Fetal phenotype of Rubinstein-Taybi syndrome caused by CREBBP mutations.

Rubinstein-Taybi syndrome (RSTS; OMIM 180849) is an autosomal dominant developmental disorder characterized by facial dysmorphism, broad thumbs and halluces associated with intellectual disability. RSTS is caused by alterations in CREBBP (about 60%) and EP300 genes (8%). RSTS is often diagnosed at birth or during early childhood but generally not suspected during antenatal period. We report nine cases of well-documented fetal RSTS. Two cases were examined after death in utero at 18 and 35 weeks of gestation and seven cases after identification of ultrasound abnormalities and termination of pregnancy. On prenatal sonography, a large gallbladder was detected in two cases, and brain malformations were noted in four cases, especially cerebellar hypoplasia. However, the diagnosis of RSTS has not been suggested during pregnancy. Fetal autopsy showed that all fetuses had large thumbs and/or suggestive facial dysmorphism. A CREBBP gene anomaly was identified in all cases. Alterations were similar to those found in typical RSTS children. This report will contribute to a better knowledge of the fetal phenotype to consider the hypothesis of RSTS during pregnancy. Genotyping allows reassuring genetic counseling.

Early-onset obesity and paternal 2pter deletion encompassing the ACP1, TMEM18, and MYT1L genes.

Obesity is a common but highly, clinically, and genetically heterogeneous disease. Deletion of the terminal region of the short arm of chromosome 2 is rare and has been reported in about 13 patients in the literature often associated with a Prader-Willi-like phenotype. We report on five unrelated patients with 2p25 deletion of paternal origin presenting with early-onset obesity, hyperphagia, intellectual deficiency, and behavioural difficulties. Among these patients, three had de novo pure 2pter deletions, one presented with a paternal derivative der(2)t(2;15)(p25.3;q26) with deletion in the 2pter region and the last patient presented with an interstitial 2p25 deletion. The size of the deletions was characterized by SNP array or array-CGH and was confirmed by fluorescence in situ hybridization (FISH) studies. Four patients shared a 2p25.3 deletion with a minimal critical region estimated at 1.97 Mb and encompassing seven genes, namely SH3HYL1, ACP1, TMEMI8, SNTG2, TPO, PXDN, and MYT1L genes. The fifth patient had a smaller interstitial deletion encompassing the TPO, PXDN, and MYT1L genes. Paternal origin of the deletion was determined by genotyping using microsatellite markers. Analysis of the genes encompassed in the deleted region led us to speculate that the ACP1, TMEM18, and/or MYT1L genes might be involved in early-onset obesity. In addition, intellectual deficiency and behavioural troubles can be explained by the heterozygous loss of the SNTG2 and MYT1L genes. Finally, we discuss the parent-of-origin of the deletion.

The 2q37-deletion syndrome: an update of the clinical spectrum including overweight, brachydactyly and behavioural features in 14 new patients.

The 2q37 locus is one of the most commonly deleted subtelomeric regions. Such a deletion has been identified in >100 patients by telomeric fluorescence in situ hybridization (FISH) analysis and, less frequently, by array-based comparative genomic hybridization (array-CGH). A recognizable '2q37-deletion syndrome' or Albright's hereditary osteodystrophy-like syndrome has been previously described. To better map the deletion and further refine this deletional syndrome, we formed a collaboration with the Association of French Language Cytogeneticists to collect 14 new intellectually deficient patients with a distal or interstitial 2q37 deletion characterized by FISH and array-CGH. Patients exhibited facial dysmorphism (13/14) and brachydactyly (10/14), associated with behavioural problems, autism or autism spectrum disorders of varying severity and overweight or obesity. The deletions in these 14 new patients measured from 2.6 to 8.8 Mb. Although the major role of HDAC4 has been demonstrated, the phenotypic involvement of several other genes in the deleted regions is unknown. We further refined the genotype-phenotype correlation for the 2q37 deletion. To do this, we examined the smallest overlapping deleted region for candidate genes for skeletal malformations (facial dysmorphism and brachydactyly), overweight, behavioural problems and seizures, using clinical data, a review of the literature, and the Manteia database. Among the candidate genes identified, we focus on the roles of PRLH, PER2, TWIST2, CAPN10, KIF1A, FARP2, D2HGDH and PDCD1.

