Experts' opinions on the benefit of an incidental prenatal diagnosis of sex chromosomal aneuploidy: a qualitative interview survey.

OBJECTIVE: Incidental findings in prenatal diagnostic testing may or may not have clear prognostic significance for the phenotype. We studied experts' opinions of the benefit and disadvantage of an incidental prenatal diagnosis of a sex chromosomal aneuploidy (SCA). METHODS: We interviewed 16 experts in the field of counseling and treatment of people with SCA and asked 13 clinical geneticists and genetic associates about the clinical relevance of an incidental prenatal diagnosis of SCA. RESULTS: Most of the experts and clinical geneticists (87.5% and 76.9%, respectively) stated that an incidental prenatal diagnosis of SCA was a benefit for the child and the parents. They acknowledged the possibility of parental decisions to terminate pregnancy. Expert options in screening, training, and treatment of health, behavior, and fertility problems increase with an early diagnosis of SCA. CONCLUSION: Most experts favored an incidental prenatal diagnosis of SCA despite the complex counseling issues and their acknowledgment of possible parental decisions to terminate pregnancy. They believed the benefits greatly outweigh the disadvantages.

Incidental prenatal diagnosis of sex chromosome aneuploidies: health, behavior, and fertility.

Objective. To assess the diagnostic relevance of incidental prenatal findings of sex chromosome aneuploidies. Methods. We searched with medical subject headings (MeSHs) and keywords in Medline and the Cochrane Library and systematically screened publications on postnatally diagnosed sex chromosomal aneuploidies from 2006 to 2011 as well as publications on incidentally prenatally diagnosed sex chromosomal aneuploidies from 1980 to 2011. Results. Postnatally diagnosed sex chromosomal aneuploidies demonstrated three clinical relevant domains of abnormality: physical (22-100%), behavior (0-56%), and reproductive health (47-100%), while incidentally prenatally diagnosed sex chromosomal aneuploidies demonstrated, respectively, 0-33%, 0-40%, and 0-36%. Conclusion. In the literature incidental prenatal diagnosis of sex chromosomal aneuploidies is associated with normal to mildly affected phenotypes. This contrasts sharply with those of postnatally diagnosed sex chromosomal aneuploidies and highlights the importance of this ascertainment bias towards the prognostic value of diagnosis of fetal sex chromosomal aneuploidies. This observation should be taken into account, especially when considering excluding the sex chromosomes in invasive prenatal testing using Rapid Aneuploidy Detection.

Intra-individual stability over time of standardized anti-Mullerian hormone in FMR1 premutation carriers.

BACKGROUND: Carriers of a premutation (CGG repeat length 55-200) in the fragile X mental retardation (FMR1) gene are at risk for primary ovarian insufficiency (FXPOI). The anti-Müllerian hormone (AMH) level acts as a useful marker of ovarian follicle reserve and, thus, may serve to predict when this ovarian reserve becomes too low to sustain ovarian function. We investigated the intra-individual variation of AMH levels over time for premutation carriers compared with non-carriers. METHODS: We determined AMH levels in blood samples from 240 women ascertained through fragile X families, of which 127 were premutation carriers and 113 were non-carriers. Linear mixed models were used to assess the effect of age and premutation status on AMH levels and to determine a modeled AMH value. The stability over time of the deviation of observed AMH levels from modeled levels, referred to as standardized AMH values, was assessed through correlation coefficients of 41 longitudinal samples. RESULTS: At all ages, premutation carriers exhibited lower AMH levels. For all women, AMH was found to decrease by 10% per year. The added effect of having a premutation decreased AMH levels by 54%. The deviation of an individual's AMH level from the modeled value showed a reasonable intra-individual correlation. The Pearson correlation coefficient of two samples taken at different ages was 0.36 (P = 0.05) for non-carriers and 0.69 (P = 0.01) for carriers. CONCLUSIONS: We developed a unique standardized AMH value, taking FMR1 premutation status and the subject's age into account, which appears to be stable over time and may serve as a predictor for FXPOI after further longitudinal assessment.

Parents' perspectives on the unforeseen finding of a fetal sex chromosomal aneuploidy.

