Molecular cytogenetic characterization of a mosaic small supernumerary marker chromosome derived from chromosome Y in an azoospermic male: A case report

Prenatal detection of pure proximal 6q14.1 microduplication encompassing LCA5 gene: A variant of likely benign

Trisomy 6q is a recognizable syndrome which exhibits psychomotor/growth retardation, developmental/intellectual disabilities, feeding difficulties, facial dysmorphism, hearing loss, brain and heart malformations. The purpose of this study was to delineate the prenatal features of proximal 6q14.1 duplication in fetal period, which was rarely reported in clinic. Eight pregnant women who opted for amniocentesis due to the fetal ultrasound abnormalities, maternal serum screening or other indications for prenatal diagnosis between 2019 and 2020. Chromosomal microarray analysis and G-banding analysis were offered after informed consents were obtained. Cytogenetic prenatal investigation showed all fetuses presented normal karyotypes except case 4 exhibiting a balanced chromosomal translocation 46,XX,t (4;8)(p16;q24). The chromosomal microarray analysis detected 0.211-0.242 Mb duplications of 6q14.1 (chr6: 80109532-80351666, hg19) in all 8 cases, encompassing the morbid gene LCA5 in common. Seven pregnant women (P1-P7) continued their pregnancies and delivered healthy infants at term while the parents of case 8 opted for termination of pregnancy for severe abnormal ultrasound findings. Overall, all neonates were in a good healthy condition with no evident anomalies, ranging from 2 m to 16 m. It is proposed that 6q14.1 duplication involving LCA5 gene detected in our study might be variants of likely benign. However, further large-scale studies should be gathered to assess its pathogenicity. To our knowledge, our study is the first report focusing on prenatally detected proximal 6q14.1 duplication, accompanied by detailed clinic phenotypes. Diverse ultrasound findings were observed in these cases, ranging from normal to abnormal. More evidence should be gathered to interpret the prenatal genotype-phenotype correlation of 6q14.1 duplication. For these cases with 6q14.1 microduplication, long term follow up should be carried out in case abnormal clinical symptoms or developmental-behavioral disorders emerge.

Molecular cytogenetic characterization of 1q42.3q44 deletion and 8q24.3 duplication in a fetus with single umbilical artery and ventricular septal defects

OBJECTIVE

We present prenatal diagnosis and molecular cytogenetic characterization of a chromosome 1q42.3q44 deletion and 8q24.3 duplication in a fetus with single umbilical artery and ventricular septal defects, and we discuss the genotype-phenotype correlation.

CASE REPORT

Here, we describe a fetus with abnormal sonography findings showing a single umbilical artery and ventricular septal defects. Conventional karyotyping initially described the fetus as 46,XX,1q? and molecular cytogenetic analysis (CMA) revealed a 13-Mb deletion and 4.6-Mb duplication of regions 1q42.3q44 and 8q24.3, respectively. The father's karyotype was 46,XY. The mother's karyotype was 46,XX,t(1;8)(q42;q24). Therefore, the karyotype of the fetus was identified as 46,XX,der(1)t(1;8)(q42;q24) mat. After genetic counseling, the couple chose to terminate the pregnancy. We suggest that the ACTN2, RYR2 and PUF60 genes may be responsible for the ultrasound abnormalities observed in the fetus.

CONCLUSION

To the best of our knowledge, this is the first report of a 1q deletion and 8q duplication identified by prenatal detection. The application of karyotype analysis and CMA provides more accurate characterization for unidentified chromosomal anomalies, and benefits appropriate genetic counseling in the clinic.

Prenatal detection of terminal 9p24.3 microduplication encompassing DOCK8 gene: A variant of likely benign

Trisomy 9p is one of the most common chromosomal partial trisomies in newborns. However, reports on prenatal 9p microduplications are rare in the clinic. This study aimed to examine the genotype-phenotype correlation and assess the clinical significance of 9p24.3 microduplication encompassing the DOCK8 gene. Eight pregnant women underwent amniocentesis for cytogenetic and genetic testing for various indications for prenatal diagnosis from January 2019 to January 2020. Chromosomal karyotypic analysis was performed on G-band metaphases that were prepared from cultured amniotic fluid cells. Chromosomal microarray analysis was carried out to detect chromosomal copy number variations. We also performed a literature review on clinical data on similar 9p24.3 microduplications to determine the genotype-phenotype correlation. We detected 123-248-kb microduplications in the region of 9p24.3 (chr9: 208454-469022), involving part of or the entire DOCK8 gene. The indications for prenatal diagnosis mainly focused on the risk of maternal serum screening for trisomy 21/18, advanced maternal age, and increased nuchal translucency. No evident structural abnormalities were observed for all fetuses, except for case 5 who presented with increased nuchal translucency in prenatal ultrasound findings. Follow-up of postnatal health was performed and showed no apparent abnormalities for cases 1 to 6 after birth. The parents of case 7 chose to terminate the pregnancy while the parents of case 8 chose to continue the pregnancy. We propose that 9p24.3 microduplications that encompass part of or the entire DOCK8 gene are variants that might be benign. However, further large-scale studies are necessary to evaluate the clinical pathogenicity. For prenatal cases with 9p24.3 microduplication, postnatal health and growth should be followed up and assessed regularly from childhood to adulthood.