A homozygous balanced reciprocal translocation suggests LINC00237 as a candidate gene for MOMO (macrosomia, obesity, macrocephaly, and ocular abnormalities) syndrome.

Macrosomia, obesity, macrocephaly, and ocular abnormalities syndrome (MOMO syndrome) has been reported in only four patients to date. In these sporadic cases, no chromosomal or molecular abnormality has been identified thus far. Here, we report on the clinical, cytogenetic, and molecular findings in a child of healthy consanguineous parents suffering from MOMO syndrome. Conventional karyotyping revealed an inherited homozygous balanced reciprocal translocation (16;20)(q21;p11.2). Uniparental disomy testing showed bi-parental inheritance for both derivative chromosomes 16 and 20. The patient's oligonucleotide array-comparative genomic hybridization profile revealed no abnormality. From the homozygous balanced reciprocal translocation (16;20)(q21;p11.2), a positional cloning strategy, designed to narrow 16q21 and 20p11.2 breakpoints, revealed the disruption of a novel gene located at 20p11.23. This gene is now named LINC00237, according to the HUGO (Human Genome Organization) nomenclature. The gene apparently leads to the production of a non-coding RNA. We established that LINC00237 was expressed in lymphocytes of control individuals while normal transcripts were absent in lymphocytes of our MOMO patient. LINC00237 was not ubiquitously expressed in control tissues, but it was notably highly expressed in the brain. Our results suggested autosomal recessive inheritance of MOMO syndrome. LINC00237 could play a role in the pathogenesis of this syndrome and could provide new insights into hyperphagia-related obesity and intellectual disability.

Proportion of parents agreeing to delay fetal karyotyping until the third trimester of pregnancy in cases with an indication.

OBJECTIVE: To assess the extent to which couples who could benefit from fetal karyotyping during the first or second trimester would agree to delay the examination until the third trimester. METHODS: In this prospective monocentric study, the same physician suggested to some couples to delay fetal karyotyping until the third trimester. RESULTS: 458 couples participated in this study. 230 couples (230/458 = 50.2%) refused to delay the examination until the third trimester of pregnancy (group 1). For these patients, four chromosomal abnormalities led to the termination of pregnancy. Fifty-six couples (56/458 = 12.2%) who initially agreed to delay the fetal karyotyping later changed their minds (group 2). 104 couples (104/458 = 22.7%) agreed to delay the examination (group 3). For these patients, one trisomy 21 was diagnosed and led to the subsequent termination of the pregnancy at 33 weeks of amenorrhea. Sixty-eight couples (68/458 = 14.8%) refused any form of invasive prenatal diagnosis (group 4). There was no difference in the rate of preterm premature rupture of membranes, pregnancy term, premature birth rate and birth weight between the four groups. CONCLUSIONS: Our study reports that about a quarter of couples did indeed agree to delay fetal karyotype assessment until the third trimester of pregnancy.

Identification of a complex 17q rearrangement in a metanephric stromal tumor.

