T. Marton

Rapid Trisomy Diagnosis (21, 18, and 13) Using Fluorescent PCR and Short Tandem Repeats: Applications for Prenatal Diagnosis and Preimplantation Genetic Diagnosis

Purpose and Methods:Prenatal diagnosis of fetal trisomies is usually performed by cytogenetic analysis from amniotic fluid. This requires lengthy laboratory procedures and high costs and is unsuitable for large-scale screening of pregnant women. An alternative method, which is rapid and inexpensive and may potentially be suitable for diagnosing trisomies even from single fetal cells, is the fluorescent polymerase chain reaction (F-PCR) using polymorphic small tandem repeats (STRs).Results:In this paper we present data demonstrating that fluorescent PCR amplification of STRs can be used for rapid diagnosis of trisomy 21, trisomy 18, and trisomy 13 and can be successfully applied to both prenatal diagnosis and diagnosis of single cells. This study also reports significant numbers of prenatal diagnoses using quantitative fluorescent PCR.Conclusions:We believe that further studies of greater numbers of samples will determine the absolute reliability of this technique. These results also provide a model for trisomy diagnosis from single cells using multiple STR markers for either preimplantation genetic diagnosis or, potentially, diagnosis from fetal cells isolated from maternal blood.

Prenatal detection of trisomy 21 and 18 from amniotic fluid by quantitative fluorescent polymerase chain reaction.

Prenatal diagnosis of fetal trisomies is usually performed by cytogenetic analysis on amniotic fluid. This requires lengthy laboratory procedures and high costs, and is unsuitable for large scale screening of pregnant women. An alternative method, which is both rapid and inexpensive and suitable for diagnosing trisomies even from single fetal cells, is the fluorescent polymerase chain reaction using polymorphic small tandem repeats (STRs). In this paper we present the preliminary results of a larger study comparing parallel prenatal diagnoses of trisomies 21 and 18 using cytogenetics with quantitative fluorescent polymerase chain reaction using STR markers. The results obtained by the two techniques were concordant in all cases. This is the first study reporting significant numbers of prenatal diagnoses using the quantitative fluorescent polymerase chain reaction. We believe that further studies on greater numbers of samples will determine the absolute reliability of this technique. These results also provide a model for diagnosis of trisomy from single fetal cells isolated from maternal blood.

Ivemark syndrome with asplenia in siblings

We describe two siblings with Ivemark syndrome. In both cases, absent spleen, symmetric liver, and lungs with three lobes were associated with complex cardiac malformation. The syndrome was diagnosed prenatally in the second case by fetal echocardiography at the twentieth week of pregnancy. The autosomal recessive mode of inheritance of Ivemark syndrome is further supported by these cases.

Calcification of the fetal heart - Four case reports and a literature review

Calcification of the heart and vessels in fetuses is a rare condition. It may be dystrophic or metastatic. An extremely rare form of vascular calcification has been termed ‘idiopathic arterial calcification of infancy’, which is inherited in an autosomal recessive pattern. We report four cases of myocardial calcifications of different origin diagnosed in utero. The correct diagnosis is very important in regard to genetic counselling. Copyright

Prenatal diagnosis of abnormal course of umbilical vein and absent ductus venosus--report of three cases.

An abnormal course of the umbilical vein is a rare anomaly. Its association with the congenital absence of the ductus venosus is common. We found 3 cases of an abnormal course of the umbilical vein and an absent ductus venosus. In 2 of these cases, the umbilical vein turned down and continued in the internal iliac vein, and no ductus venosus was found. One of these pregnancies was terminated. From the continued pregnancy a growth-retarded baby was born. At follow-up examinations, mild microcephaly, mildly elevated levels of ammonia, delayed speech and mild muscular hypotonia were found. In the third case, the umbilical vein turned up from the level of umbilical ring and the anterior of the liver above the diaphragma and connected directly into the right atrium. Associated complex congenital heart malformations – transposition of the great arteries, and ventricular septal defect – were diagnosed prenatally. In the umbilical vein from the placenta to the umbilical ring, the flow was low velocity continuous; from the umbilical ring to the right atrium, the flow was biphasic high velocity (90 cm/s). Such an elevated blood flow could be a sign of increased cardiac preload. The long-term neurological follow-up of babies with prenatally diagnosed venous malformations is necessary.