Prenatal detection and molecular cytogenetic characterization of 19q13.42 microduplication: three reported cases and literature review

Background

Trisomy 19q is a recognizable syndrome and associated with a wide spectrum of clinical phenotypes in clinic. The purpose of this study was to explore the prenatal phenotypes of 19q13.42 duplication, which was rarely reported in clinic.

Case presentation

Three pregnant women presenting diverse indications for prenatal diagnosis accepted amniocentesis: increased nuchal translucency and fetal pyelic separation (case 2) and high risk of maternal serum screening for Down syndrome (case 1 and case 3). Case 1 and case 2 shared similar duplicated locus in the region of 19q13.42, encompassing part NLRP12 gene. The latter inherited the chromosomal duplication from the mother with normal phenotypes. Case 3 carried a 1.445 Mb duplication in the 19q13.42q13.43 region. It was proposed that evolutionary duplication of NLRP12 gene could have a causative role in autoinflammatory diseases development. The genotype–phenotype correlation depends mainly on the duplicated size and functional genes involved, which is still yet to be determined. All pregnant women chose to continue the pregnancy and delivered healthy children with no apparent abnormalities.

Conclusions

The 19q13.42 microduplications in our study were the smallest fragments compared to previous literature. Our findings enriched the prenatal phenotypes for this chromosomal microscopic imbalance. It was proposed that long term follow up analysis should be guaranteed till adulthood to determine whether there will be other emerging clinical symptoms and developmental-behavioral disorders for such carriers.

Molecular cytogenetic studies of a male carrier with a unique (Y;14) translocation: Case report

BACKGROUND

Chromosome translocation is a genetic factor associated with male infertility. However, cases of Y chromosome/autosome translocation are rare. Individuals with translocation between the Y chromosome and an autosome have a variety of different clinical phenotypes. There is a need for further study of molecular cytogenetic feature of those with Y chromosome translocation.

METHODS

We reported that an apparently healthy 31-year-old man, 168 cm tall and weighing 65 kg, had a 2-year history of primary infertility after marriage. Clinical diagnostic techniques included semen analysis, hormone measurements, cytogenetic analysis, fluorescence in situ hybridization (FISH), and high-throughput multiplex ligation-dependent probe amplification semiconductor sequencing. Detailed genetic counseling was provided to the patient. Intracytoplasmic sperm injection treatment combined with preimplantation genetic diagnosis was chosen with the aim of achieving a successful pregnancy.

RESULTS

Semen analysis revealed cryptozoospermia. Hormone levels were within the normal limits. Sequencing results indicated the presence of the sex-determining region on Yp, and AZFa, AZFb, and AZFc regions on Yq. The patient's karyotype was 45,X,psu,dic(Y;14)(p11.3;q11.2), which was confirmed by cytogenetic analysis and FISH.

CONCLUSION

This study reports a case of cryptozoospermia in a male patient with a Y;14 chromosomal translocation. When clinical karyotyping has revealed potential Y chromosome abnormality, FISH or molecular detection should be further performed to facilitate identification of the chromosomal breakpoint.

Prenatal diagnosis of a de novo 15q11.2 microdeletion in a maternal inv(4)(p15q31) fetus with increased nuchal translucency: A case report and literature review

RATIONALE

15q11.2 microdeletion syndrome is a relatively rare chromosomal abnormality with incomplete penetrance and phenotypic variability. The reports on prenatal ultrasound abnormalities of fetus with 15q11.2 microdeletion are rare.

PATIENT CONCERNS

A 30-year-old woman was referred for genetic counseling and prenatal diagnosis at 19 weeks of gestation because of increased nuchal translucency in prenatal ultrasound findings and a history of spontaneous abortion.

