Risk Assessment for Huntington's Disease for (Future) Offspring Requires Offering Preconceptional CAG Analysis to Both Partners.

Amongst the main reasons people at risk for Huntington's disease (HD) have for undergoing predictive genetic testing are planning a family and prevention of passing on an expanded CAG-repeat to future offspring. After having received an unfavourable test result, a couple may consider prenatal testing in the foetus or preimplantation genetic diagnostic testing (PGD) in embryos. Testing of the foetus or embryos is possible by means of direct testing of the expanded repeat.

Clinical and genetic characteristics of late-onset Huntington's disease.

Background: The frequency of late-onset Huntington's disease (>59 years) is assumed to be low and the clinical course milder. However, previous literature on late-onset disease is scarce and inconclusive.

Objective: Our aim is to study clinical characteristics of late-onset compared to common-onset HD patients in a large cohort of HD patients from the Registry database.

PGD for the m.14487 T>C mitochondrial DNA mutation resulted in the birth of a healthy boy.

We report on the first PGD performed for the m.14487 T>C mitochondrial DNA (mtDNA) mutation in the MT-ND6 gene, associated with Leigh syndrome. The female carrier gave birth to a healthy baby boy at age 42.

Serum AMH levels in healthy women from BRCA1/2 mutated families: are they reduced?

Study Question: Do BRCA1/2 mutation carriers have a compromised ovarian reserve compared to proven non-carriers, based on serum anti-Müllerian hormone (AMH) levels?

Summary Answer: BRCA1/2 mutation carriers do not show a lower serum AMH level in comparison to proven non-carriers, after adjustment for potential confounders.

What Is Known Already: It has been suggested that the BRCA genes play a role in the process of ovarian reserve depletion, although previous studies have shown inconsistent results regarding the association between serum AMH levels and BRCA mutation status. Hence, it is yet unclear whether BRCA1/2 mutation carriers may indeed be at risk of a reduced reproductive lifespan.

Uptake of prenatal diagnostic testing for retinoblastoma compared to other hereditary cancer syndromes in the Netherlands.

Since the 1980s the genetic cause of many hereditary tumor syndromes has been elucidated. As a consequence, carriers of a deleterious mutation in these genes may opt for prenatal diagnoses (PND). We studied the uptake of prenatal diagnosis for five hereditary cancer syndromes in the Netherlands.

De novo mtDNA point mutations are common and have a low recurrence risk.

Background: Severe, disease-causing germline mitochondrial (mt)DNA mutations are maternally inherited or arise de novo. Strategies to prevent transmission are generally available, but depend on recurrence risks, ranging from high/unpredictable for many familial mtDNA point mutations to very low for sporadic, large-scale single mtDNA deletions. Comprehensive data are lacking for de novo mtDNA point mutations, often leading to misconceptions and incorrect counselling regarding recurrence risk and reproductive options.

Preventing the transmission of mitochondrial DNA disorders using prenatal or preimplantation genetic diagnosis.

Mitochondrial disorders are among the most common inborn errors of metabolism; at least 15% are caused by mitochondrial DNA (mtDNA) mutations, which occur de novo or are maternally inherited. For familial heteroplasmic mtDNA mutations, the mitochondrial bottleneck defines the mtDNA mutation load in offspring, with an often high or unpredictable recurrence risk. Oocyte donation is a safe option to prevent the transmission of mtDNA disease, but the offspring resulting from oocyte donation are genetically related only to the father.

Advantages and Disadvantages of Different Implementation Strategies of Non-Invasive Prenatal Testing in Down Syndrome Screening Programmes.

Background: Implementation of non-invasive prenatal testing (NIPT) in Down syndrome screening programmes requires health policy decisions about its combination with other tests and its timing in pregnancy.

Aim: Our aim was to aid health policy decision makers by conducting a quantitative analysis of different NIPT implementation strategies.

Methods: Decision trees were created to illustrate all plausible alternatives in a theoretical cohort of 100,000 pregnant women in five screening programmes: classical screening by the first-trimester combined test (FCT), pre-selection of high-risk women prior to NIPT by the FCT, NIPT as the first screening test at 10 weeks and at 13 weeks, and the simultaneous conductance of NIPT and the FCT.

