Search

Syndromic obesity is defined by the association of obesity with one or more feature(s) including developmental delay, dysmorphic traits, and/or congenital malformations. Over 25 syndromic forms of obesity have been identified. However, most cases remain of unknown etiology. The aim of this study was to identify new candidate loci associated with syndromic obesity to find new candidate genes and to better understand molecular mechanisms involved in this pathology. We performed oligonucleotide microarray-based comparative genomic hybridization in a cohort of 100 children presenting with syndromic obesity of unknown etiology, after exhaustive clinical, biological, and molecular studies. Chromosomal copy number variations were detected in 42% of the children in our cohort, with 23% of patients with potentially pathogenic copy number variants. Our results support that chromosomal rearrangements are frequently associated with syndromic obesity with a variety of contributory genes having relevance to either obesity or developmental delay. A list of inherited or apparently de novo duplications and deletions including their enclosed genes and not previously linked to syndromic obesity was established. Proteins encoded by several of these genes are involved in lipid metabolism (ACOXL, MSMO1, MVD, and PDZK1) linked with nervous system function (BDH1 and LINGO2), neutral lipid storage (PLIN2), energy homeostasis and metabolic processes (CDH13, CNTNAP2, CPPED1, NDUFA4, PTGS2, and SOCS6).

Thirty patients have been described with cytogenetically visible deletion of the short arm of chromosome 6. However, subtelomeric 6p deletion detected by subtelomeric specific probes has been reported only twice. We report two new patients with terminal 6p deletion detected by subtelomeric screening using fluorescence in situ hybridization (FISH). The two patients exhibited mental retardation, ocular abnormalities, hearing loss, and a characteristic facial appearance. Detailed FISH analyses with probes covering the distal 6p25 region estimated the size of the terminal deletions to approximately 5.5 Mb and approximately 4.8 Mb. Array-based comparative genomic hybridization (array CGH) was used to confirm the cryptic deletions. Most patients with subtelomeric defects lack a characteristic phenotype. However, some of the subtelomeric deletions result in a specific phenotype, which can direct the clinician towards the diagnosis. Submicroscopic 6p deletion appears to be a recognizable clinical phenotype, and this region should be thoroughly investigated with FISH probes, including at least a subtelomeric 6p probe and a probe covering FOXC1, for patients presenting with a characteristic facial appearance, ocular abnormalities, predominantly anterior-chamber eye defects, hearing loss, and mental retardation.

The Albright hereditary osteodystrophy-like (AHO-like) syndrome was recently defined as a rare dysmorphic syndrome including brachymetaphalangism and mental retardation. This phenotype occurs in Albright hereditary osteodystrophy (AHO) but unlike it, the level of the Gs alpha protein activity is not reduced. To date 59 patients with these clinical and biochemical features have been reported, and for the majority of them (57/59) a cytogenetically visible 2q37 deletion has been observed. We report a new case of typical AHO-like syndrome with normal karyotype. Using the polymorphic marker D2S125 we found a loss of heterozygosity suggestive of a de novo 2q37 deletion of maternal origin. This hypothesis was confirmed by FISH analysis with a subtelomeric 2q probe containing the D2S90 marker. Genotypic analysis allowed us to map the proximal breakpoint of the subtelomeric deletion within an interval delimited by D2S2338 (present) and D2S2253 (deleted). This 2q subtelomeric deletion as small as 4 Mb is to date the smallest one observed in association with a typical AHO-like phenotype, and allows us to move the centromeric boundary of the AHO-like critical region by 750 kb towards the 2q telomere.

