Implementation and experience of an alternative QF-PCR and MLPA diagnostic strategy to detect chromosomal abnormalities in fetal and neonatal pathology samples

Double Trisomy 16 and 22 Clinically Mimic Partial Hydatidiform Mole in a Case of Subsequent Pregnancy Loss

A case of double trisomy 16 and 22 in the second pregnancy loss is presented. DNA analyses (short tandem repeats genotyping) of miscarriage specimen was indicated because of ultrasound suspicion of partial hydatidiform mole. After the partial hydatidiform mole exclusion, further DNA analyses focused on the most common aneuploidies causing pregnancy loss, detected double trisomy 16 and 22 in the product of conception. The couple was referred to clinical genetic consultation and normal parental karyotypes were proved. For further explanatory purposes, archived material from the first pregnancy loss was analyzed and trisomy of chromosome 18 was detected. By comparison of allelic profiles of the mother, father, and both losses, the maternal origin of all aneuploidies was proven what can be attributed to frequent meiosis errors, probably due to advanced maternal age (44 years at the first loss and 45 years at the second loss). In conclusion, aneuploidies can mimic partial hydatidiform mole. Genetic analysis is helpful on the one hand to rule out partial hydatidiform mole and on the other hand to identify aneuploidies and in this way to determine the cause of miscarriage.

Detection of Aneuploidies in Products of Conception and Neonatal Deaths in Iranian Patients Using the Multiplex Ligation-Dependent Probe Amplification (MLPA)

Background:

Around 70% of all pregnancies (Including 15% of clinically-recognized ones) are lost due to various fetal or maternal disorders. Chromosomal aneuploidies are among the most common causes of pregnancy loss. Standard chromosome analysis using G-banding technique (Karyotype) is the technique of choice in studying such abnormalities; however, this technique is time-consuming and sensitive, and limited by vulnerabilities such as cell culture failure. The use of molecular cytogenetic techniques, including array-based techniques and Multiplex Ligation-Dependent Probe Amplification (MLPA), has been proposed to overcome the limitations of this method to study the products of conception. This study has been designed to investigate the feasibility of using MLPA technique as a standalone genetic testing, with histopathologic examinations and genetic counseling to detect aneuploidies in products of conception and neonatal deaths.

Methods:

Forty-two verified fetal and neonatal samples were studies and genetic counseling was scheduled for all parents. Histopathologic examinations were carried out on the products of conception, and appropriate fetal tissues were separated for genetic studies. Following DNA extraction and purification, MLPA was carried out to investigate chromosomal aneuploidies.

Results:

Nine samples (21.42%) were diagnosed to be affected with aneuploidy. Detected aneuploidies were trisomy 22 (n=3), trisomy 21(n=1), trisomy 18 (n=2), trisomy 16 (n=1), trisomy 13 (n=1), and monosomy of chromosome X (n=1). The MLPA analysis results were conclusive for all of the fetal samples (Success rate: 100%).

Conclusion:

These results suggest that MLPA, as a standalone genetic testing, is an accurate, rapid, and reliable method in overcoming the limitations of standard cytogenetic techniques in genetic investigation of products of conception.

Chromosomal anomalies in early spontaneous abortions: interphase FISH analysis on 855 FFPE first trimester abortions

OBJECTIVE

Cytogenetic analysis of spontaneous abortuses presents at least two main challenges, cell culture failure, and excess of normal female karyotypes related to maternal cell contamination (MCC). Molecular cytogenetic techniques using uncultured cell suspension overcome cell culture failure, but do not resolve MCC at all. The aim of the present study is to demonstrate that interphase fluorescence in situ hybridization (FISH) on routine formalin-fixed paraffin embedded (FFPE) abortive materials is an efficient method to identify chromosomal anomalies in abortuses and to detect MCC.

METHOD

Interphase FISH with a panel of eight probes was applied on 855 FFPE consecutive early spontaneous abortions.

RESULTS

Male/female ratio was 0.88 in the complete sample, 0.9 in the group of negative FISH result, and 0.8 in the group with abnormal FISH results, suggesting that no gender predominance was present in our data. The aneuploidy rate was 50.3%. Autosomal trisomies were 60%, polyploidies 23.2%, and X monosomy 14%. Chromosomal mosaicism was discovered in 1.9% with six cases of confined placental mosaicism.

CONCLUSION

FISH on FFPE abortion materials appears to be a successful approach to detect chromosomal anomalies in abortions. Moreover, the preservation of the tissue morphology allows the analysis of only the fetal cells, making the presence of maternal tissues irrelevant.

