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Incorporating utility-based quality-of-life assessment measures in clinical trials. Two examples.

The utility approach to the measurement of health-related quality of life is discussed and its theoretical foundations and compatibility with economic evaluation are explained. The advantages of the approach include its generalizability, comprehensiveness, ability to integrate mortality and morbidity effects, ability to represent multiple viewpoints, and its incorporation of time and risk preferences in the scores. Disadvantages include interviewer administration, limitations on obtaining scores from all types of subjects, some lack of precision, and attenuated clinical sensibility. Use of the utility approach as an outcome measure in two recent clinical trials is also described. In a trial of an oral gold compound for arthritis, the utility measures were responsive and added information to that from standard clinical and other quality-of-life measures. The utility approach and clinical decision making are being used in an on-going trial of two procedures for prenatal diagnosis in which major potential differences include quality-of-life effects. The comprehensiveness of the utility approach overcomes difficulties in interpreting results from more narrowly focused psychosocial measures of outcome. In sum, the utility model provides a reliable, valid, and responsive approach to measuring quality of life as an outcome in clinical trials.

Adult↗

Clinical teratology.

Genetic causes account for 20% to 25% of human birth defects, but the largest proportion of birth defects have no definitive etiology and some of these malformations may be due to intrinsic, "nonpreventable" spontaneous errors of development. Environmental causes, which include maternal disease states, maternal infection, mechanical factors, problems of constraint, chemicals, drugs, and physical agents, are responsible for only about 10% of human birth defects. The scientific basis for understanding the risk of congenital malformations from exposure to environmental agents is based on several tenets of toxicology and embryology dogma. The first tenet is that essentially all teratogens that have been studied have a typical toxicologic dose response relationship and a no-effect dose. Secondly, the stage of gestation is critical to the effects that are expected, and all stages of embryogenesis and fetogenesis can have vulnerability to environmental toxicants. Thirdly, the response of the embryo and fetus is characteristic for each teratogenic agent, although there is some similarity in the effect of certain teratogens. Appropriately designed developmental toxicology studies and basic embryologic and biologic concepts are all used to estimate the potential reproductive hazard for embryonic death, growth retardation, congenital malformation, and functional deficit.

Abnormalities, Drug-Induced↗

Prenatal exclusion of severe factor VII deficiency.

A nonconsanguineous asymptomatic couple, were identified as carriers of factor VII (FVII) deficiency when two of their newborn children died of massive intracranial hemorrhage secondary to severe congenital FVII deficiency. Complete sequence analysis of the factor VII (F7) gene in this couple indicated that the mother was heterozygous for an A to G transition at position -2 of the exon 5 acceptor splice site, and the father was heterozygous for a G to T transversion at position +1 of the exon 6 donor splice site. This information allowed us to exclude a compound heterozygous deficiency state in a subsequent pregnancy using PCR/direct sequencing of the F7 gene using DNA obtained from chorionic villi at 10 weeks' gestation. Our experience with the family reported here further supports the conclusion that mutation-specific detection is reliable in the prenatal exclusion of severe bleeding disorders.

Chorionic Villi Sampling↗

Protein and DNA analysis for the prenatal diagnosis of alpha2-laminin-deficient congenital muscular dystrophy.

Congenital muscular dystrophies (CMD) are characterized by neonatal hypotonia and/or artrogriposis associated with a dystrophic muscle biopsy. The CMD1A form is caused by a deficiency of the alpha2 chain of laminin 2 (LAMA2 gene at 6q2), a protein present in the basal lamina of muscle fibers, in Schwann cells, epidermis, and in fetal trophoblastic tissue. This allows its study for prenatal diagnosis in the chorionic villous (CV), which was performed in a family with one deceased affected CMD1A child. Immunohistochemical analysis of the CV using antibodies against the C- and N-terminal domains of the alpha2-laminin protein showed a normal positive labeling for both antibodies in the "at-risk" CV, which did not differ from the normal control CV. The integrity of the CV membrane was confirmed through the analysis with antibodies against alpha1, beta1, and gamma1 laminins. DNA study using markers flanking the 6q2 region showed that the affected patient and the "at-risk" fetus did not share the same haplotype. Therefore, the fetus was considered normal through both methodologies, which was confirmed after the birth of a clinically normal male baby. As the LAMA2 gene is very large and the spectrum of mutations causing disease is wide, the analysis of the protein in muscle biopsy has been largely used for the diagnosis. Besides, the possibility to detect it in the chorionic villous, mainly using positive markers, also offers a powerful tool for prenatal diagnosis.

Antibodies, Monoclonal↗

Prenatal diagnosis of mosaic trisomy 20 in New Zealand.