Metanephric stromal tumor is a rare benign entity belonging to the group of metanephric renal tumors in children. Although metanephric stromal tumors can be cured by simple nephrectomy, differential diagnosis based on histopathologic criteria with other pediatric renal tumors requiring aggressive chemotherapy can be difficult. To our knowledge, cytogenetic characterization of metanephric stromal tumor has never been reported. We describe conventional ("R-bands" karyotyping) and molecular [fluorescence in situ hybridization (FISH), multicolor FISH, oligo array-comparative genomic hybridization] cytogenetic examinations of a metanephric stromal tumor in a 3-year-old boy. Cytogenetic analysis revealed a complex homogeneous gain between bands 17q22 and 17q25.3, resulting in partial triplication of the segment between bands 17q22 and 17q24.3, and duplication of the segment between bands 17q24.3 and 17q25.3. Cytogenetic confirmatory studies in metanephric stromal tumors are currently needed to assess 17q22q25.3 gain as a recurring cytogenetic abnormality of metanephric stromal tumors.

Rheumatologic and neurological events in an elderly patient with tricho-rhino-phalangeal syndrome type I.

Sparse scalp hair, a peculiar shape of the nose, and cone-shaped epiphyses of the phalanges are the hallmarks of the tricho-rhino-phalangeal syndromes (TRPS). Short stature, hip dysplasia, and malformations of inner organs including mitral valve prolpase have also often been described for these conditions. Here, we described a 64-year-old woman with molecularly proved TRPS I and several atypical late-onset rheumatologic and neurological symptoms.

An unusual chromosome 22q11 deletion associated with an apparent complementary ring chromosome in a phenotypically normal woman.

We report an unusual chromosome 22q11 deletion associated with an apparent complementary ring chromosome in a phenotypically normal woman with a family medical history of 22q11 deletion. Using peripheral blood samples, conventional karyotyping, Fluorescence In Situ Hybridization (FISH) analysis on metaphase spreads and oligo array-based comparative genomic hybridization (oligo array-CGH) were performed. After conventional cytogenetic examination, the chromosome formula was as follows: 47,XX,+r(?)[16]/46,XX[6]. The FISH analysis revealed that this patient had a rearranged chromosome 22 with decreased centromeric fluorescence intensity and deletion of the 22q11.2 locus. She also had a supernumerary ring chromosome composed of an alpha-satellite centromere of 22 origin and 22q11.2 locus. The oligo array-CGH profile showed a deletion of approximately 4.18 Mb on chromosome 22 with a log 2 intensity ratio mean deviation of the deleted region of about -0.29. The 22q11 deletion associated with a complementary ring chromosome described in our patient could be consistent with a centromere misdivision mechanism, with one chromosomal break occurring in the alpha-satellite array and a second one in the 22q11 locus, a mechanism which has recently been referred to as the McClintock mechanism.

Characterization of a de novo balanced translocation t(9;18)(p23;q12.2) in a patient with oculoauriculovertebral spectrum.

We report a patient presenting with oculoauriculovertebral spectrum and a de novo balanced reciprocal translocation t(9;18)(p23;q12.2). Physical mapping of the translocation breakpoints by fluorescent in situ hybridization showed that the breakpoints are located in two regions encompassing gene deserts. An additional paternally inherited duplication in 18p11.23p11.31 was identified by array-CGH. We discuss the possible involvement of these chromosomal abnormalities in OAVS.

Genotype-phenotype correlations in Down syndrome identified by array CGH in 30 cases of partial trisomy and partial monosomy chromosome 21.

Down syndrome (DS) is one of the most frequent congenital birth defects, and the most common genetic cause of mental retardation. In most cases, DS results from the presence of an extra copy of chromosome 21. DS has a complex phenotype, and a major goal of DS research is to identify genotype-phenotype correlations. Cases of partial trisomy 21 and other HSA21 rearrangements associated with DS features could identify genomic regions associated with specific phenotypes. We have developed a BAC array spanning HSA21q and used array comparative genome hybridization (aCGH) to enable high-resolution mapping of pathogenic partial aneuploidies and unbalanced translocations involving HSA21. We report the identification and mapping of 30 pathogenic chromosomal aberrations of HSA21 consisting of 19 partial trisomies and 11 partial monosomies for different segments of HSA21. The breakpoints have been mapped to within approximately 85 kb. The majority of the breakpoints (26 of 30) for the partial aneuploidies map within a 10-Mb region. Our data argue against a single DS critical region. We identify susceptibility regions for 25 phenotypes for DS and 27 regions for monosomy 21. However, most of these regions are still broad, and more cases are needed to narrow down the phenotypic maps to a reasonable number of candidate genomic elements per phenotype.

