations, notably mosaicism in blood samples of children with RT and in parents, using a custom NGS panel. METHODS: A cohort of 280 children and 140 parents with germline analysis was studied. Germline DNA from 111 children with RT and 32 parents were re-analyzed with a custom NGS panel with 1,500X average depth targeting the SMARCB1 gene to identify intragenic variants not detected with conventional low-sensitivity methods. Follow-up data was obtained for 77 patients. RESULTS: Nine previously undetected mosaicism cases were identified, totaling 17/280 patients with a mosaic variant (6.1%) in the cohort, with variant allele frequencies between 0.9% and 33%, thus highlighting the prior underestimation of its prevalence. Follow-up data showed that 4 out of 7 survivors with mosaic variants developed distinct novel tumors, two sharing SMARCB1 alterations with the initial tumor, emphasizing the potential clinical impact of SMARCB1 mosaicism. CONCLUSIONS: The hitherto underestimated rate of SMARCB1 mosaicism in RT underscores the need for optimized genetic counseling and oncological monitoring. The findings have significant medical implications, considering the dire prognosis of RT.

Detection of trisomy 9 mosaicism in the second trimester screening by abnormal level of biochemical markers.

Trisomy 9 is a rare chromosomal abnormality that occurs in both mosaic and non-mosaic states. The present study reports a case of mosaic trisomy 9 detected during pregnancy in a 41-year-old woman in the second trimester screening. Maternal serum screening results were used to diagnose a chromosomal abnormality in utero. The results were validated by karyotyping. High levels of alpha-fetoprotein and low levels of unconjugated estriol (uE3), human chorionic gonadotropin (hCG), and inhibin A indicate a high risk for chromosomal abnormalities, including trisomy 18. Amniotic fluid karyotyping revealed 47, XX, +9 (30)/46, XX (20) in the fetus. Because a high level (60%) of mosaicism for trisomy 9 in the fetus can affect many parts of the body, the pregnancy was terminated. It seems that a significant reduction in the levels of hCG and uE3 is an informative marker for the detection of chromosomal abnormalities such as trisomy 9.

BEAM: A combinatorial recombinase toolbox for binary gene expression and mosaic genetic analysis.

We describe a binary expression aleatory mosaic (BEAM) system, which relies on DNA delivery by transfection or viral transduction along with nested recombinase activity to generate two genetically distinct, non-overlapping populations of cells for comparative analysis. Control cells labeled with red fluorescent protein (RFP) can be directly compared with experimental cells manipulated by genetic gain or loss of function and labeled with GFP. Importantly, BEAM incorporates recombinase-dependent signal amplification and delayed reporter expression to enable sharper delineation of control and experimental cells and to improve reliability relative to existing methods. We applied BEAM to a variety of known phenotypes to illustrate its advantages for identifying temporally or spatially aberrant phenotypes, for revealing changes in cell proliferation or death, and for controlling for procedural variability. In addition, we used BEAM to test the cortical protomap hypothesis at the individual radial unit level, revealing that area identity is cell autonomously specified in adjacent radial units.

Complex genomic rearrangements of the Y chromosome in a premature infant.

BACKGROUND: Chromoanagenesis is an umbrella term used to describe catastrophic "all at once" cellular events leading to the chaotic reconstruction of chromosomes. It is characterized by numerous rearrangements involving a small number of chromosomes/loci, copy number gains in combination with deletions, reconstruction of chromosomal fragments with improper order/orientation, and preserved heterozygosity in copy number neutral regions. Chromoanagesis is frequently described in association with cancer; however, it has also been described in the germline. The clinical features associated with constitutional chromoanagenesis are typically due to copy number changes and/or disruption of genes or regulatory regions. CASE PRESENTATION: We present an 8-year-old male patient with complex rearrangements of the Y chromosome including a ring Y chromosome, a derivative Y;21 chromosome, and a complex rearranged Y chromosome. These chromosomes were characterized by G-banded chromosome analysis, SNP microarray, interphase FISH, and metaphase FISH. The mechanism(s) by which these rearrangements occurred is unclear; however, it is evocative of chromoanagenesis. CONCLUSION: This case is a novel example of suspected germline chromoanagenesis leading to large copy number changes that are well-tolerated, possibly because only the sex chromosomes are affected.

Experience of the first adult-focussed undiagnosed disease program in Australia (AHA-UDP): solving rare and puzzling genetic disorders is ageless.

