The decision on the embryo to transfer after Preimplantation Genetic Diagnosis for X-autosome reciprocal translocation in male carrier

Characteristics and clinical evaluation of X chromosome translocations

BACKGROUND

Individuals with X chromosomal translocations, variable phenotypes, and a high risk of live birth defects are of interest for scientific study. These characteristics are related to differential breakpoints and various types of chromosomal abnormalities. To investigate the effects of X chromosome translocation on clinical phenotype, a retrospective analysis of clinical data for patients with X chromosome translocation was conducted. Karyotype analysis plus endocrine evaluation was utilized for all the patients. Additional semen analysis and Y chromosome microdeletions were assessed in male patients.

RESULTS

X chromosome translocations were detected in ten cases, including seven females and three males. Infantile uterus and no ovaries were detected in case 1 (FSH: 114 IU/L, LH: 30.90 mIU/mL, E2: < 5.00 pg/ml), and the karyotype was confirmed as 46,X,t(X;22)(q25;q11.2) in case 1. Infantile uterus and small ovaries were both visible in two cases (FSH: 34.80 IU/L, LH: 17.06 mIU/mL, E2: 15.37 pg/ml in case 2; FISH: 6.60 IU/L, LH: 1.69 mIU/mL, E2: 23.70 pg/ml in case 3). The karyotype was detected as 46,X,t(X;8)(q13;q11.2) in case 2 and 46,X,der(X)t(X;5)(q21;q31) in case 3. Normal reproductive hormone levels and fertility abilities were found for cases 4, 6 and 7. The karyotype were detected as 46,X,t(X;5)(p22.3;q22) in case 4 and 46,X,der(X)t(X;Y)(p22.3;q11.2) in cases 6 and 7. These patients exhibited unremarkable clinical manifestations but experienced a history of abnormal chromosomal pregnancy. Normal phenotype and a complex reciprocal translocation as 46,X,t(X;14;4)(q24;q22;q33) were observed in case 5 with a history of spontaneous abortions. In the three male patients, multiple semen analyses confirmed the absence of sperm. Y chromosome microdeletion and hormonal analyses were normal. The karyotypes were detected as 46,Y,t(X;8)(q26;q22), 46,Y,t(X;1)(q26;q23), 46,Y,t(X;3)(q26;p24), respectively.

CONCLUSIONS

Our study provides insights into individuals with X chromosome translocations. The clinical phenotypes are variable and unpredictable due to differences in breakpoints and X chromosome inactivation (XCI) patterns. Our results suggest that physicians should focus on the characteristics of the X chromosome translocations and provide personalized clinical evaluations in genetic counselling.

Azoospermia Secondary to a Novel X-Autosomal Reciprocal Translocation: 46,Y, t(X:16)(p22.1:p11.2)

Chromosomal translocations occur in 10 to 15% of men with azoospermia. Thirty distinct X-autosomal balanced reciprocal translocations have been reported in the literature thus far. We present a novel case of azoospermia with a karyotype of 46,Y,t(X:16)(p22.1:p11.2). A 26-year-old, healthy, active duty male Solider presented with his dependent female partner for primary infertility. Female anatomical and endocrine evaluations were normal. Initial male evaluation revealed azoospermia on multiple semen analyses. Further evaluation with a detailed physical exam and laboratory tests were normal except for an abnormal karyotype with a reciprocal translocation at chromosomes X and 16. An open testicular biopsy demonstrated 75% late spermatid maturation arrest confirming reproductive potential although significantly reduced. Men who present with azoospermia should undergo a full endocrine and genetic evaluation with a thorough physical evaluation by an urologist. They can have limited but successful reproductive outcomes if spermatozoa can be isolated during testicular biopsy. Given the high risk of producing genetically unbalanced embryos, genetic counseling and preimplantation genetic testing is essential before pursuing assisted reproductive technology. This case is the first X-autosomal balanced reciprocal translocations involving chromosome 16 and highlights the importance of the X chromosome during spermatogenesis.

Universal strategy for preimplantation genetic testing for cystic fibrosis based on next-generation sequencing

PURPOSE

We developed and applied a universal strategy for preimplantation genetic testing for all cystic fibrosis gene mutations (PGT-CF) based on next-generation sequencing (NGS).

METHODS

A molecular protocol was designed to diagnose all CF mutations at preimplantation stage. The detection of CF mutations was performed by direct gene sequencing and linkage strategy testing 38 specific SNPs located upstream and inside the gene for PGT-CF. Seventeen couples at risk of CF transmission decided to undergo PGT-CF. Trophectoderm cell biopsies were performed on days 5-6 blastocysts. PGT for aneuploidy (PGT-A) was performed from the same samples. Tested embryos were transferred on further natural cycles.

RESULTS

PGT was performed on 109 embryos. Fifteen CF mutations were tested. PGT-CF and PGT-A were conclusive for, respectively, 92.7% and 95.3% of the samples. A mean of 24.1 SNPs was informative per couple. After single embryo transfer on natural cycle, 81.3% of the transferred tested embryos implanted.

CONCLUSIONS

The present protocol based on the entire CFTR gene sequencing together with informative SNPs outside and inside the gene can be applied to diagnose all CF mutations at preimplantation stage.

Universal strategy for preimplantation genetic testing for cystic fibrosis based on next generation sequencing

Purpose

We developed and applied a universal strategy for preimplantation genetic testing for all cystic fibrosis gene mutations (PGT-CF) based on next-generation sequencing (NGS).

Methods

A molecular protocol was designed to diagnose all CF mutations at preimplantation stage. The detection of CF mutations was performed by direct gene sequencing and linkage strategy testing 38 specific SNPs located upstream and inside the gene for PGT-CF. Seventeen couples at risk of CF transmission decided to undergo PGT-CF. Trophectoderm cell biopsies were performed on day 5–6 blastocysts. PGT for aneuploidy (PGT-A) was performed from the same samples. Tested embryos were transferred on further natural cycles.

Results

PGT was performed on 109 embryos. Fifteen CF mutations were tested. PGT-CF and PGT-A were conclusive for respectively 92.7% and 95.3% of the samples. A mean of 24.1 SNPs was informative per couple. After a single embryo transfer on natural cycle, 81.3% of the transferred tested embryos were implanted.

Conclusions

The present protocol based on the entire CFTR gene together with informative SNPs outside and inside the gene can be applied to diagnose all CF mutations at preimplantation stage.

Electronic supplementary material

The online version of this article (10.1007/s10815-019-01635-2) contains supplementary material, which is available to authorized users.