Molecular cytogenetic characterization of terminal 14q32 deletions in two children with an abnormal phenotype and corpus callosum hypoplasia.

Among previously reported cases of 14q terminal deletions, only 11 have dealt with pure terminal deletion of 14q (14q3-14qter) and the break points were mapped by fluorescent in situ hybridisation (FISH) or genotyping in only four of them. Thanks to a collaborative study on behalf of the 'Association des Cytogeneticiens de langue Française'(ACLF), we report two patients with terminal deletion of the long arm of chromosome 14, del(14)(q32.2) and del(14)(q32.32), diagnosed by subtelomere screening. In the two cases, a thick nuchal skinfold was detected by early ultrasound with normal prenatal karyotype. Their postnatal phenotype included large forehead, narrow palpebral fissures, epicanthic folds, upturned tip of the nose, narrow mouth and thin upper lip, microretrognathia, prominent earlobes, hypotonia, delayed psychomotor development and hypoplastic corpus callosum. By physical mapping using FISH, the size of the deletions was measured for patients 1 and 2: 6.55+/-1.05 and 4.67+/-0.10 Mb, respectively. The paternal origin of the deleted chromosome 14 was established by genotyping of microsatellites for patient 1 and the phenotype of terminal del(14)(q32) was compared to maternal uniparental disomy 14.

Effective gene therapy of mice with congenital erythropoietic porphyria is facilitated by a survival advantage of corrected erythroid cells.

Achieving long-term expression of a therapeutic gene in a given hematopoietic lineage remains an important goal of gene therapy. Congenital erythropoietic porphyria (CEP) is a severe autosomal-recessive disorder characterized by a deficiency in uroporphyrinogen III synthase (UROS), the fourth enzyme of the heme biosynthetic pathway. We used a recently obtained murine model to check the feasibility of gene therapy in this disease. Lentivirus-mediated transfer of the human UROS cDNA into hematopoietic stem cells (HSCs) from Uros(mut248) mice resulted in a complete and long-term enzymatic, metabolic, and phenotypic correction of the disease, favored by a survival advantage of corrected red blood cells. These results demonstrate that the cure of this mouse model of CEP at a moderate transduction level supports the proof of concept of a gene therapy in this disease by transplantation of genetically modified hematopoietic stem cells.

A 580 kb microdeletion in 17q21.32 associated with mental retardation, microcephaly, cleft palate, and cardiac malformation.

We report on a young boy carrying a de novo 580 kb deletion in the 17q21.32 chromosomal band detected by array-CGH. He had multiple malformations including cardiac abnormalities, cleft palate, mental retardation, microcephaly, pronounced metopic suture and other minor facial dysmorphic features. This is the first case reported in the literature with such a small deletion in 17q21.32. This region includes 15 genes.

Combination of WAGR and Potocki-Shaffer contiguous deletion syndromes in a patient with an 11p11.2-p14 deletion.