OBJECTIVE: To investigate the parental perspectives of being confronted with an unforeseen fetal sex chromosomal aneuploidy (SCA), in light of the fact that this accidental finding is avoidable by rapid aneuploidy detection (RAD). METHODS: Exploratory qualitative interview study. We conducted 16 semi-structured interviews with parents who decided to continue pregnancy after the unforeseen finding of a fetal SCA. RESULTS: The communication of the unforeseen finding of SCA; the informed decision-making process concerning the pregnancy follow-up and the child and its future were the extracted themes. Parents were not prepared to accidental findings in routine prenatal diagnostics. All started an unguided search on the Internet. It is not at all clear whether parents have preference for an RAD test with X and Y probes Parents were satisfied with the post-test professional information they received to make an informed decision, whereas after birth questions still remained to be answered. CONCLUSION: Parents' perspectives may serve as major contributors to research on the question whether or not the X and Y probes should be standard included for purposes of RAD. The fact that RAD has the possibility to avoid accidental findings of SCAs, brings up the question whether any benefits outweigh the potential harms.

Identification of clinically significant, submicroscopic chromosome alterations and UPD in fetuses with ultrasound anomalies using genome-wide 250k SNP array analysis.

BACKGROUND: The implementation of microarray analysis in prenatal diagnostics is a topic of discussion, as rare copy number variants with unknown/uncertain clinical consequences are likely to be found. The application of targeted microarrays limits such findings, but the potential disadvantage is that relevant, so far unknown, aberrations might be overlooked. Therefore, we explore the possibilities for the prenatal application of the genome-wide 250k single nucleotide polymorphism array platform. METHODS: Affymetrix 250k NspI single nucleotide polymorphism array analysis (Affymetrix, Inc., Santa Clara, California, USA) was performed on DNA from 38 prenatally karyotyped fetuses with ultrasound anomalies. Analyses were performed after termination of pregnancy, intrauterine fetal death or birth on DNA isolated from fetal or neonatal material. RESULTS: Aberrations were detected in 17 of 38 fetuses, 6 of whom with a previously identified chromosomal abnormality and 11 with previously normal or balanced karyotypes. Of the latter, the detected aberration occurred de novo and was considered of clinical relevance in five cases (16%), inherited from a healthy parent in four cases (12%), and de novo yet with unclear clinical relevance in two cases (6%). The clinically relevant abnormalities either were novel copy number variants (n=3) or concerned a uniparental disomy (n=2). CONCLUSION: In at least 16% of fetuses with ultrasound anomalies and a normal or balanced karyotype, causal (submicroscopic) aberrations were detected, illustrating the importance of the (careful) implementation of microarray analysis in prenatal diagnosis. The fact that the identified, clinically relevant, aberrations would have gone undetected with most targeted approaches underscores the added value of a genome-wide approach.

A small (sSMC) chromosome 22 due to a maternal translocation between chromosomes 8 and 22: a case report.

We report on a boy with partial trisomies for chromosomes 8 and 22 caused by the presence of a small supernumerary marker chromosome (sSMC), a der(22)t(8;22)(p22;q11.21), inherited from a t(8;22)(p22;q11.21) translocation carrier mother. He has mild mental retardation, unability to speak distinct words and several minor anomalies i.e. high forehead and hairline, telecanthus, upslanting palpebral fissures, depressed nasal bridge, nail hypoplasia, toe position anomaly and 5th finger clinodactyly. He has two maternal uncles and one maternal aunt with mental retardation. G-banding technique showed 47,XY,+mar whilst his mother's karyotype showed a balanced reciprocal translocation between the chromosomes 8 and 22. Fluorescence In Situ Hybridization (FISH) technique with probes for centromere 22 and 8pter were used to detect the origin of marker chromosome and confirmed the marker chromosome in the proband showing to be extra chromosomal material originated from chromosome 8 and 22. Additional genome wide microarray analysis, using the Affymetrix Nspl 250K SNP array platform was performed to further characterize the marker chromosome and resulted in a der(22)t(8;22)(p22;q11.21). Furthermore, cytogenetic analysis of three affected family members showed the same unbalanced translocation, due to 3:1 meiotic segregation. This indicated the viability of this unbalanced pattern and combined with the recurrent miscarriages by the proband's mother, the mechanism of transmitting extrachromosomal material is probably not a random process. Since, there is no similar translocation (8p;22q) reported and the chromosomal translocation largely exists of additional 8p22-8pter we compare the clinical outcomes with reported cases of 8p22-8pter triplication, although there is a part of genetic material derived from chromosome 22 present. This unique familial chromosome translocation case from Indonesia will give insight in the underlying mechanism of this recurrent chromosomal abnormality and clinical features of the patients will be compared to previously published cases.

