Stepwise molecular-genetic examination in aborted fetuses.

OBJECTIVE: The evaluation of quantitative fluorescence PCR (QF-PCR) and single nucleotide polymorphism array (SNP array) analysis for the identification of chromosomal abnormalities in products of conception (POC). MATERIALS AND METHODS: A total of 1,094 POC samples were processed at Gennet in the years 2018-2020. Chromosomal aneuploidies were tested by QF-PCR using a Omnibor set (STR markers 13, 18, 21, X a Y), SAB-I set (STR markers 2, 7, 15, 16, 22), SAB-II set (from November 2019, STR markers 4, 6, 14) followed by SNP array analysis (Illumina) on samples with a negative QF-PCR result. All POC samples were tested for maternal contamination. RESULTS: After exclusion of maternal contamination (32% samples) the total number of 742 POC samples were tested by QF-PCR. Chromosomal aneuploidies were found in 273 POC samples (36.8%). Then, 469 QF-PCR negative POC samples were tested by SNP array analysis. Normal female/male profile was confirmed in 402 samples (85.7%) and chromosomal aneuploidies and chromosomal aberrations (deletion/duplication > 10 Mb) in 51 samples (10.9%). Microdeletion/microduplication was found in 16 POC samples (3.4%), two were classified as pathogenic variants and 14 as variants of unknown significance. In a group of women > 35 years of age, statistically significant increase of the chromosomal abnormalities was confirmed. No statistically significant difference between the in vitro fertilization group and the group of spontaneous conception was found. CONCLUSION: The application of the molecular work-up based on the stepwise use of QF-PCR and SNP array clarifies the cause of the abortion in 43% POC samples. The overall detection rate in the I. trimester was 50.4%.

Genome-wide uniparental diploidy of all paternal chromosomes in an 11-year-old girl with deafness and without malignancy.

Approximately 20 cases of genome-wide uniparental disomy or diploidy (GWUPD) as mosaicism have previously been reported. We present the case of an 11-year-old deaf girl with a paternal uniparental diploidy or isodisomy with a genome-wide loss of heterozygosity (LOH). The patient was originally tested for non-syndromic deafness, and the novel variant p.V234I in the ESRRB gene was found in a homozygous state. Our female proband is the seventh patient diagnosed with GWUPD at a later age and is probably the least affected of the seven, as she has not yet presented any malignancy. Most, if not all, reported patients with GWUPD whose clinical details have been published have developed malignancy, and some of those patient developed malignancy several times. Therefore, our patient has a high risk of malignancy and is carefully monitored by a specific outpatient pediatric oncology program. This observation seems to be novel and unique in a GWUPD patient. Our study is also unique as it not only provides very detailed documentation of the genomic situations of various tissues but also reports differences in the mosaic ratios between the blood and saliva, as well as a normal biparental allelic situation in the skin and biliary duct. Additionally, we were able to demonstrate that the mosaic ratio in the blood remained stable even after 3 years and has not changed over a longer period.

Diagnóstico genético preimplantacional de la enfermedad de Charcot-Marie-Tooth ligada al cromosoma X mediante análisis de ligamiento indirect / Preimplantation genetic diagnosis of X-linked Charcot-Marie-Tooth disease by indirect linkage analysis

Objetivo: Presentar un enfoque metodológico del diagnóstico genético preimplantacional (DGP) como opción para embarazos no afectados en parejas en edad reproductiva con riesgo genético de neuropatía periférica dominante por enfermedad de Charcot-Marie-Tooth tipo 1 ligada al cromosoma X. Pacientes y métodos: Llevamos a cabo el DGP de enfermedad de Charcot-Marie-Tooth tipo 1 ligada al cromosoma X utilizando un análisis de ligamiento indirecto/haplotificación, durante el cual logramos excluir los embriones portadores de un haplotipo de alto riesgo ligado a la mutación causal p.Leu9Phe en el gen GJB1. Resultados: Dentro del ciclo de DGP, examinamos 4 blastómeros biopsiados de los embriones en fase de división, y recomendamos la transferencia de 3 embriones. Dos embriones fueron implantados en el útero; sin embargo, el resultado fue un embarazo único con un descendiente varón. Transcurridos 3 años, la pareja regresó con un embarazo espontáneo. La biopsia coriónica de este embarazo reveló el sexo femenino y una inversión pericéntrica del cromosoma 5 en el 70% de las células fetales cultivadas. Conclusión: Utilizando el análisis de ligamiento indirecto, el DGP puede ayudar a identificar durante el cribado los defectos genéticos ligados al cromosoma X, eludiendo por tanto los problemas potenciales con el aborto (AU)

Objective: To present methodical approach of preimplantation genetic diagnosis (PGD) as an option for an unaffected pregnancy in reproductive-age couples who have a genetic risk of the X-linked dominant peripheral neuropathy Charcot-Marie-Tooth type 1 disease. Patients and methods: We performed PGD of X-linked Charcot-Marie-Tooth type 1 disease using haplotyping/indirect linkage analysis, when during analysis we reach to exclude embryos that carry a high-risk haplotype linked to the causal mutation p.Leu9Phe in the GJB1 gene. Results: Within the PGD cycle, we examined 4 blastomeres biopsied from cleavage-stage embryos and recommended 3 embryos for transfer. Two embryos were implanted into the uterus; however, it resulted in a singleton pregnancy with a male descendant. Three years later, the couple returned again with spontaneous gravidity. A chorionic biopsy examination of this gravidity ascertained the female sex and a pericentric inversion of chromosome 5 in 70% of the cultivated foetal cells. Conclusion: Using indirect linkage analysis, PGD may help to identify genetic X-linked defects within embryos during screening, thereby circumventing the potential problems with abortion (AU)

Preimplantation genetic diagnosis of X-linked Charcot-Marie-Tooth disease by indirect linkage analysis. / Diagnóstico genético preimplantacional de la enfermedad de Charcot-Marie-Tooth ligada al cromosoma X mediante análisis de ligamiento indirecto.

OBJECTIVE: To present methodical approach of preimplantation genetic diagnosis (PGD) as an option for an unaffected pregnancy in reproductive-age couples who have a genetic risk of the X-linked dominant peripheral neuropathy Charcot-Marie-Tooth type 1 disease. PATIENTS AND METHODS: We performed PGD of X-linked Charcot-Marie-Tooth type 1 disease using haplotyping/indirect linkage analysis, when during analysis we reach to exclude embryos that carry a high-risk haplotype linked to the causal mutation p.Leu9Phe in the GJB1 gene. RESULTS: Within the PGD cycle, we examined 4 blastomeres biopsied from cleavage-stage embryos and recommended 3 embryos for transfer. Two embryos were implanted into the uterus; however, it resulted in a singleton pregnancy with a male descendant. Three years later, the couple returned again with spontaneous gravidity. A chorionic biopsy examination of this gravidity ascertained the female sex and a pericentric inversion of chromosome 5 in 70% of the cultivated foetal cells. CONCLUSION: Using indirect linkage analysis, PGD may help to identify genetic X-linked defects within embryos during screening, thereby circumventing the potential problems with abortion.