Phenotypic and molecular insights into CASK-related disorders in males.

Background: Heterozygous loss-of-function mutations in the X-linked CASK gene cause progressive microcephaly with pontine and cerebellar hypoplasia (MICPCH) and severe intellectual disability (ID) in females. Different CASK mutations have also been reported in males. The associated phenotypes range from nonsyndromic ID to Ohtahara syndrome with cerebellar hypoplasia.

Hereditary breast and ovarian cancer and reproduction: an observational study on the suitability of preimplantation genetic diagnosis for both asymptomatic carriers and breast cancer survivors.

Preimplantation genetic diagnosis (PGD) is a reproductive option for BRCA1/2 mutation carriers wishing to avoid transmission of the predisposition for hereditary breast and ovarian cancer (HBOC) to their offspring. Embryos obtained by in vitro fertilisation (IVF/ICSI) are tested for the presence of the mutation. Only BRCA-negative embryos are transferred into the uterus.

Evidence for increased SOX3 dosage as a risk factor for X-linked hypopituitarism and neural tube defects.

Genomic duplications of varying lengths at Xq26-q27 involving SOX3 have been described in families with X-linked hypopituitarism. Using array-CGH we detected a 1.1 Mb microduplication at Xq27 in a large family with three males suffering from X-linked hypopituitarism.

An FBN1 deep intronic mutation in a familial case of Marfan syndrome: an explanation for genetically unsolved cases?

Marfan syndrome (MFS) is caused by mutations in the FBN1 (fibrillin-1) gene, but approximately 10% of MFS cases remain genetically unsolved. Here, we report a new FBN1 mutation in an MFS family that had remained negative after extensive molecular genomic DNA FBN1 testing, including denaturing high-performance liquid chromatography, Sanger sequencing, and multiplex ligation-dependent probe amplification. Linkage analysis in the family and cDNA sequencing of the proband revealed a deep intronic point mutation in intron 56 generating a new splice donor site.

PLS3 mutations in X-linked osteoporosis with fractures.

Plastin 3 (PLS3), a protein involved in the formation of filamentous actin (F-actin) bundles, appears to be important in human bone health, on the basis of pathogenic variants in PLS3 in five families with X-linked osteoporosis and osteoporotic fractures that we report here. The bone-regulatory properties of PLS3 were supported by in vivo analyses in zebrafish. Furthermore, in an additional five families (described in less detail) referred for diagnosis or ruling out of osteogenesis imperfecta type I, a rare variant (rs140121121) in PLS3 was found.

Microarrays as a diagnostic tool in prenatal screening strategies: ethical reflection.

Genomic microarray analysis is increasingly being applied as a prenatal diagnostic tool. Microarrays enable searching the genome at a higher resolution and with higher sensitivity than conventional karyotyping for identifying clinically significant chromosomal abnormalities. As yet, no clear guidelines exist on whether microarrays should be applied prenatally for all indications or only in selected cases such as ultrasound abnormalities, whether a targeted or genome-wide array should be used, and what these should include exactly.

Brain white matter oedema due to ClC-2 chloride channel deficiency: an observational analytical study.

Background: Mutant mouse models suggest that the chloride channel ClC-2 has functions in ion and water homoeostasis, but this has not been confirmed in human beings. We aimed to define novel disorders characterised by distinct patterns of MRI abnormalities in patients with leukoencephalopathies of unknown origin, and to identify the genes mutated in these disorders. We were specifically interested in leukoencephalopathies characterised by white matter oedema, suggesting a defect in ion and water homoeostasis.

PGD for hereditary breast and ovarian cancer: the route to universal tests for BRCA1 and BRCA2 mutation carriers.

Preimplantation Genetic Diagnosis (PGD) is a method of testing in vitro embryos as an alternative to prenatal diagnosis with possible termination of pregnancy in case of an affected child. Recently, PGD for hereditary breast and ovarian cancer caused by BRCA1 and BRCA2 mutations has found its way in specialized labs. We describe the route to universal single-cell PGD tests for carriers of BRCA1/2 mutations.

Preimplantation genetic diagnosis in mitochondrial DNA disorders: challenge and success.