[Alpha-foetoprotein assessment in amniotic fluid for the detection of neural tube defects: limited added value beyond week 20 ultrasound; retrospective study]. / Alfafoetoproteïnebepaling in vruchtwater voor de detectie van neuralebuisdefecten: beperkte meerwaarde boven de 20-wekenecho; retrospectiefonderzoek.

OBJECTIVE: To evaluate the diagnostic additional value of routine alpha-foetoprotein (AFP) assessment in amniotic fluid for the detection of neural tube defects (NTDs), compared with week 20 ultrasonographic examination. DESIGN: Retrospective. METHOD: We retrospectively determined AFP concentrations in amniotic fluid obtained from 7981 women who had undergone amniocentesis for karyotyping and AFP assessment. An AFP concentration greater than 2.5 times the median was considered abnormal. Women were categorised into 4 groups based on the indication for invasive prenatal diagnostic assessment: advanced maternal age (group I; n = 6179), increased risk of foetal NTDs (group II; n = 258), ultrasonographically confirmed foetal NTDs (group III; n = 55) or other indications (group IV; n = 1489). RESULTS: In group I, 18 of 6179 samples had increased AFP levels (0.3%), 2 of which were associated with NTDs. In group II, 2 of 258 samples had increased AFP levels (0.8%); both were associated with NTDs. Increased AFP levels were found in 44 of 55 samples from group III (80%), and 223 of 1489 samples from group IV (15.0%). CONCLUSION: Routine assessment of AFP in amniotic fluid based on advanced maternal age provides little additional value in the detection of NTDs beyond that of week 20 ultrasound.

Female carriers of fragile X premutations have no increased risk for additional diseases other than premature ovarian failure.

Carriers of fragile X premutations were previously considered phenotypically normal but are now known to be at risk for premature ovarian failure (POF). This prompted us to investigate whether premutation carriers (PC) have an increased risk for other diseases. We approached 306 women out of 84 fra(X) families of whom 264 (86.3%) participated in this study. A medical history was taken of these women. Whenever possible, the anamnestic data were verified with medical records. We first evaluated the occurrence of diseases that are commonly associated with menopause in PC and compared this to that in women with either a normal FMR-1 gene or a full mutation. We found no statistically significant differences in the occurrence of diseases known to be associated with menopause, such as cardiovascular diseases and osteoporosis. However, lower bone mineral density was observed only in PC. Subsequently, we compared the occurrence of other medical problems between the two groups by estimating relative risks. PC did not demonstrate other diseases more commonly compared to non-PC from the same families. These findings are important for the counseling of PC. Carriership of the premutation may affect the ovaries, but does not substantially increase the risk for additional medical problems. Once a PC does experience POF, she is at risk for early estrogen deprivation, which may lead to a premature decrease in bone density, when not treated.

[Perinatal asphyxia as incorrect explanation for mental retardation]. / 'Perinatale asfyxie' als onterechte verklaring voor mentale retardatie.

Three women, aged 21, 34 and 32 and with a family history of mental retardation said to be caused by perinatal asphyxia, each gave birth to a child with mental retardation. A chromosomal translocation, fragile X syndrome, and myotonic dystrophy could be diagnosed, respectively. In retrospect, the diagnosis of perinatal asphyxia in the family history had been too readily accepted. In reality the mental retardation was caused by a genetic disorder. Physicians are used to making a diagnosis, and when a diagnosis is not (yet) possible, they try to establish a working diagnosis or differential diagnosis. Too often such a working diagnosis becomes, through time, a definite diagnosis.

Increased serum FSH in female fragile X premutation carriers with either regular menstrual cycles or on oral contraceptives.