OBJECTIVE: Mosaic trisomy 20 is not an uncommon finding on amniocentesis or CVS. Unlike other mosaic aneuploidies it is a relatively benign abnormality which, along with a lack of long-term follow-up of cases, has led to uncertainty when counselling parents. We aimed to identify known mosaic trisomy 20 pregnancies in New Zealand in the last 10 years and document their outcome. DESIGN: Retrospective database review with prospective clinical follow-up. METHODS: Cases were identified from the databases of the two clinical genetic services, as well as the four regional cytogenetics laboratories. Medical records were reviewed and where patients were available they were offered follow-up. RESULTS: Fourteen cases were identified (13 on amniocentesis, one on CVS), all with low levels of mosaicism (8-50%). In 12 cases, the children were physically and developmentally normal, with the longest follow-up being 10 years. Minor anomalies were noted in two cases. There were no major malformations noted in any of the cases and where repeat karyotypes were performed on blood or urine cytology these were normal. CONCLUSIONS: This series confirms a much lower incidence of phenotypic abnormalities associated with mosaic trisomy 20 compared to other forms of mosaic aneuploidy. Attempts to predict which of these pregnancies will have poor outcomes have not proven to be reliable. We recommend that, if a detailed anatomy scan is normal, parents be counselled that the risk of abnormality is less than 10%. Further tests should be performed only on the basis of a clinical indication.

Adult↗

Nuclear and chromosomal replication patterns in chorionic villi cells by bromodeoxyuridine labelling and DNA flow cytometry.

Cell kinetics of chorionic villi (CV) were studied by BrdUrd-incorporation detected by fluorescence-plus-Giemsa and BrdUrd-antibody techniques, and by DNA flow cytometry. Growth characteristics of long-term cultures of CV resembled fibroblasts with a total cell cycle time of 26 h, final S phase of 9 h, penultimate S phase of 16 h and G2/M phase of 3-4 h. Especially useful for a quick routine diagnostic approach, Ultroser RG, a commercially available serum supplement, significantly increased cell proliferation and stabilized cell cycle lengths to a total cell cycle time of 14 h, final S phase of 7 h, penultimate S phase of 6 h and G2/M phase of 4 h. Moreover, mitotic activity steadily increased in cultured CV, when studying six successive subculturings. This reflects adaptation to the culture conditions rather than an inherent response of cultured CV cells of increasing passage numbers. Native villi exposed to BrdUrd immediately after biopsy show lower rates of uptake than do aliquots after overnight incubation. As shown by BrdUrd-pulse labelling studies, more than 7 h are required to overcome the proposed 'biopsy stress'. This correlates with routine diagnostic techniques, in which many more metaphase cells are observed in short-term cultures than in direct preparations.

Bromodeoxyuridine↗

First-trimester diagnosis of metachromatic leucodystrophy.

Two pregnancies at risk for late infantile metachromatic leucodystrophy were monitored by assaying arylsulphatase A at 0 degrees C in homogenates of chorionic villi. In one, the very low activity recorded indicated the fetus to be affected, and this was confirmed by demonstration of low arylsulphatase A activity in cultured villi and cultured fetal fibroblasts after termination. In the other pregnancy, normal activity was found in the villi and the pregnancy is continuing. This simple chromogenic assay appears to be reliable for first-trimester diagnosis of metachromatic leucodystrophy. However, there is a probability of mis-diagnosis if the standard assay at 37 degrees C is used.

Adult↗

Prenatal diagnosis in Pelizaeus-Merzbacher disease using RFLP analysis.

Pelizaeus-Merzbacher disease (PMD) is a rare X-linked recessive disorder with severe psychomotor retardation and neurological symptoms due to an inborn abnormality of proteolipid protein (PLP), the major protein component of myelin. A tight linkage between the gene of PLP and PMD locus has been suggested. We have carried out a series of RFLP studies using a cDNA probe for PLP and an anonymous DNA-fragment DXYS12 in a large Finnish family with at least three affected individuals. DNA analysis on chorionic villus specimens allowed us to exclude the disease in a male fetus of a possible carrier mother and, likewise, to demonstrate carrier status in a female fetus in another at-risk pregnancy.

Adolescent↗

An evaluation of 75 terminations of pregnancy based on abnormal laboratory findings at first trimester CVS.

Seventy-five selective terminations, based on abnormal laboratory findings at first-trimester CVS, were performed in 1581 consecutive pregnancies. In all cases a (semi-) direct method of cytogenetic analysis was used. The 75 abortions were analysed in number of ways. Confirmatory studies showed that three cases had to be considered as false-positive findings, and in one other case the results were inconclusive. Based on literature data, it was estimated that 41 of the 75 pregnancies would have resulted in seriously handicapped children, surviving beyond the age of 1 year, if no termination of pregnancy had taken place. Negative side-effects of the procedure include: spontaneous abortion of chromosomally normal fetuses due to the CVS procedure itself and the need for a number of secondary amniocenteses (5.1%). The advantage of DNA diagnosis in X-linked diseases is illustrated by comparing the CVS results with a previously published amniocentesis study.

Abortion, Eugenic↗

Fetal hydrops in Sardinia: implications for genetic counselling.