Background: Mitochondrial or oxidative phosphorylation diseases are relatively frequent, multisystem disorders; in about 15% of cases they are caused by maternally inherited mitochondrial DNA (mtDNA) mutations. Because of the possible severity of the phenotype, the lack of effective treatment, and the high recurrence risk for offspring of carrier females, couples wish to prevent the transmission of these mtDNA disorders to their offspring. Prenatal diagnosis is problematic for several reasons, and concern the often poor correlation between mutation percentages and disease severity and the uncertainties about the representativeness of a fetal sample.

Structural and functional cardiac changes in myotonic dystrophy type 1: a cardiovascular magnetic resonance study.

Background: Myotonic dystrophy type 1 (MD1) is a neuromuscular disorder with potential involvement of the heart and increased risk of sudden death. Considering the importance of cardiomyopathy as a predictor of prognosis, we aimed to systematically evaluate and describe structural and functional cardiac alterations in patients with MD1.

Methods: Eighty MD1 patients underwent physical examination, electrocardiography (ECG), echocardiography and cardiovascular magnetic resonance (CMR).

An urgent need for a change in policy revealed by a study on prenatal testing for Duchenne muscular dystrophy.

Prenatal diagnosis for Duchenne muscular dystrophy (DMD) was introduced in the Netherlands in 1984. We have investigated the impact of 26 years (1984-2009) of prenatal testing. Of the 635 prenatal diagnoses, 51% were males; nearly half (46%) of these were affected or had an increased risk of DMD.

Mutations in ISPD cause Walker-Warburg syndrome and defective glycosylation of α-dystroglycan.

Walker-Warburg syndrome (WWS) is an autosomal recessive multisystem disorder characterized by complex eye and brain abnormalities with congenital muscular dystrophy (CMD) and aberrant a-dystroglycan glycosylation. Here we report mutations in the ISPD gene (encoding isoprenoid synthase domain containing) as the second most common cause of WWS. Bacterial IspD is a nucleotidyl transferase belonging to a large glycosyltransferase family, but the role of the orthologous protein in chordates is obscure to date, as this phylum does not have the corresponding non-mevalonate isoprenoid biosynthesis pathway.

The clinical and pathological phenotype of C9ORF72 hexanucleotide repeat expansions.

There is increasing evidence that frontotemporal dementia and amyotrophic lateral sclerosis are part of a disease continuum. Recently, a hexanucleotide repeat expansion in C9orf72 was identified as a major cause of both sporadic and familial frontotemporal dementia and amyotrophic lateral sclerosis. The aim of this study was to investigate clinical and neuropathological characteristics of hexanucleotide repeat expansions in C9orf72 in a large cohort of Dutch patients with frontotemporal dementia.

Preimplantation genetic diagnosis (PGD) for Huntington's disease: the experience of three European centres.

This study provides an overview of 13 years of experience of preimplantation genetic diagnosis (PGD) for Huntington's disease (HD) at three European PGD centres in Brussels, Maastricht and Strasbourg. Information on all 331 PGD intakes for HD, couples' reproductive history, PGD approach, treatment cycles and outcomes between 1995 and 2008 were collected prospectively. Of 331 couples for intake, 68% requested direct testing and 32% exclusion testing (with a preponderance of French couples).

Advances in prenatal screening: the ethical dimension.

Prenatal screening strategies are undergoing rapid changes owing to the introduction of new testing techniques. The overall tendency is towards broadening the scope of prenatal testing through increasingly sensitive ultrasound scans and genome-wide molecular tests. In addition, non-invasive prenatal diagnosis is likely to be introduced in the near future.

Non-invasive prenatal diagnosis for aneuploidy: toward an integral ethical assessment.

The great promise of the pending introduction of non-invasive prenatal diagnosis (NIPD) for trisomy 21 (18 and 13) is that it enables one-step, early and safe testing for these abnormalities. The ethical debate so far has been limited to possible drawbacks of routine access to this type of testing: normalization of testing and abortion and adverse effects on autonomous decision-making. We address the ethical implications of the fact that routine NIPD affects the scope and strategy of current prenatal screening cascades.