Fragile X premutations are known to be a risk factor for diminished ovarian function at a relatively young age. We studied endocrine profiles of female fragile X family members (n = 79) at risk of premature ovarian failure (POF). Of these 79 women aged <40 years, 45 had menstrual cycles, and 34 were using oral contraceptives. Of the women with menstrual cycles, the premutation carriers had higher serum FSH concentrations than women who were not carrying the premutation. Even premutation carriers with regular cycles showed increased serum FSH concentrations. Moreover, premutation carriers using oral contraceptives also demonstrated increased serum FSH concentrations. Irrespective of whether oral contraceptives were used, a serum FSH concentration of > or =15 IU/l was more common in the premutation carriers than in the other women. One premutation carrier using oral contraceptives had a serum FSH concentration of >40 IU/l, the threshold that defines POF. We confirmed that premutation carriers with menstrual cycles demonstrate premature ovarian dysfunction. However, we also found endocrine signs of unrecognized ovarian dysfunction in premutation carriers using oral contraceptives, despite endocrine alterations by oral contraceptives. Premutation carriers may have a poorer prognosis for future pregnancy, either achieved spontaneously or by assisted reproductive technology. We recommend that premutation carriers should be counselled not to wait too long if they wish to start a family.

Imprinting effect in premature ovarian failure confined to paternally inherited fragile X premutations.

Fragile X premutations are considered to be a risk factor for premature ovarian failure (POF), which is usually defined as menopause at age <40 years. Since premutations may be inherited from either the mother or the father, we evaluated the influence of the inheritance pattern on the duration of reproductive life in female carriers. The occurrence of POF and age at menopause in women with a paternally inherited fragile X premutation (PIP) were compared to those in women with a maternally inherited fragile X premutation (MIP). We identified 148 women in whom the parental origin of the premutation could be determined. In 109 of these women we were able to establish whether POF had occurred: 82 women had a PIP, and 27 had a MIP. Twenty-three of the women (28%) with a PIP had POF, versus only 1 (3.7%) with a MIP (two -tailed Fisher's exact test; P=. 007). Kaplan-Meier analysis of all 148 premutations showed that the age at menopause was significantly lower in the women with a PIP than in the woman with a MIP (Breslow test in Kaplan-Meier analysis; P=.003). Our data strongly suggest that, when POF occurs in fragile X premutation carriers, a considerable proportion of the premutations are inherited paternally (parent-of-origin effect). We hypothesize that this may be owing to a paternal genomic imprinting effect.

Heterozygous germline mutations in the p53 homolog p63 are the cause of EEC syndrome.

EEC syndrome is an autosomal dominant disorder characterized by ectrodactyly, ectodermal dysplasia, and facial clefts. We have mapped the genetic defect in several EEC syndrome families to a region of chromosome 3q27 previously implicated in the EEC-like disorder, limb mammary syndrome (LMS). Analysis of the p63 gene, a homolog of p53 located in the critical LMS/EEC interval, revealed heterozygous mutations in nine unrelated EEC families. Eight mutations result in amino acid substitutions that are predicted to abolish the DNA binding capacity of p63. The ninth is a frameshift mutation that affects the p63alpha, but not p63beta and p63gamma isotypes. Transactivation studies with these mutant p63 isotypes provide a molecular explanation for the dominant character of p63 mutations in EEC syndrome.

Familial idiopathic premature ovarian failure: an overrated and underestimated genetic disease?

The incidence of familial cases of premature ovarian failure varies from 4 to 31%. Recall bias may explain part of the variance. Thorough evaluation of alleged affected relatives showed a lower incidence than the original family history suggested. In the present study the incidence of familial cases was 12.7%. Pedigree studies on affected families showed a mode of inheritance suggestive of autosomal dominant sex-limited transmission or X-linked inheritance with incomplete penetrance. An adequate family history can distinguish between familial or sporadic premature ovarian failure. The risk of female relatives developing premature ovarian failure may be as high as 100% in familial premature ovarian failure, or as low as 1% in sporadic cases.

Four families (MRX43, MRX44, MRX45, MRX52) with nonspecific X-linked mental retardation: clinical and psychometric data and results of linkage analysis.

Four families are described in which mental retardation segregates in an X-linked fashion. Mental retardation was the only consistent clinical finding in all affected males. The degree of retardation varied from mild to profound both between and within families. Linkage analysis localized the genetic defect of MRX43 to Xp22. 31-p21.2, MRX44 to Xp11.3-p11.21, MRX45 to Xp11.3-p11.21, and MRX52 to Xp11.21-q21.33 with LOD scores of >2 at straight theta = 0.0 in all four families.

X-linked mental retardation: evidence for a recent mutation in a five-generation family (MRX65) linked to the pericentromeric region.

