A case of triploidy

Prenatal diagnosis of triploidy in second trimester of pregnancy: a series of 4 cases over an eleven-year period / Diagnosticul prenatal al triploidiei în trimestrul al II-lea de sarcină: o serie de patru cazuri depistate în unsprezece ani

Triploidy is a numerical chromosomal anomaly characterized by the presence of three sets of haploid chromosomes. The incidence is hard to evaluate, because usually it causes 1st trimester miscarriage. At 20 weeks of amenorrhea the incidence of triploidy is estimated at 1/250,000 cases. We present 4 cases of triploidy diagnosed during the decade 2003-2013 in the Prenatal Diagnosis Department of Maternity “Cuza-Vodă” Iasi, Romania, all registered in one year. The analysis of pathological cases identified in the last 11 years by prenatal diagnosis has shown that triploidies represented only 5.7% of numeric chromosomal anomalies, but in 2013 the four cases of triploidy represented 36% of numeric chromosomal anomalies. The karyotypes were recommended after discovering different congenital anomalies by ultrasound scan. In all cases, an intrauterine growth retardation (IUGR) was present but with no placental changes. Also, we discovered anomalies of limbs, congenital anomalies of heart and some dysmorphic features. This series demonstrates that triploidy may be discovered in the 2nd trimester of pregnancy and has a heterogeneous aspect at ultrasound scan, which can generate diagnostic difficulties. Therefore, the detection by ultrasound scan, at 18-22 weeks of pregnancy, of complex foetal morphological abnormalities should be an important reason for amniocentesis to search chromosomal anomalies

Partial molar pregnancy after intracytoplasmic sperm injection occurring as a result of diploid sperm usage

PURPOSE

Partial molar pregnancies are rare conceptions characterized by having 69 rather than 46 chromosomes, the additional chromosome complement usually occurring as a result of fertilization of the ovum by two sperm. Although assisted conception with intracytoplasmic sperm injection (ICSI) should prevent the development of a partial molar pregnancy, occasional cases have been described after assisted conception using ICSI. The objective of this study was to investigate the cause of partial molar pregnancy in a couple who had undertaken assisted conception with ICSI.

METHODS

Fluorescent microsatellite genotyping of DNA from the couple and tissue from their partial molar pregnancy was performed in order to confirm diagnosis and investigate the origin of the additional chromosome set.

RESULTS

Genotyping confirmed that the partial molar tissue was triploid with an additional chromosome complement from the father. Genotyping of additional loci proximal to the centromere demonstrated that the two paternal sets of chromosomes originated in a single sperm with a double complement of paternal DNA resulting from non-reduction at the second meiotic division.

CONCLUSIONS

This study confirms that partial molar pregnancy may occur after assisted conception with ICSI and that this occurs as a result of fertilization with a diploid sperm.

The biology of infertility: research advances and clinical challenges

Reproduction is required for the survival of all mammalian species, and thousands of essential 'sex' genes are conserved through evolution. Basic research helps to define these genes and the mechanisms responsible for the development, function and regulation of the male and female reproductive systems. However, many infertile couples continue to be labeled with the diagnosis of idiopathic infertility or given descriptive diagnoses that do not provide a cause for their defect. For other individuals with a known etiology, effective cures are lacking, although their infertility is often bypassed with assisted reproductive technologies (ART), some accompanied by safety or ethical concerns. Certainly, progress in the field of reproduction has been realized in the twenty-first century with advances in the understanding of the regulation of fertility, with the production of over 400 mutant mouse models with a reproductive phenotype and with the promise of regenerative gonadal stem cells. Indeed, the past six years have witnessed a virtual explosion in the identification of gene mutations or polymorphisms that cause or are linked to human infertility. Translation of these findings to the clinic remains slow, however, as do new methods to diagnose and treat infertile couples. Additionally, new approaches to contraception remain elusive. Nevertheless, the basic and clinical advances in the understanding of the molecular controls of reproduction are impressive and will ultimately improve patient care.

Mechanisms giving rise to triploid zygotes during assisted reproduction

OBJECTIVE

To review information on the origin of triploid zygotes as gathered from assisted reproduction techniques.

DESIGN

Identification of relevant literature by a MEDLINE search and own experience on the basis of cytogenetic studies of abnormally fertilized oocytes.

SETTING

None.

PATIENT(S)

None.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

None.

RESULT(S)

Penetration of two haploid spermatozoa or of a single diploid spermatozoon into the oocyte causes diandric triploidy. The first case can be discerned by formation of a total of three pronuclei, whereas the second process will remain undetected, because it involves a female and a single but diploid male pronucleus. Digynic triploidy after intracytoplasmic sperm injection is characterized by nonextrusion of the second polar body and formation of three pronuclei. Digyny can also result from the fertilization of diploid giant oocytes. Depending on how maturation of these gametes proceeds, three or only two pronuclei will be observed. Thus, the size of the pronuclear stage must be considered for a successful identification of the abnormality. Endoreduplication within the female pronucleus is not detectable and may represent another, albeit rare, origin of digynic triploidy.

CONCLUSION(S)

Routine inspection of the number of pronuclei is not an absolutely reliable tool for excluding the development of triploid embryos. Observations during assisted reproduction may yield valuable information on the origin of triploidy.