A Rare Variant of Turner Syndrome (the X Isochromosome-X Syndrome): A Case Report

Background: Turner syndrome occurs in nearly one in every 2000-5000 female births. This syndrome is a genetic problem in the female phenotype and the most common sex chromosome anomaly. It is diagnosed based on clinical manifestations and cytogenetic examinations. The classic syndrome (i.e., monosomy X) makes up 50% of the cases while other forms contain X chromosome variants, which do not typically manifest as the classic X phenotype. Case Presentation: This study, presents a rare variant of Turner syndrome reported in a 20-year-old woman presenting with primary amenorrhea, hypothyroidism, and short stature who had hypergonadotropic hypogonadism with hypoplastic ovaries while without the clinical manifestations of the classic Turner syndrome. The karyotype was determined as X isochromosome-X syndrome [46 XXi (Xq)]. Conclusion: This rare syndrome occurs in approximately 7% of the cases of Turner syndrome. Rare variants of the syndrome should also be considered in female patients without the classic manifestations of Turner syndrome.

A rare familial rearrangement of chromosomes 9 and 15 associated with intellectual disability: a clinical and molecular study

Background There are many reports on rearrangements occurring separately in the regions of chromosomes 9p and 15q affected in the case under study. 15q duplication syndrome is caused by the presence of at least one extra maternally derived copy of the Prader–Willi/Angelman critical region. Trisomy 9p is the fourth most frequent chromosome anomaly with a clinically recognizable syndrome often accompanied by intellectual disability. Here we report a new case of a patient with maternally derived unique complex sSMC resulting in partial trisomy of both chromosomes 9 and 15 associated with intellectual disability. Case presentation We characterise a supernumerary derivative chromosome 15: 47,XY,+der(15)t(9;15)(p21.2;q13.2), likely resulting from 3:1 malsegregation during maternal gametogenesis. Chromosomal analysis showed that a phenotypically normal mother is a carrier of balanced translocation t(9;15)(p21.1;q13.2). Her 7-year-old son showed signs of intellectual disability and a number of physical abnormalities including bilateral cryptorchidism and congenital megaureter. The child’s magnetic resonance imaging showed changes in brain volume and in structural and functional connectivity revealing phenotypic changes caused by the presence of the extra chromosome material, whereas the mother’s brain MRI was normal. Sequence analyses of the microdissected der(15) chromosome detected two breakpoint regions: HSA9:25,928,021-26,157,441 (9p21.2 band) and HSA15:30,552,104-30,765,905 (15q13.2 band). The breakpoint region on chromosome HSA9 is poor in genetic features with several areas of high homology with the breakpoint region on chromosome 15. The breakpoint region on HSA15 is located in the area of a large segmental duplication. Conclusions We discuss the case of these phenotypic and brain MRI features in light of reported signatures for 9p partial trisomy and 15 duplication syndromes and analyze how the genomic characteristics of the found breakpoint regions have contributed to the origin of the derivative chromosome. We recommend MRI for all patients with a developmental delay, especially in cases with identified rearrangements, to accumulate more information on brain phenotypes related to chromosomal syndromes.

Intrinsic and extrinsic regulation of human fetal bone marrow haematopoiesis and perturbations in Down syndrome

Throughout postnatal life, haematopoiesis in the bone marrow (BM) maintains blood and immune cell production. Haematopoiesis first emerges in human BM at 12 post conception weeks while fetal liver (FL) haematopoiesis is still expanding. Yet, almost nothing is known about how fetal BM evolves to meet the highly specialised needs of the fetus and newborn infant. Here, we detail the development of fetal BM including stroma using single cell RNA-sequencing. We find that the full blood and immune cell repertoire is established in fetal BM in a short time window of 6-7 weeks early in the second trimester. Fetal BM promotes rapid and extensive diversification of myeloid cells, with granulocytes, eosinophils and dendritic cell (DC) subsets emerging for the first time. B-lymphocyte expansion occurs, in contrast with erythroid predominance in FL at the same gestational age. We identify transcriptional and functional differences that underlie tissue-specific identity and cellular diversification in fetal BM and FL. Finally, we reveal selective disruption of B-lymphocyte, erythroid and myeloid development due to cell intrinsic differentiation bias as well as extrinsic regulation through an altered microenvironment in the fetal BM from constitutional chromosome anomaly Down syndrome during this crucial developmental time window.

Quantitative Fluorescent Polymerase Chain Reaction for Prenatal Diagnosis and Its Application in Vietnam: A Literature Review

Early identification of fetal abnormalities is a huge challenge for modern obstetrics. Quantitative fluorescent polymerase chain reaction (QF-PCR) has quickly become an effective means of chromosome anomaly detection due to its advantages in terms of timing, manpower and accuracy. The QF-PCR results also make a significant change in clinicians’ attitude to some extent, assisting them providing parents with professional and valuable advice on pregnancy management. In this review, the advantages and drawbacks of QF-PCR will be explored. By reviewing studies published in Vietnamese Medical Journals, we conclude QF-PCR can become a potential screening test in the field of prenatal diagnosis.