Prenatal detection of trisomy 13 from amniotic fluid by quantitative fluorescent polymerase chain reaction

Prenatal diagnosis of fetal trisomies is usually performed by cytogenetic analysis from amniotic fluid. However, this requires lengthy laboratory procedures, high costs and is unsuitable for large‐scale screening of pregnant women. An alternative method, which is rapid, inexpensive and suitable for diagnosing trisomies, even from single fetal cells, is the fluorescent polymerase chain reaction (PCR) using polymorphic small tandem repeats (STRs). In this paper, we present the method of rapid prenatal detection of trisomy 13 from amniotic fluid using fluorescent PCR and two highly polymorphic STRs (D13S258 and D13S631). The results obtained by quantitative fluorescent PCR amplification of fetal DNA were concordant with amniocyte karyotyping results in all cases. Two cases of trisomy 13 were detected from 212 amniotic fluids and the results obtained from D13S631 and D13S258 amplification are presented. In the first trisomy 13 case, a triallelic pattern was detected by both markers, and in the second case, D13 markers showed a characteristic 2:1 dosage allele ratio, both of which demonstrate trisomy 13 status. All other heterozygous disomic samples showed an allele intensity ratio of 1:1.

Congenital Heart Diseases in Twin Pregnancies

Objective: To find connection between the type of congenital heart malformations and twin pregnancies. Method: Retrospective analysis of data of fetal cardiology database between 1 January 1996 and 30 November 2003. Results: In single pregnancies 455 and in twin pregnancies 31 severe congenital heart malformations were diagnosed prenatally. In monozygotic twin pregnancies 36% of heart malformations were pulmonary stenosis and 45% endocardial fibroelastosis, which is significantly higher than in single pregnancies. In dizygotic twin pregnancies Ebstein malformation was significantly more frequent than in single pregnancies. With the exception of Ebstein malformation in dichorionic and dizygotic twin pregnancies the cardiac malformations were similar to the ones in single pregnancies. Conclusions: The twin pregnancy alone can be considered as indication for fetal echocardiography. The type of congenital heart malformations detected in monochorial twin pregnancies was different from those found in single, dizygotic or dichorionic twin pregnancies. Chorionicity seems to be more important than zygosity.

Multifocal hemangioendothelioma of the fetus and placenta.

A case of multifocal hemangioendothelioma of the liver, adrenal gland, and placenta is reported. The histological appearance of the tumor is consistent with an infantile hemangioendothelioma, type 2. Multifocal development is the most obvious explanation for the disease but the possibility that this represents malignant placental neoplasm with metastases requires consideration.

Implementation and Experience of an Alternative QF-PCR and MLPA Diagnostic Strategy to Detect Chromosomal Abnormalities in Fetal and Neonatal Pathology Samples

Chromosomal abnormalities are a significant cause of pregnancy loss. Solid tissue fetal and neonatal pathology samples are routinely examined by karyotype analysis after cell culture. However, there is a high failure rate, and this approach is expensive and labor intensive. We have therefore evaluated a new molecular strategy involving quantitative fluorescent polymerase chain reaction (QF-PCR) and subtelomere multiplex ligation-dependent probe amplification (MLPA) analysis. A retrospective audit showed that less than 4% of abnormal cases may not be detected by this molecular strategy. We validated this strategy in parallel with cytogenetic analysis on 110 patient samples, which included cases of fetal loss, still birth, neonatal death, termination of pregnancy, recurrent miscarriage, and sudden unexpected death in infancy. This validation showed that 55 of the 57 samples that gave a result for both strategies were concordant. During the 1st year of diagnostic testing, we analyzed 382 samples by the molecular strategy. A 16% abnormality rate was observed. These included trisomies 13, 18, 21, monosomy X, and triploidy detected by QF-PCR (77%), and 23% were other trisomies and subtelomere imbalances detected by MLPA. This strategy had a 92% success rate in contrast to the 20%-30% failure rate observed with cell culture and cytogenetic analysis. We conclude that QF-PCR and subtelomere MLPA is a suitable strategy for analysis of the majority of fetal and neonatal pathology samples, with many advantages over conventional cytogenetic analysis.

Polysplenia and situs inversus in siblings. Case reports.

Heterotaxy syndromes, otherwise laterality defects, are variations from anatomic left-right asymmetry. Situs inversus is the complete reversal of the normal situs, still situs ambiguus is the randomisation of the normal organ position. Situs ambiguus may be manifested as asplenia or polysplenia syndrome. Normal situs and both types of the heterotaxy syndromes may appear among some affected families, whereas the different situs are rarely expressed in the same family. We describe an autosomal-recessive inherited familial heterotaxy syndrome with two affected siblings – one of whom has situs inversus, and the other with polysplenia syndrome. The polysplenia syndrome was diagnosed by fetal echocardiography. Since the chromosomal or molecular diagnosis of laterality defects are accessible only in X-linked heterotaxy syndromes, the fetal echocardiography is the earliest available diagnostic method in this field. Therefore, fetal echocardiography has great importance for affected families.