Effects of subtelomeric copy number variations in miscarriages

PURPOSE

This study was performed on miscarriage samples for chromosome analysis to detect copy number variations (CNVs) related to subtelomeric regions, and with these results we aimed to adapt multiplex ligation-dependent probe amplification (MLPA) method for prenatal diagnosis.

MATERIALS AND METHODS

The cell cultures and DNA isolations were performed on 60 miscarriage samples. For maternal contamination analysis, DNA isolations and quantitative fluorescent polymerase chain reactions were done using peripheric blood of mothers who had miscarriages. We compared short tandem repeat peak profiles of miscarriage samples and mothers. The subtelomeric regions of the chromosomes were assessed using the MLPA method.

RESULTS

Of 43 miscarriage samples, 19 had normal karyotype (44.2%), 10 had numerical abnormalities (23.3%), and 2 had structural abnormalities (4.7%). Subtelomeric 16q duplication was determined in 2 of the 30 miscarriage samples investigated with MLPA method (6.6%).

CONCLUSION

There is no statistically significant difference between two groups (p > 0.05). However, the fact that the 6.6% subtelomeric CNV found in miscarriage samples was not found in controls, showed that further studies are required. We recommend that the miscarriage samples of the couples with recurrent miscarriage should be analyzed in terms of subtelomeric CNV after the exclusion of other clinical reasons.

The genetic autopsy

PURPOSE OF REVIEW

To assess the relevance of perinatal and pediatric autopsies in genetic and metabolic diseases.

RECENT FINDINGS

Genetic investigations are an important component of fetal autopsies. Despite the advances in imaging diagnosis, the autopsy can identify abnormalities not seen on ultrasound or MRI, as confirmed in recent comparative studies. This is crucial in the diagnosis of syndromic conditions in which the information may be essential to determine the syndrome. Genetic tests may also have a role in the investigation of intrauterine growth restriction and unexplained stillbirth. New techniques have increased the diagnostic yield, even in cases of macerated fetuses.The genetic autopsy is not limited to fetal loss. Genetic abnormalities underlie many cases presenting as sudden unexpected death in infancy, childhood and adolescence, and the need to obtain appropriate samples for genetic analysis applies not only to fetal autopsies.

SUMMARY

Fetal autopsies are still the gold standard in diagnosis of fetal abnormalities. Genetic studies are an important component, not only in cases of congenital malformations, but also in unexplained intrauterine death and sudden unexpected death in infancy, as well as in children and adults.

Aneuploidy detection in paraffin embedded tissue from products of conception by mini-STR genotyping

Autosomal trisomy is the most common genetic abnormality observed in pregnancy loss. We designed a panel of mini-short tandem repeats (mini-STRs) for aneuploidy detection in chromosomes 13, 16, 18 and 21 from fresh and formalin fixed, paraffin embedded (FFPE) samples from products of conception (POC). FFPE POCs with trisomy 13 (n = 6), trisomy 18 (n = 6), trisomy 21 (n = 12), 6 euploid for the chromosomes of interest and two trisomy 16 samples from fresh tissue were tested. Concordance between cytogenetics and genotyping was 100% for non-mosaic samples. Mini-STR genotyping is a viable method for targeted aneuploidy detection in low quality DNA samples.

Cost-effectiveness of cytogenetic evaluation of products of conception in the patient with a second pregnancy loss

OBJECTIVE

To compare the cost of two strategies for managing the patient with recurrent pregnancy loss (RPL).

DESIGN

Cost analysis using a decision analytic model was used to compare obtaining an evidence-based workup (EBW) for RPL versus obtaining a karyotype of the products of conception (POC) and proceeding with an EBW only in the setting of euploid POC.

SETTING

Outpatient care.

PATIENT(S)

A simulated cohort of patients experiencing a second pregnancy loss.

INTERVENTION(S)

Not applicable.

MAIN OUTCOME MEASURE(S)

Total cost of investigating the cause of RPL after a second pregnancy loss.

RESULT(S)

For all age categories, obtaining a karyotype of POC was less costly than an evidenced-based RPL evaluation. Monte Caro analysis demonstrated a net economic benefit for the karyotype strategy ($4,498 [±$792] vs. $5,022 [±$1,130]).

CONCLUSION(S)

Our model suggests an economic advantage for obtaining a karyotype of POC in women with second miscarriage.