Aniridia, Wilms tumor, genitourinary abnormalities, growth and mental retardation are the cardinal features of the WAGR 11p13 deletion syndrome. The Potocki-Schaffer syndrome or proximal 11p deletion syndrome (previously DEFECT11 syndrome) is a contiguous gene syndrome associated with deletions in 11p11.2, principal features of which are multiple exostoses and enlarged parietal foramina. Mental handicap, facial dysmorphism and craniosynostosis may also be associated. We report a patient with combined WAGR and Potocki-Shaffer syndromes, and obesity. She presented with aniridia, cataract, nystagmus, corneal ulcers and bilateral congenital ptosis. A left nephroblastoma was detected at 15 months. Other features included moderate developmental delay, growth deficiency, facial dysmorphism, multiple exostoses and cranial lacunae. High-resolution and molecular cytogenetics confirmed a del(11)(p11.2p14.1) deletion with a proximal breakpoint between the cosmid DO8153 and the BAC RP11-104M24 to a distal breakpoint between cosmids CO8160 (D11S151) and F1238 (D11S1446). The deletion therefore includes EXT2, ALX4, WT1 and PAX6. This case appears to be the second patient reported with this combined deletion syndrome and confirms the association of obesity in the WAGR spectrum, a feature previously reported in four cases, and for which the acronym WAGRO has been suggested. Molecular and follow-up data on the original WAGRO case are briefly presented.

Neoplastic cells do not carry bcl2-JH rearrangements detected in a subset of primary cutaneous follicle center B-cell lymphomas.

Whether primary cutaneous follicular lymphoma (PCFL) may or not represent a cutaneous equivalent to nodal follicular lymphoma (FL) is not determined. We have therefore investigated a series of PCFL to determine if tumoral cells carry or not the t(14;18)(q32;q21) translocation, a cytogenetic hallmark of nodal FL. Thirty cases of PFCL were selected according to the criteria of both the European Organisation for Research and Treatment of Cancer and the World Health Organization with 21 cases classified as grade 1 or 2 and 9 cases as grade 3. First, cutaneous tumors were studied by PCR for the amplification of bcl-2/JH rearrangements and by interphase fluorescence in situ hybridization using a dual color probe spanning t(14;18) breakpoints. Second, we tried to determine the origin of bcl2-JH-positive cells by a parallel bcl2-JH and immunoglobulin heavy chain gene amplification of blood mononuclear cells DNA and of DNA extracted from single microdissected B cells. Bcl2-JH rearrangements were amplified by PCR in skin of 9 of 30 (30%) patients with a similar-sized bcl2-JH rearrangement detected in the blood of 7 of these 9 cases. No t(14;18) breakpoint was detected by interphase fluorescence in situ hybridization analysis of 11 bcl2-JH-negative and 5 bcl2-JH-positive PCFL in contrast with its detection in the secondary cutaneous FL and in the nodal FL cases. Single-cell/multigene analysis showed that no single monoclonal B cells of PCFL carried the bcl2-JH rearrangement. Bystander or nontumoral t(14;18)+ B cells emigrating from blood may account for the detection of bcl2-JH rearrangements within PCFL material. Our study also underlines the diagnostic value of interphase fluorescence in situ hybridization to discriminate between t(14;18)-negative PCFL and extracutaneous FL involving the skin.

Prenatal diagnosis and management of sex chromosome aneuploidy: a report on 98 cases.

OBJECTIVES: To analyse the management of pregnancy after prenatal diagnosis of sex chromosome aneuploidy (SCA) and the factors influencing genetic counselling and parental decision. METHODS: Between 1991 and 2001, 73 non-mosaic fetal SCA were diagnosed in our centre and 25 were referred to us from outside institutions. The same geneticist carried out genetic counselling. The outcome of pregnancies and the termination trend over time were determined according to the type of SCA. Clinical parental data were analysed in order to assess whether they influenced genetic counselling. RESULTS: 45,X was diagnosed in 41 fetuses. The main indication for karyotyping was abnormal ultrasound (83%). The termination rate was 93%. Sex chromosome polysomies (SCP) including 47,XXY, 47,XXX, and 47,XYY were diagnosed in 31, 16, and 10 fetuses respectively. The main indication for karyotyping was advanced maternal age (60%). The termination rate was 32, 25, and 20% respectively. The difference between the termination rate for local cases (25%) and referred cases (33%) was not significant. The termination rate for pregnancies with SCP was 38% in 1991 to 1994, 34% in 1995 to 1998, and 12% in 1999 to 2001. The parents' characteristics did not influence the outcome of pregnancy. CONCLUSIONS: The relatively low termination rate (28%) in pregnancies where the fetus was affected by SCP and the decreasing termination trend over time in our centre suggest an improved knowledge of the pathological conditions associated with SCP, influencing genetic counselling.