BACKGROUND: Significant recent efforts have facilitated increased access to clinical genetics assessment and genomic sequencing for children with rare diseases in many centres, but there remains a service gap for adults. The Austin Health Adult Undiagnosed Disease Program (AHA-UDP) was designed to complement existing UDP programs that focus on paediatric rare diseases and address an area of unmet diagnostic need for adults with undiagnosed rare conditions in Victoria, Australia. It was conducted at a large Victorian hospital to demonstrate the benefits of bringing genomic techniques currently used predominantly in a research setting into hospital clinical practice, and identify the benefits of enrolling adults with undiagnosed rare diseases into a UDP program. The main objectives were to identify the causal mutation for a variety of diseases of individuals and families enrolled, and to discover novel disease genes. METHODS: Unsolved patients in whom standard genomic diagnostic techniques such as targeted gene panel, exome-wide next generation sequencing, and/or chromosomal microarray, had already been performed were recruited. Genome sequencing and enhanced genomic analysis from the research setting were applied to aid novel gene discovery. RESULTS: In total, 16/50 (32%) families/cases were solved. One or more candidate variants of uncertain significance were detected in 18/50 (36%) families. No candidate variants were identified in 16/50 (32%) families. Two novel disease genes (TOP3B, PRKACB) and two novel genotype-phenotype correlations (NARS, and KMT2C genes) were identified. Three out of eight patients with suspected mosaic tuberous sclerosis complex had their diagnosis confirmed which provided reproductive options for two patients. The utility of confirming diagnoses for patients with mosaic conditions (using high read depth sequencing and ddPCR) was not specifically envisaged at the onset of the project, but the flexibility to offer recruitment and analyses on an as-needed basis proved to be a strength of the AHA-UDP. CONCLUSION: AHA-UDP demonstrates the utility of a UDP approach applying genome sequencing approaches in diagnosing adults with rare diseases who have had uninformative conventional genetic analysis, informing clinical management, recurrence risk, and recommendations for relatives.

Fetus Conceived via In Vitro Fertilization With Mosaic Uniparental Isodisomy and Two Balanced Translocations.

We present a case of a fetus acquiring two different balanced translocations from each parent and subsequent uniparental isodisomy from postzygotic loss of a paternal chromosome. Balanced chromosomal translocations occur in 0.14% of the population and increase the risk of other genetic abnormalities, such as uniparental disomy (UPD) and mosaicism. Preimplantation genetic testing (PGT) can identify some genetic abnormalities. Translocations t(6;21) and t(5;15) have been reported individually but never together in a viable fetus. A non-consanguineous couple who were known carriers of two different balanced translocations conceived via classic in vitro fertilization (IVF). They had a normal PGT completed. Chorionic villus sampling (CVS) revealed that the fetus had received t(6;21) from the mother and t(5;15) from the father. The probability of the fetus acquiring both translocations was 2.8%. CVS also revealed UPD of chromosome 14. Amniocentesis was performed, which was consistent with the CVS in detecting the balanced translocations but provided more information about the UPD, determining that it was a mosaic maternal uniparental isodisomy of chromosome 14 (UPD(14)mat). The couple underwent genetic counseling to discuss the above findings and ultimately decided on dilation and evacuation at 17 weeks of gestation. The likelihood of conception of this fetus and survival past the first trimester is extremely rare. These specific chromosomal translocations and (UPD(14)mat) have never been reported before. This case emphasizes the concomitant nature of imprinted genes, resulting in multiple genetically unique alterations. This report also highlights the limitations of PGT, CVS, and amniocentesis in being reproducibly consistent, which is important to discuss prior to IVF conception.

Chromosomal instability in a patient with ring chromosome 14 syndrome: a case report.

BACKGROUND: Ring chromosome 14 syndrome is a rare disorder primarily marked by early-onset epilepsy, microcephaly, distinctive craniofacial features, hypotonia, intellectual disability, and delay in both development and language acquisition. CASE PRESENTATION: A 21-year-old woman with a history of epileptic seizures since the age of 1.5 years presented with distinctive craniofacial features, including a prominent and narrow forehead, sparse and short eyebrows, palpebral ptosis, horizontal palpebral fissures, a broad nasal bridge, a prominent nasal tip, a flat philtrum, hypertelorism, midfacial hypoplasia, horizontal labial fissures, a thin upper lip, crowded teeth, an ogival palate, retrognathia, and a wide neck. Additional physical abnormalities included kyphosis, lumbar scoliosis, pectus carinatum, cubitus valgus, thenar and hypothenar hypoplasia, bilateral hallux valgus, shortening of the Achilles tendon on the left foot, and hypoplasia of the labia minora. Chromosomal analysis identified a ring 14 chromosome with breakpoints in p11 and q32.33. An aCGH study revealed a ~ 1.7 Mb deletion on chromosome 14qter, encompassing 23 genes. Genomic instability was evidenced by the presence of micronuclei and aneuploidies involving the ring and other chromosomes. CONCLUSION: The clinical features of our patient closely resembled those observed in other individuals with ring chromosome 14 syndrome. The most important point was that we were able to verify an instability of the r(14) chromosome, mainly involving anaphasic lags and its exclusion from the nucleus in the form of a micronucleus.