This paper describes the first case of Hb Bart's hydrops fetalis syndrome in the Sardinian population. Despite the high frequency of a-thalassemia, fetal hydrops is extraordinarily rare in the Sardinian population because a-thalassemia is more usually the result of the single a-thalassemia globin gene deletion and is very rarely produced by the deletion of two a-globin genes. The fetus, the product of a consanguineous marriage at risk for beta-thalassemia, was monitored by chorionic villi DNA analysis which detected the heterozygous state for the codon 39 nonsense mutation. Follow-up ultrasound examination showed fetal hydrops, which led us to carry out further investigation. Hemoglobin and a-globin gene analysis on cord blood obtained by cordocentesis revealed the homozygous state for the most common deletion ao-thalassemia in Mediterranean populations. Retrospective evaluation of the father's hematological features showed very low MCH-MCV for a beta-thalassemia carrier which may indicate co-inherited a-thalassemia. These findings indicate that careful evaluation of red cell indices of parents at risk for beta-thalassemia and adequate consideration of the consanguinity may point to co-inherited a-thalassemia and lead to the appropriate analysis.

Chorionic Villi Sampling↗

A cost-benefit analysis of prenatal diagnosis by amniocentesis in Denmark.

A cost-benefit analysis of amniocentesis has been performed using both the excess-cost- and the replacement methods and several replacement and discount rates. In Denmark, amniocentesis is offered free of charge to various groups of pregnant women at risk for genetic disorders of the foetus. Most important is age greater than or equal to 35 years. The analysis is based on incidence and survival rates for Down syndrome (trisomy 21), Patau's syndrome (trisomy 13) and Edward's syndrome (trisomy 18), and on incidence and survival rates of children with neural tube defects. If amniocentesis were offered to all pregnant women independent of age, with a supposed participation rate of 75% and if only tangible costs and benefits were included, the analysis shows a benefit:cost ratio greater than 1.0 using discount rates of 4% and 7% (both for the excess-cost- and replacement method); a benefit:cost ratio less than 1.0 is found using 10%. The ratio is approximately 1.0, if pregnant women aged 15-19 and 20-24 years are excluded, using the discount rate 10%. Calculations for other participation rates have also been performed. If intangible costs and benefit are included, the results are uncertain.

Adult↗

X-linked lymphoproliferative disease: prenatal detection of an unaffected histocompatible male.

Chorionic Villous Biopsy (CVS) for diagnosis of XLP was undertaken at 10 weeks gestation in an obligate carrier. The fetus was found to be male by cytogenetic analysis. XLP (Xq25-q26) is closely linked to the RFLP markers DXS10, DXS37 and DXS42, but only DXS10 (distal to XLP) was informative for prenatal diagnosis in this family. RFLP analysis using this marker gave a 7% risk that the fetus was affected, based on the known recombination frequency between DXS10 and XLP. Further investigation was then undertaken to obtain a rapid and more accurate diagnosis using the three highly polymorphic PCR based markers. These were the AC repeat markers DXS424 (XL5A) and DXS425 (XL90A3) and the tetramer repeat marker within HPRT. DX425 is approximately 10 cM proximal to DXS10 and HPRT but is not known with certainty to map proximal or distal to XLP. DXS424 is proximal to DXS10 and HPRT and was inferred to be proximal to XLP on the basis of map distance from HPRT estimated by linkage analysis of data from CEPH pedigrees. This was confirmed by a recombinant in the XLP family between DXS424 and DXS425, placing DXS424 proximal to XLP. Diagnosis by linkage using DXS424 and DXS425, at least one of which is proximal to XLP, and distal markers DXS10 and HPRT, increased the accuracy of diagnosis using flanking marker analysis to greater than 99% that the fetus was unaffected. HLA DR typing of the CVS showed that the fetus was DR identical to a male sibling with XLP. HLA compatibility was confirmed at delivery by full HLA typing and MLC.(ABSTRACT TRUNCATED AT 250 WORDS)

Child, Preschool↗

Prenatal diagnosis of fragile X syndrome by direct detection of the dynamic mutation due to an unstable DNA sequence.

The fragile X syndrome is the most common familial form of mental retardation. The mutation causing the syndrome is dynamic mutation due to an unstable DNA (CCG)n repeat localized at Xq27.3. We have previously reported a PCR procedure to prepare a diagnostic probe, pPCRfx1, which can be used to determine the genotype of fragile X mutation individuals by Southern blot analysis. In the present study, pPCRfx1 was applied to the prenatal diagnosis, using chorionic villus cells, of a fetus which was at risk of having fragile X syndrome. In the PstI assay, the Southern blot showed the typical pattern of a female carrier with the full mutation. Analysis of the DNA methylation patterns by EcoRI + EagI assay showed that the EagI restriction site was not methylated on the mutated X chromosome of chorionic villi, but the sites were totally methylated in the brain and other tissues of the fetus. Thus the fetus was diagnosed to be a heterozygous female carrier of the dynamic mutation involved in the fragile X syndrome.

Blotting, Southern↗