Background : The normal levels of alkaline phosphatase (AP) activity in maternal serum are virtually the same as those observed in Down syndrome (DS) pregnancies at 14–20 weeks' gestation. Using urea inhibition of AP, we observed an atypical AP isoenzyme in the neutrophils of mothers with trisomy 21 fetuses. Aim : To assess the use of urea as a selective inhibitor of serum AP in order to seek a possible diagnostic difference between normal and DS pregnancies. Study Design and Subjects : Serum AP samples from 24 DS pregnancies and 204 control cases were examined at 12–22 weeks' gestation with and without 2.5 M urea AP inhibition at 18 °C for 2 h. The levels of AP activity obtained without urea and the percentage urea AP inhibition were analyzed in the two groups. Results : Without urea treatment, no significant difference of total alkaline phosphatase activity levels was detected between the 204 normal controls and the 24 DS samples. Using 2.5 M urea AP inhibition, after 120 min of exposure at 18 °C, the residual activity, as a percentage of initial values of AP, showed significantly higher resistance in the DS samples (≥50 IU/l of total AP activity) at 15–22 weeks' gestation. However, at 12–14 weeks (≤45 IU/l of total AP activity), no significant difference was found between the DS and control cases. Conclusion : Serum urea resistant alkaline phosphatase in DS pregnancies showed a significant difference only at 15–22 weeks' gestation, compared with normal controls.

Testicular cancer is the most common neoplasia occurring in the young male population. The PEB (cisplatin, etoposide and bleomycin) adjuvant chemotherapy usually proposed after orchidectomy in non seminomatous tumours, and in metastatic seminomas, has improved the long-term survival of these patients. Following an azoospermic period, sperm cell recovery is generally observed after treatment delivery, but little is known about the genetic consequences on these new spermatozoa. To estimate the chromosomal consequences of this chemotherapy on sperm cells during the period of recovery of spermatogenesis, sperm cell aneuploidy was studied in testicular cancer patients, at 6-18 months after PEB adjuvant chemotherapy delivery, using fluorescence in-situ hybridization (FISH) of chromosomes 7, 16, 18, X and Y with specific DNA probes. A significant increase in the frequency of diploidy and disomy for chromosomes 16, 18 and XY was observed in treated patients compared with a healthy control group. Spermatozoa aneuploidy occurring during the spermatogenesis recovery period might be a possible side effect of the PEB regimen. Thus, practitioners should be advised to provide counselling about the need for an appropriate duration of contraception. Moreover, genetic counselling should be offered in cases of pregnancy occurring soon after the end of chemotherapy.

Microdeletions of the long arm of the Y chromosome (Yq) are a common cause of male infertility. Since large structural rearrangements of the Y chromosome are commonly associated with a 45,XO/46,XY chromosomal mosaicism, we studied whether submicroscopic Yq deletions could also be associated with the development of 45,XO cell lines. We studied blood samples from 14 infertile men carrying a Yq microdeletion as revealed by polymerase chain reaction (PCR). Patients were divided into two groups: group 1 (n = 6), in which karyotype analysis demonstrated a 45,X/46,XY mosaicism, and group 2 (n = 8) with apparently a normal 46,XY karyotype. 45,XO cells were identified by fluorescence in-situ hybridization (FISH) using X and Y centromeric probes. Lymphocytes from 11 fertile men were studied as controls. In addition, sperm cells were studied in three oligozoospermic patients in group 2. Our results showed that large and submicroscopic Yq deletions were associated with significantly increased percentages of 45,XO cells in lymphocytes and of sperm cells nullisomic for gonosomes, especially for the Y chromosome. Moreover, two isodicentric Y chromosomes, classified as normal by cytogenetic methods, were detected. Therefore, Yq microdeletions may be associated with Y chromosomal instability leading to the formation of 45,XO cell lines.

Quantitative and qualitative analysis of alkaline phosphatases (AP) was performed on amniotic fluid in 59 normal pregnancies and 14 Down's syndrome (DS) pregnancies at 16, 18 and 19 weeks of gestation. In DS cases, intestinal and placental isoenzyme levels were significantly reduced (P

International audience; Genetics of Holoprosencephaly (HPE), a congenital malformation of the developing human forebrain, is due to multiple genetic defects. Most genes that have been implicated in HPE belong to the sonic hedgehog signaling pathway. Here we describe a new candidate gene isolated from array comparative genomic hybridization redundant 6qter deletions, DELTA Like 1 (DLL1), which is a ligand of NOTCH. We show that DLL1 is co-expressed in the developing chick forebrain with Fgf8. By treating chick embryos with a pharmacological inhibitor, we demonstrate that DLL1 interacts with FGF signaling pathway. Moreover, a mutation analysis of DLL1 in HPE patients revealed a three-nucleotide deletion. These various findings implicate DLL1 in early patterning of the forebrain and identify NOTCH as a new signaling pathway involved in HPE.