Analysis of CBP (CREBBP) gene deletions in Rubinstein-Taybi syndrome patients using real-time quantitative PCR.

Rubinstein-Taybi syndrome (RTS) is a well-defined syndrome characterized by facial abnormalities, broad thumbs, broad big toes, and growth and mental retardation as the main clinical features. RTS was shown to be associated with disruption of the CREB-binding protein gene CBP (CREBBP), either by gross chromosomal rearrangements or by point mutations. Translocations and inversions involving chromosome band 16p13.3 form the minority of CBP mutations, whereas microdeletions occur more frequently (about 10%). Most deletion studies in RTS are performed by FISH analysis, and five cosmids must be used to cover the whole of the CBP gene, which spreads over 150 kb. Here we report the design of gene dosage assays by real-time quantitative PCR that are targeted on three exons located respectively at the 5' end (exon 2), in the middle (exon 12), and at the 3' end (exon 30) of the CBP gene. This technique proved to be efficient and powerful in finding deletions and complementary to the other available techniques, since it allowed us to identify deletions at the 3' end of the gene that had been missed by FISH analysis, and to refine some deletion breakpoints. Our results therefore suggest that real-time quantitative PCR is a useful technique to be included in the deletion search in RTS patients.

Molecular characterization of an 11q14.3 microdeletion associated with leukodystrophy.

Leukodystrophies represent a heterogeneous group of rare hereditary diseases affecting the central nervous system. The underlying molecular defect remains unknown in almost 50% of cases. We previously assigned a new locus for leukodystrophy of unknown cause to chromosome 11q14.3 by identifying a de novo microdeletion in a sporadic case. We now report the precise molecular characterization of this microdeletion. Physical mapping of the region of interest allowed us to identify and analyze candidate gene(s) possibly implicated in leukodystrophy.

Feasibility, accuracy and safety of chorionic villus sampling: a report of 10741 cases.

OBJECTIVES: To evaluate the feasibility, accuracy and safety of chorionic villus sampling (CVS). METHODS: Ten thousand seven hundred and forty one singleton pregnancies at risk of chromosome abnormalities (96.3%) and gene disorders (2.8%) were referred from 1990 to 1999 to the fetal medicine unit of a teaching hospital. CVS was performed transabdominally after 11 weeks, using a modified freehand ultrasonographically guided technique by 5 operators. Fetal karyotyping was obtained using a direct method before 1995 and was completed by cell culture after 1996. Failed results, feto-placental discrepancy and fetal loss were assessed. RESULTS: Villi were sampled using extra-amniotic puncture (89.4%) and one sampling-device insertion (92.3%). The mean weight of the specimen was 15.2 +/- 6.0 mg. All attempts at sampling were successful, except eight (0.07%). The number of failed results following direct preparation, cell culture and both methods was 20 (0.19%), 23 (0.21%) and 2 (0.02%), respectively. Light maternal cell contamination occurred in less than 1% of the samplings after microscopic selection of the villi, and never interfered with the assessment of karyotyping. All 3 false-negative results (0.03%) were recorded after direct preparation and 2 were corrected by culture. The rate of chromosomal abnormalities confined to the placenta decreased from 1.08% before 1995 to 0.73% after 1996. True fetal mosaicisms were recorded in 7 cases (0.06%). The rate of fetal loss at <28 weeks was 1.64% in all pregnancies and 1.92% when CVS was performed before 13 weeks. Advanced maternal age was the single factor significantly associated with fetal loss. CONCLUSIONS: CVS was feasible, accurate and safe in our institution, as a result of the increasing experience of the operators and the cytogeneticists.