Pregnancy outcomes of prenatally diagnosed Turner syndrome: a French multicenter retrospective study including a series of 975 cases.

OBJECTIVES: The objectives of this study were to report pregnancy outcomes after prenatal diagnosis of Turner syndrome (TS) and to compare and assess termination of pregnancy rates during two periods. The intervals selected were before and after 1997 when multidisciplinary centers for prenatal diagnosis (MCPDs) were established in France. METHODS: A database of 975 cases of TS diagnosed between 1980 and 2012 was created from 21 French cytogenetics laboratories. For each case, the karyotype indication, maternal age, year of prenatal testing, sampling procedure, karyotype, associated ultrasound findings, and outcomes were recorded. RESULTS: Karyotypes were mainly performed because of abnormal sonographic findings (84%). Before 1997, there were no changes in the rate of termination (90%) of affected fetuses. After 1997, the rate fell to 80%. This decrease was mainly observed in cases of mosaicism, incidental diagnosis, and in later gestations. US abnormalities were more likely to be associated with a full 45,X karyotype. CONCLUSION: There was an evolution in the way genetic counseling was performed following prenatal diagnosis of Turner syndrome that coincided with the opening of MCPDs in France. This resulted in a decrease in the rate of termination of affected fetuses.

Involvement and alteration of the Sonic Hedgehog pathway is associated with decreased cholesterol level in trisomy 18 and SLO amniocytes.

BACKGROUND: Trisomy 18 and Smith-Lemli-Opitz syndrome are two polymalformative conditions in which a cholesterol defect has been noted. When they occur prenatally, they are associated with a decreased maternal unconjugated estriol (uE(3)) level. Cholesterol plays an essential role in the Sonic Hedgehog pathway, allowing Shh protein maturation leading to its maximal activity. Many malformations in these two syndromes occur in Shh dependent tissues. We thus sought to assess whether a cholesterol defect could affect the Shh pathway and explain some of the observed malformations. MATERIALS AND METHODS: We selected 14 cases of trisomy 18 and 3 cases of SLO in which the maternal uE(3) level was decreased and reported malformations were observed after fetopathological examination. We correlated the number of malformations with maternal uE(3) level. We then carried out cholesterol concentrations in separate culture media consisting of trisomy 18, SLO and control amniocytes. Finally, we analyzed the Shh pathway by testing the gene expression of several Shh components: GLI transcription factors, BMP2, BMP4, TGFß1, COL1A1 and COL1A2. RESULTS AND DISCUSSION: There was an inverse correlation between phenotypic severity and maternal uE(3) levels in SLO and trisomy 18. The cholesterol levels in the amniocyte culture media were correlated with maternal uE3 levels and were significantly lower in T18 and SLO amniocytes, reflecting cholesterol defects. There was an alteration in the Shh pathway since expression of several genes was decreased in T18 and SLO amniocytes. However, these cholesterol defects were not solely responsible for the altered Shh pathway and the malformations observed.

Pregnancy outcomes in 188 French cases of prenatally diagnosed Klinefelter syndrome.

BACKGROUND: Klinefelter syndrome (KS), a common sex chromosome aneuploidy (47,XXY) is diagnosed prenatally with an incidence of 0.15%. The diagnosis is generally incidental, since there are no typical malformations on ultrasound (US). Once detected, genetic counseling is often difficult and the parents' decision to continue or terminate the pregnancy is greatly dependent on the amount and nature of the information provided. We sought to assess the pregnancy outcomes (i.e. continuation versus termination) and the influence of multidisciplinary centers for prenatal diagnosis on parental decisions in cases of KS. METHODS: From 1985 to 2009, 188 prenatal diagnoses of KS were made by 11 participating laboratories in mainland France. In each case, the karyotype indication, parental ages, year of prenatal testing, sampling procedure, karyotype, associated US findings and outcome were recorded. RESULTS AND CONCLUSIONS: The pregnancy termination rate declined markedly over time, from 46.9% before 1997 to 11.6% thereafter, in line with the introduction of new legislation on prenatal diagnosis for medical reasons and, more specifically, the creation of multidisciplinary prenatal diagnosis centers. However, an additional microdeletion in one KS infant who exhibited echogenic bowel on US was unfortunately diagnosed postnatally. This raises the question as to whether array comparative genomic hybridization should be prenatally advised when US abnormalities are detected, in line with advice for fetuses with a normal karyotype.