In a search for potential infertility loci, which might be revealed by clustering of chromosomal breakpoints, we compiled 464 infertile males with a balanced rearrangement from Mendelian Cytogenetics Network database (MCNdb) and compared their karyotypes with those of a Danish nation-wide cohort. We excluded Robertsonian translocations, rearrangements involving sex chromosomes and common variants. We identified 10 autosomal bands, five of which were on chromosome 1, with a large excess of breakpoints in the infertility group. Some of these could potentially harbour a male-specific infertility locus. However, a general excess of breakpoints almost everywhere on chromosome 1 was observed among the infertile males: 26.5 versus 14.5% in the cohort. This excess was observed both for translocation and inversion carriers, especially pericentric inversions, both for published and unpublished cases, and was significantly associated with azoospermia. The largest number of breakpoints was reported in 1q21; FISH mapping of four of these breakpoints revealed that they did not involve the same region at the molecular level. We suggest that chromosome 1 harbours a critical domain whose integrity is essential for male fertility.

Primary microcephaly (microcephalia vera) is a developmental abnormality resulting in a small brain, with mental retardation. It is usually transmitted as an autosomal recessive trait, and six loci have been reported to date. We analyzed a translocation breakpoint previously reported in a patient with apparently sporadic primary microcephaly, at 1q31, where locus MCPH5 maps. The patient was lost to follow-up, and we sampled a maternal aunt who carried the familial translocation. FISH analyses showed that the insert of BAC clone RP11-32D17 spanned the breakpoint. The breakpoint was further located within a fragment of this insert corresponding to intron 17 of the ASPM gene, resulting in a predicted transcript truncated of more than half of its coding sequence. It is very likely that the proband carried a second ASPM mutation in trans, but he was not available for sampling and hence we could not confirm this hypothesis. Our observation adds to the mutation spectrum of ASPM in primary microcephaly, and is to our knowledge the second example of a constitutional, reciprocal translocation responsible for a bona fide autosomal recessive phenotype.

Intensive studies have been conducted so far on biochemical markers available for screening of chromosome defects in obstetrical monitoring. In this paper we report further data on two protein phosphatases: alkaline phosphatase (a marker of cell maturation) and phosphotyrosine phosphatase (a marker of cell proliferation) assayed in cultured amniotic cells from fetuses with trisomy 18 at 15 weeks of gestation. Comparison with normal fetal cells showed a different behaviour for each enzyme: alkaline phosphatase was very significantly lowered while phosphotyrosine phosphatase remained at normal levels. These results provide a further enlargement of the field of biochemical markers used in the screening tests of trisomy 18.

We report a follow-up of 49 children with acute lymphoblastic leukemia (ALL) diagnosed between 1972 and 1978 (follow-up 12–18 years). This series allowed us to analyze the predictive value of karyotype in a long-term follow-up. Karyotypes were abnormal in 33 cases (67.3%): pseudodiploidy in 11 (22.4%), hyperdiploidy > 50 chromosomes in 8 (16.3%), hyperdiploidy 47–50 chromosomes in 11 (22.4%), and hypodiploidy in 3 cases (6.1%). Event-free survival (EFS) and survival studies showed that the outcome of patients was determined only by treatment and karyotype. Eleven patients have survived, nine in first remission (6 years 5 months to 15 years 2 months), and two are in second remission (3 years 8 months and 8 years 2 months). All ploidy groups are represented in these patients. Late relapses can occur in the hyperdiploid > 50 group, thus accounting for shorter EFS than expected, but because of the unusually long second remission of one patient, the rate of surviving patients was higher for this ploidy group than for all other ploidy groups together. Conversely, patients with only numerical abnormalities (no matter which ploidy group they belonged to), had a better outcome than did patients with structural changes or normal karyotypes and no discrepancy between EFS and survival curves was observed in this chromosomal group. Thus, our results suggest that numerical changes only should be considered an indicator of low risk factor, but our results, based on partially banded karyotypes, need to be verified by a current method and therapy.