Unusual sex chromosomal DSD in a domestic Shorthair cat with a 37,X/38,XY mosaic karyotype.

BACKGROUND: Sex chromosome abnormalities associated with disorders of sexual development (DSD) are rarely described in cats, mainly due to the lack of chromossome studies that precisely reveal the condition. Genetic approaches are therefore required in order to detect sex chromossomes abnormalities as variations in the number and structure of chromosomes, or the presence of a second cell line as mosaicim or chimerism. CASE PRESENTATION: A male Shorthair cryptorchid cat was presented with clinical signs of anorexia, tenesmus and hyperthermia. Ultrasonography revealed a fluid-filled structure, with approximately 1 cm in diameter, adjacent to the descending colon. Computed tomography evidenced a tubular structure, ventral to the descending colon and caudal to the bladder, which extended cranially, through two branches. Histopathological evaluation confirmed the presence of two atrophic uterine horns and one hypoplastic testicle with epididymis at the end of one of the uterine horns. The end of the other uterine horn was attached to a structure composed by a mass of adipocytes. Cytogenetic analysis revealed a mosaic 37,X/38,XY karyotype. The two cell lines were found in 15% and 85% of the lymphocytes, respectively. Genetic analysis confirmed the presence of SRY and ZFY genes in blood and hair bulbs, and revealed a marked reduction in SRY expression in the testicle. Additionally, this case presented exceptionally rare features, such as a Leydig' cell tumour and a chronic endometritis in both uterine horns. CONCLUSIONS: Complete imaging workup, cytogenetic analysis and SRY gene expression should be systematically realized, in order to properly classify disorders of sexual development (DSD) in cats.

Prevalence, diagnostic features, and medical outcomes of females with Turner syndrome with a trisomy X cell line (45,X/47,XXX): Results from the InsighTS Registry.

Turner syndrome (TS) is defined by partial or complete absence of a sex chromosome. Little is known about the phenotype of individuals with TS mosaic with trisomy X (45,X/47,XXX or 45,X/46,XX/47,XXX) (~3% of TS). We compared the diagnostic, perinatal, medical, and neurodevelopmental comorbidities of mosaic 45,X/47,XXX (n = 35, 9.4%) with nonmosaic 45,X (n = 142) and mosaic 45,X/46,XX (n = 66). Females with 45,X/47,XXX had fewer neonatal concerns and lower prevalence of several TS-related diagnoses compared with 45,X; however the prevalence of neurodevelopmental and psychiatric diagnoses were not different. Compared to females with 45,X/46,XX, the 45,X/47,XXX group was significantly more likely to have structural renal anomalies (18% vs. 3%; p = 0.03). They were twice as likely to have congenital heart disease (32% vs. 15%, p = 0.08) and less likely to experience spontaneous menarche (46% vs. 75% of those over age 10, p = 0.06), although not statistically significant. Congenital anomalies, hypertension, and hearing loss were primarily attributable to a higher proportion of 45,X cells, while preserved ovarian function was most associated with a higher proportion of 46,XX cells. In this large TS cohort, 45,X/47,XXX was more common than previously reported, individuals were phenotypically less affected than those with 45,X, but did have trends for several more TS-related diagnoses than individuals with 45,X/46,XX.

Factors Associated With Mosaicism in Human Embryos: A Retrospective Study.

Objective This study aims to identify factors associated with mosaicism in human embryos at Hung Vuong Hospital. Methods We performed a retrospective analysis of data from 2018 to 2022, approved by the Hung Vuong Hospital Ethics Committee (CS/HV/23/15). We analyzed variables such as demographic characteristics, clinical measurements, and in-vitro fertilization (IVF) cycle outcomes to investigate their relationship with embryo mosaicism. Results A total of 73 couples undergoing IVF with preimplantation genetic testing (PGT) were included in the analysis. Among 308 embryos, 98 (31.8%) were mosaic, 124 (40.3%) were euploid, and 86 (27.9%) were aneuploid. Univariable analysis revealed that female age was significantly associated with increased odds of mosaicism (odd ratio (OR) = 1.11, 95% confidence interval (CI): 1.04 - 1.19, p = 0.003). Male age demonstrated a marginal association with mosaicism (OR = 1.05, 95% CI: 1.00 - 1.11, p = 0.07). Other factors, including body mass index (BMI), anti-Mullerian hormone (AMH) levels, blood types, and sperm quality, were not significantly associated with mosaicism. In the multivariable analysis, controlling for both female and male age, female age showed a trend toward significance (OR = 1.12, 95% CI: 1.02 - 1.23, p = 0.02), while male age showed no significant effect (OR = 0.99, 95% CI: 0.92 - 1.06, p = 0.75). Conclusions The findings suggest that female age is a critical factor influencing the occurrence of mosaicism in embryos. Further research is needed to fully understand the mechanisms underlying mosaicism in human embryos.