A novel mutation 3090 G>A of the mitochondrial 16S ribosomal RNA associated with myopathy.

We describe a young woman who presented with a progressive myopathy since the age of 9. Spectrophotometric analysis of the respiratory chain in muscle tissue revealed combined and profound complex I, III, II+III, and IV deficiency ranging from 60% to 95% associated with morphological and histochemical abnormalities of the muscle. An exhaustive screening of mitochondrial transfer and ribosomal RNAs showed a novel G>A substitution at nucleotide position 3090 which was detected only in urine sediment and muscle of the patient and was not found in her mother's blood cells and urine sample. We suggest that this novel de novo mutation in the 16S ribosomal RNA, a nucleotide which is highly conserved in different species, would impair mitochondrial protein synthesis and would cause a severe myopathy.

Hyperechogenic fetal bowel: a large French collaborative study of 682 cases.

Hyperechogenic fetal bowel is detected in 0.1-1.8% of pregnancies during the second or third trimester. This ultrasound sign is associated with cystic fibrosis or other conditions (e.g., chromosomal anomalies, viral infection) but no large-scale prospective studies have been conducted. This 1997-1998 multicenter study in 22 molecular biology laboratories identified 682 cases of hyperechogenic fetal bowel detected by routine ultrasound examination during the second (86%) or third trimester. The fetal bowel was considered hyperechogenic when its echogenicity was broadly similar to, or greater than, that of the surrounding bone. Karyotyping, screening for viral infection, and screening for cystic fibrosis mutations were performed in all cases. Pregnancy outcome and postnatal follow-up were obtained in 656 of the 682 cases (91%). In 447 cases (65.5%), a normal birth was observed. Multiple malformations were observed in 47 cases (6.9%), a significant chromosomal anomaly was noted in 24 (3.5%), cystic fibrosis in 20 (3%), and viral infection in 19 (2.8%). In utero unexplained fetal death occurred in 1.9% of cases, toxemia in 1.2%, IUGR in 4.1%, and premature birth in 6.2%. This study demonstrates that this ultrasound sign is potentially associated with medically significant outcomes. Having established that the bowel is hyperechogenic, recommended investigations should include a detailed scan with Doppler measurements, fetal karyotyping, cystic fibrosis screening, and infectious disease screening. After birth, newborns require pediatric examination because a surgical treatment may be necessary. This should be combined with clear counseling of the parents.

Fifteen new mutations (-195C>T, L-12X, 298-2A>G, T117N, A159T, R229S, 997+2T>A, E274X, A331T, H364R, D389G, 1256delC, R433H, N461I, C472S) in the tissue-nonspecific alkaline phosphatase (TNSALP) gene in patients with hypophosphatasia.

Hypophosphatasia is a rare inherited disorder characterized by defective bone mineralization and deficiency of serum and liver/bone/kidney-type alkaline phosphatase (L/B/K ALP) activity. We report the characterization of tissue-nonspecific alkaline phosphatase (TNSALP) gene mutations in a series of 12 families affected by severe or mild hypophosphatasia. Twenty distinct mutations were found, 5 of which were previously reported. Nine of the 15 new mutations were missense mutations (T117N, A159T, R229S, A331T, H364R, D389G, R433H, N461I, and C472S). The others were 2 nonsense mutations (L-12X and E274X), one single nucleotide deletion (1256delC), 2 mutations affecting splicing (298-2A>G, 997+2T>A), and a mutation in the major transcription start site (-195C>T). Hum Mutat 15:293, 2000.

Maternal serum pregnancy-associated plasma protein A (PAPP-A) but not pregnancy-specific beta1-glycoprotein (SP1) is a useful second-trimester marker for fetal trisomy 18.

The usefulness of early second-trimester serum determinations of pregnancy-associated plasma protein A (PAPP-A) and pregnancy-specific beta1-glycoprotein (SP1) in suspected cases of fetal trisomy 18 was examined in a retrospective, cross-sectional study. Maternal serum PAPP-A and SP1 in 20 cases of fetal trisomy 18 between 15 and 20 weeks of pregnancy, and in 40 controls matched for gestational age and storage time were determined and compared with hCG and free oestriol (uE3). In trisomy 18, the reduction in serum concentration was found to be more pronounced for PAPP-A than for hCG and free oestriol. While none of the 40 control sera had a MoM below 0.2 for either PAPP-A, hCG or uE3, in the trisomy 18 group (20 cases) 17 (85 per cent) of the PAPP-A but only 5 (25 per cent) of the hCG and 4 (20 per cent) of the uE3 results were below the 0.2 MoM threshold. SP1 did not distinguish between controls and trisomy 18. This chromosomal abnormality is too rare a condition to justify maternal serum PAPP-A determination in the second trimester as a routine procedure, but such a test can play a useful role whenever the risk of trisomy 18 is found to be only marginally increased after hCG and uE3 measurements.