PREVALENCE OF PERIODONTAL DISEASES IN CHILDREN WITH DOWN SYNDROME

Down syndrome – trisomy of 21 chromosome is the most common chromosome anomaly, which affects children worldwide. The aim of this study is to compare the distribution of periodontal disease among Down syndrome children and healthy children. 60 children and adolescents with Down syndrome and 60 healthy children were examined in the same age group. Plaque index (PI) (Silness&Loe), probing depth (PD) were registered. The plaque index of children with Down syndrome under 6 years is 0.81. For the children between 6-11 years, this index is 1.4 and for the third group it is 1,8. For the healthy children the values of the PI are: under 6 years – 0.9; between 6-11 – 1.2; between 11-15 – 2.2. The measured pocket depths of the children with DS for the three examined are as follows: under 6 years – 3.5; between 6-11 – 4.1; between 11-15 – 4.7. For the healthy children the values of the PPD are: under 6 years – 2.6; between 6-11 – 3.3; between 11-15 – 3.0. Conclusion: There are more frequent periodontal problems for Down syndrome children, which does not correspond with the level of their oral hygiene.

STRUCTURAL VARIATIONS OF CHROMOSOME 9

Partial trisomy of chromosome 9 has relatively frequently been observed in liveborn subjects. In the majority of the reported cases breaks occur in the centric segment of the long arm (q11-q13). Two characteristics of this chromosome part, i.e. 9qh+ and inv(9), have been studied. The results of a study of selected samples do not support an association between 9qh+ chromosome anomaly and reproductive failure. The frequency of inv(9) in different samples agrees with those reported by other investigators (1.11—2.32%). An excess of male carriers was found. Aneusomy of recombination has been observed in one case. Partial trisomy of chromosome seems to be the most frequently observed type of unbalanced structural aberration of autosomes in liveborn subjects. Up to now 50 cases have been reported. Three of these have been described as 9q trisomy, the others were 9p trisomies

C-banding and AgNOR-staining were still effective complementary methods to indentify chromosomal heteromorphisms and some structural abnormalities in prenatal diagnosis

Background In prenatal diagnosis, CMA has begun to emerge as a favorable alternative to karyotype analysis, but it could not identify balanced translocations, triploidies, inversion and heteromorphisms. Therefore, conventional cytogenetic and specific staining methods still play an important role in the work-up of chromosome anomaly. This study investigated the application of C-banding and AgNOR-staining techniques in prenatal diagnosis of chromosomal heteromorphisms and some structure abnormalities. Results Among the 2970 samples, the incidence of chromosomal heteromorphisms was 8.79% (261/2970). The most frequent was found to be chromosome Y (2.93%, 87/2970), followed by chromosome 1 (1.65 %, 49/2970), 9 (1.52 %, 45/2970), 22 (0.77 %, 23/2970) and 15 (0.64 %, 19/2970). We compared the incidence of chromosomal heteromorphisms between recurrent spontaneous abortion (RSA) group and control group. The frequency of autosomal hetermorphisms in RSA group was 7.63% higher than that in control group (5.78%), while the frequency of Y chromosomal heteromorphisms was 4.76% lower than that in control group (5.71%). Here we summarized 4 representative cases, inv (1) (p12q24), psu dic (4;17) (p16.3;p13.3), r(X)(p11; q21) and an isodicentric bisatellited chromosome to illustrate the application of C-banding or AgNOR-staining, CMA or NGS was performed to detect CNVs if necessary. Conclusions This study indicated that C-banding and AgNOR-staining were still effective complementary methods to identify chromosomal heteromorphisms and marker chromosomes or some structural rearrangements involving the centromere or acrocentric chromosomes. Our results suggested that there was no evidence for an association between chromosomal heteromorphisms and infertility or recurrent spontaneous abortions. Undoubtedly, sometimes we needed to combine the results of CMA or CNV-seq to comprehensively reflect the structure and aberration of chromosome segments. Thus, accurate karyotype reports and genetic counseling could be provided.

False Low-Risk Single Nucleotide Polymorphism–Based Noninvasive Prenatal Screening in Pentasomy 49,XXXXY

Introduction Pentasomy 49,XXXXY is a sex chromosome anomaly difficult to be diagnosed prenatally. We describe a patient of pentasomy 49,XXXXY with false low-risk results using a noninvasive prenatal screening (NIPS). A 30-year-old G1P0 woman presented at 336/7 weeks, secondary to sonographic fetal anomalies. She had low-risk NIPS at 136/7 weeks. Anatomy survey showed bilateral clubfeet, clinodactyly of the left fifth digit, micropenis, and echogenic bowel. Cytogenetics analysis revealed pentasomy 49,XXXXY syndrome. We report third-trimester sonographic features of a fetus with pentasomy 49,XXXXY and the importance of thorough pre- and posttest counseling for NIPS.

Characterization of a Complex Chromosomal Rearrangement Involving a de novo Duplication of 9p and 9q and a Deletion of 9q

Rearrangements of the distal region of 9p are important chromosome imbalances in human beings. Trisomy 9p is the fourth most frequent chromosome anomaly and is a clinically recognizable syndrome. Kleefstra syndrome, previously named 9q subtelomeric deletion syndrome, is either caused by a submicroscopic deletion in 9q34.3 or an intragenic mutation of EHMT1. We report a Mexican male patient with abnormal development, dysmorphism, systemic anomalies and a complex chromosomal rearrangement (CCR). GTG-banding revealed a 46,XY,add(9)(q34.3) karyotype, whereas array analysis resulted in arr[hg19] 9p24.3p23(203,861-11,842,172)×3, 9q34.3(138,959,881-139,753,294)×3, 9q34.3(139,784,913-141,020,389)×1. Array and karyotype analyses were normal in both parents. Partial duplication of 9p is one of the most commonly detected autosomal structural abnormalities in liveborn infants. A microdeletion in 9q34.3 corresponds to Kleefstra syndrome, whereas a microduplication in 9q34.3 shows a great clinical variability. Here, we present a CCR in a patient with multiple congenital anomalies who represents the first case with partial 9p trisomy, partial 9q trisomy and partial 9q monosomy.