A patient with chronic myeloid leukemia showed clonal karyotypic evolution, with the appearance of an i(17q) and t(9;11)(p22;q23). This case sheds light upon leukemogenic events related to t(9;11)(p22;q23). The presence of t(9;22) and t(9;11) in the same clone showed that t(9;11) may affect a pluripotent stem cell, thus accounting for t(9;11) in both lymphoid and monocytic leukemias. In this patient, t(9;11) could not be related to a prior cytotoxic exposure and was instead the result of natural evolution of chronic myeloid leukemia. Furthermore, this led us to assume that the phenotype of blast cells may be determined by a chromosome abnormality. A phenotypic conversion from myeloblastic to undifferentiated morphologic aspect was observed when t(9;11) was detected, suggesting that t(9;11) may have induced a loss in differentiation of blast cells affected by this change. This assumption is in agreement with the putative presence of genes activated in pluripotent progenitors by 11q23 rearrangements.

The common clinical features reported in ring chromosome 22 cases include overall developmental delay with severe speech disability, growth retardation with frequently associated microcephaly, hypotonia, and dysmorphic traits, such as epicanthus, normally placed but large and dysplastic ears, long eyelashes with full eyebrows, and occasionally high arched palate, dental malocclusion, and mild hypertelorism.1–9 Second and third toe syndactyly, unsteady gait, hyperactivity, aggressive behaviour, autistic disorders,3, 4 and seizures or abnormal EEG1, 2 have also been reported. The recently described subtelomeric 22q deletion syndrome showed overlapping clinical features with a generalised developmental delay, particularly severe in the area of expressive speech.10–14 The phenotype is usually more severe in cases of ring chromosome 22 compared with subtelomeric 22q deletions. The phenotypic differences, particularly the growth retardation with microcephaly and the severe mental delay, could be the result of a larger deletion size in ring chromosome 22 cases. We report the molecular cytogenetic analysis of a ring chromosome 22 in a young boy investigated for global development and severe speech delay. This is the first molecular analysis of a ring chromosome 22 harbouring the second smallest 22qter microdeletion reported so far. Characteristics of cases with ring chromosome 22 and subtelomeric 22q deletion are reviewed. ### Case report The patient, a 7 year old boy, was seen for evaluation of global developmental delay. He was born to healthy, non-consanguineous parents aged 35 (mother) and 39 (father) years. His two older sisters were normal. Pregnancy, delivery, and the neonatal period were uneventful. His birth weight was 3330 g (50th centile), length was 50 cm (25th centile), and head circumference was …

A patient developed a secondary blood disorder 7 years after radiotherapy for a gastric lymphoma. The initial myelodysplastic syndrome evolved to a myeloproliferative phase with transient polycythemia, progressive thrombocythemia, and hyperleukocytosis. Chromosome analysis performed in the terminal phase showed del(5)(q13q31),t(9;22)(q34;q11), and a complex rearrangement involving chromosomes #2 and #3. A correlation between chromosomal abnormalities and hematologic findings could be established. In this case, we have assumed that the Philadelphia translocation is a late event, due to prior mutagen exposure, and its association with a common secondary abnormality (5q−), followed by a progressively developing myeloproliferative phase. Furthermore, the association of Ph and 5q− in a single clone seems to indicate that the same stem cell is affected by these two abnormalities.

A blastic crisis of chronic myeloid leukemia without a detectable chronic phase is reported. At diagnosis, blast cells present t(9;22)(q34;q11),t(14;14)(q11;q32) translocations and early B cell phenotype (DR +, TdT +, B4 +, BA1 +, J5 +). At relapse, the malignant clone evolves to a biphenotypic expression, the initial markers remain unchanged, and two myeloid antigens (My 7, My 9) appear. The wide overlap in percentages of blast cells displaying lymphoid and myeloid markers shows that a single clone bears antigens of both lineages. Simultaneous occurrence of a t(14;14)(q11;q32) translocation, usually found in T cell malignancies, and of a B cell phenotype raises the question of the relationship between chromosomal changes and surface marker expression. The malignant cell is assumed to be a progenitor cell, already committed to lymphoid lineage and retaining the potential to switch to myeloid lineage.

This report describes a new case of chronic myeloid leukemia with an unusual Philadelphia chromosome translocation involving chromosomes No. 4,9, and 22; t(4,9,22) (q31;q34;q11).