The usefulness of hCG and unconjugated oestriol in prenatal diagnosis of trisomy 18.

OBJECTIVE: To evaluate the usefulness of the two maternal serum markers, human chorionic gonadotrophin (hCG) and unconjugated oestriol (uE3), in the prenatal diagnosis of trisomy 18. DESIGN: Retrospective evaluation of uE3 and hCG levels at mid-trimester in cases ot trisomy 18 pregnancies identified from a series of women screened for Down's syndrome. SETTING: From a series of 53,893 women screened in the antenatal centre of University Hospital of Caen (France), 22 cases of trisomy 18 were diagnosed either after amniocentesis for maternal age, elevated risk of Down's syndrome, or fetal abnormalities and/or growth retardation on ultrasound assessment, or after birth. In addition, ll cases of trisomy 18 identified prenatally in two other centres were included. RESULTS: Individual hCG and uE3 levels for pregnancies with trisomy 18 were significantly lower than in unaffected pregnancies: mean hCG was 0.62 multiples of the median (MoM) and median hCG was 0.5 MoM. uE3 was a much more effective marker than hCG. Mean uE3 was 0.40 MoM and median uE3 was 0.37 MoM. It was observed that screening for trisomy 18 based on selection for amniocentesis with cut-off values of 0.55 for hCG and 0.60 for uE3 would lead to a detection rate of 48% for 0.8% false positive rate. Using cut-off values of 0.70 MoM for each one of the two markers would detect 79% of cases of trisomy 18 with 3% false positive rate. CONCLUSIONS: Our results confirm that low hCG and uE3 levels observed in the mid-trimester are predictive of an increased risk for trisomy 18. Since most fetuses with trisomy 18 exhibit morphological abnormalities which should be detected following a careful ultrasonographic examination, biochemical screening could help in the detection of those anatomical defects in selecting for scanning a group of high risk women.

Screening for fetal Down syndrome with maternal serum hCG and oestriol: a prospective study.

We report the preliminary results of a prospective study aimed at evaluating the effectiveness of Down syndrome (DS) screening using second-trimester measurement of maternal serum human chorionic gonadotrophin (hCG) and unconjugated oestriol (uE3) together with maternal age. Reference values for hCG, uE3, and the hCG/uE3 ratio in normal pregnancies were established from more than 3000 normal gestations and found to follow a log-normal statistical distribution. Risk evaluation was made using reference values for affected pregnancies from retrospective studies. Screening of 10,000 women under 38 years resulted in 412 amniocenteses and the prenatal diagnosis of six cases of DS, whereas four cases remained undetected until term. In a parallel study, diagnostic amniocentesis was performed in women over 38 years and in women with a previous affected child, and an evaluation of the risk of fetal DS based on serum hCG and uE3 levels was made in all cases. Fourteen cases of DS were detected. Median values for hCG and uE3 in the 24 affected pregnancies were close to the 90th and tenth centiles of the normal reference values, respectively, and thus are in good agreement with the values reported by others in retrospective studies.

Prenatal diagnosis of a mosaic 46,XY/47,X,i(Xq)Y.

A case of mosaic 46,XY/47,X,i(Xq)Y is diagnosed at 18 gestational weeks in amniotic fluid cells and confirmed at birth in the lymphocytes of the child. The literature on Klinefelter's syndromes with structural chromosome X rearrangements is reviewed. This is the first case reported of a mosaic isochromosome Xq in a boy.

[Balanced translocations with abnormal phenotype (author's transl)]. / Translocations apparemment équilibrées à phénotype anormal.

Four cases of balanced translocations with phenotype abnormalities are reported. Three of them are reciprocal translocation, one is a Robertsonnian translocation. The consequences of the phenomene on genetic counselling and prenatal diagnosis are discussed.