We report linkage analysis in a new family with nonspecific X-linked mental retardation, using 27 polymorphic markers covering the entire X-chromosome. We could assign the underlying disease gene, denoted MRX65, to the pericentromeric region, with flanking markers DXS573 in Xp11.3 and DXS990 in Xq21.33. A maximum LOD score of 3.64 was found at markers ALAS2 (Xp11.22) and DXS453 (Xq12) at straight theta = 0. Twenty-five of the 58 reported MRX families are linked to a region that is partially overlapping with the region reported here. Extension of the pedigree showed a number of unaffected distant relatives with haplotypes corresponding to the disease locus. Apparently, a new mutation in a female is causative for the disease in the family reported here. Furthermore, we show the importance of combining clinical, cytogenetic, and molecular studies since one of the family members, expected to be affected by the same genetic defect, has a 48,XXXY karyotype.

Psychometric assessment of families with X-linked mental retardation.

As part of an integrated approach to DNA-linkage analysis in X-linked mental retardation (XLMR), 29 members of five families suspected of having XLMR underwent psychometric assessment. Mental retardation was confirmed in all participants. The range of mental retardation varied from mild to profound within and between families. In addition, these preliminary results indicated family-specific cognitive profiles in MRX45 and MRX46. The fact that two non-overlapping loci were involved provides strong evidence that specific cognitive profiles are linked to specific loci (genes) in mental retardation. We therefore recommend the application of standardised psychometric tests for the assessment of XLMR.

Menstrual disorders and endocrine profiles in fragile X carriers prior to 40 years of age: a pilot study.

This prospective study reports serum hormone measurements associated with menopause in fragile X carriers (n = 9, age between 31-40 years). These results demonstrate the occurrence of premature ovarian failure.

Limb mammary syndrome: a new genetic disorder with mammary hypoplasia, ectrodactyly, and other Hand/Foot anomalies maps to human chromosome 3q27.

We report on a large Dutch family with a syndrome characterized by severe hand and/or foot anomalies, and hypoplasia/aplasia of the mammary gland and nipple. Less frequent findings include lacrimal-duct atresia, nail dysplasia, hypohydrosis, hypodontia, and cleft palate with or without bifid uvula. This combination of symptoms has not been reported previously, although there is overlap with the ulnar mammary syndrome (UMS) and with ectrodactyly, ectodermal dysplasia, and clefting syndrome. Allelism with UMS and other related syndromes was excluded by linkage studies with markers from the relevant chromosomal regions. A genomewide screening with polymorphic markers allowed the localization of the genetic defect to the subtelomeric region of chromosome 3q. Haplotype analysis reduced the critical region to a 3-cM interval of chromosome 3q27. This chromosomal segment has not been implicated previously in disorders with defective development of limbs and/or mammary tissue. Therefore, we propose to call this apparently new disorder "limb mammary syndrome" (LMS). The SOX2 gene at 3q27 might be considered an excellent candidate gene for LMS because the corresponding protein stimulates expression of FGF4, an important signaling molecule during limb outgrowth and development. However, no mutations were found in the SOX2 open reading frame, thus excluding its involvement in LMS.

Localisation of a gene for non-specific X linked mental retardation (MRX46) to Xq25-q26.

We report linkage data on a new large family with non-specific X linked mental retardation (MRX), using 24 polymorphic markers covering the entire X chromosome. We could assign the underlying disease gene, denoted MRX46, to the Xq25-q26 region. MRX46 is tightly linked to the markers DXS8072, HPRT, and DXS294 with a maximum lod score of 5.12 at theta=0. Recombination events were observed with DXS425 in Xq25 and DXS984 at the Xq26-Xq27 boundary, which localises MRX46 to a 20.9 cM (12 Mb) interval. Several X linked mental retardation syndromes have been mapped to the same region of the X chromosome. In addition, the localisation of two MRX genes, MRX27 and MRX35, partially overlaps with the linkage interval obtained for MRX46. Although an extension of the linkage analysis for MRX35 showed only a minimal overlap with MRX46, it cannot be excluded that the same gene is involved in several of these MRX disorders. On the other hand, given the considerable genetic heterogeneity in MRX, one should be extremely cautious in using interfamilial linkage data to narrow down the localisation of MRX genes. Therefore, unless the underlying gene(s) is characterised by the analysis of candidate genes, MRX46 can be considered a new independent MRX locus.