DIAGNOSES

The cytogenetic analysis showed the karyotype of the fetus was 46,XY, inv(4)(p15q31) and chromosomal microarray analysis detected a 0.512 Mb deletion in 15q11.2 region. We recalled the parents to determine the origination of these chromosomal abnormalities.

INTERVENTIONS

The pregnant woman chose to continue the pregnancies and finally delivered a healthy male infant at 39 weeks.

OUTCOMES

The fetus inherited the inv(4)(p15q31) from his mother while the deletion in 15q11.2 was identified as de novo. Given the normal phenotype of the mother, it was reasonable to assume that the maternal inherited inv(4) in the fetus would not increase the risk of his abnormal phenotype. However, the pathogenicity of the microdeletion in 15q11.2 for the infant is unknown and long-term follow-up of progeny should be paid more attention.

LESSONS

The combined application of traditional banding technique and molecular cytogenetic techniques can not only detect chromosomal structural abnormalities, but also identify the subchromosomal imbalances, which is beneficial to genetic counselling and would offer more guidance to prenatal diagnosis.

Molecular characterization of small supernumerary marker chromosomes derived from chromosome 14/22 detected in adult women with fertility problems: Three case reports and literature review

RATIONALE

Small supernumerary marker chromosomes (sSMC) are structurally abnormal chromosomes, which can be detected in patients with developmental retardation, infertile problems, and prenatal fetus. We report 3 adult female with fertility problems carrying sSMC(14/22) and aim to explore the correlation between sSMC(14/22) and fertility problems in women.

PATIENT CONCERNS

Three Chinese female patients were referred for infertility consultation in our hospital.

DIAGNOSES

The karyotype of these 3 patients were 47, XX, +mar. The chromosome microarray analysis (CMA) detected various chromosomal duplications and deletions in the 3 cases: a 0.49Mb gain of 5q32 for case 1; a 0.54Mb gain of 14q32.33 and a 1.83Mb gain of 16p11.2 for case 2; a 0.37Mb loss of 13q21.2q21.31 and a 0.12Mb gain of Xp11.2 for case 3. Fluorescence in situ hybridization (FISH) using the specific probes for chromosomes 13/21, 14/22, and 15 was applied to identify the origination of these sSMC, which were all finally identified as sSMC(14/22).

INTERVENTIONS

Case 1 underwent the artificial reproductive technology to get her offspring and finally delivered a healthy male infant at 39 weeks. Case 2 did not plan to choose in vitro fertilization (IVF) to get offspring. Case 3 refused to do assisted reproductive technology.

OUTCOMES

The genotype-phenotype correlation of sSMC(14/22) remain unclear. However, the existence of sSMC(14/22) might negatively affect the fertility ability in sSMC female carriers.

LESSONS

The combined application of traditional banding technique and molecular cytogenetic techniques can better identify more details of sSMC. For sSMC carriers with fertility problems, they could get their offsprings through assisted reproductive technologies after comprehensive fertility assessment.

Prenatal Diagnosis and Molecular Cytogenetic Characterization of Copy Number Variations on 4p15.2p16.3, Xp22.31, and 12p11.1q11 in a Fetus with Ultrasound Anomalies: A Case Report and Literature Review

Chromosomal rearrangements, such as duplications/deletions, can lead to a variety of genetic disorders. Herein, we reported a prenatal case with right aortic arch and aberrant left subclavian artery, consisting of a complex chromosomal copy number variations. Routine cytogenetic analysis described the chromosomal karyotype as 46,XY, add (2)(q37) for the fetus. However, the chromosomal microarray analysis (CMA) identified a 22.4 Mb duplication in chromosome 4p16.3p15.2, a 3.96 Mb microduplication in 12p11.1q11, and a 1.68 Mb microdeletion in Xp22.31. Fluorescence in situ hybridization (FISH) using a chromosome 4 painting probe was found to hybridize to the terminal of chromosome 2q on the fetus, thus confirming that the extra genetic materials of chromosome 2 was actually trisomy 4p detected through CMA. Meanwhile, the parental karyotypes were normal, which proved that the add (2) was de novo for fetus. The duplication of Wolf-Hirschhorn syndrome critical region (WHSCR) and X-linked recessive ichthyosis associated with Xp22.31 deletion separately were considered potentially pathogenic causes although other abnormalities involving these syndromes were not observed. For prenatal cases, the combined utilization of ultrasonography, traditional cytogenetic, and molecular diagnosis technology will enhance better diagnostic benefits, offer more detailed genetic counselling, and assess the prognosis of the fetuses.