Chromoanagenesis of chromosome 22 in a subject with obesity and borderline cognitive performance.

Chromoanagenesis events consist of complex chromosome rearrangements with multiple breakpoints in one or few chromosomes. Mechanisms of chromoanagenesis are split into three major groups: chromothripsis, chromoanasynthesis and chromoplexy. This study aims to delineate a chromoanagenesis event at the level of chromosome 22 in an individual showing obesity and borderline cognitive performance as major disturbances. The proband and his parents were subjected to conventional karyotyping, CGH array and whole genomic sequencing (WGS). By conventional karyotyping a "de novo" pericentric inversion of chromosome 22 was identified. CGH array identified several imbalances (either deletions or duplications) in the long arm of chromosome 22; the largest is a 4.5 Mb duplication at 22q12.1-22q1.3. The detection of extensive duplications would suggest the occurrence of a chromoanasynthesis event. WGS, in addition to the structural alterations identified by karyotyping and CGH array, revealed two translocations from chromosome 22 to chromosomes 6 and 21 as well as a heterozygous pathogenetic variant of ALMS1 gene; the latter could have contributed to the obesity of our patient. The pericentric inversion induces loss of initial part of TCF20 gene including the 5' regulatory region and the first, noncoding, exon. Heterozygous loss-of-function mutations of TCF20 gene have been found in patients with autism spectrum disorder or intellectual disability, some of them presenting obesity. It is, therefore, possible that disruption of TCF20 gene structure would contribute to a fraction of the patient's phenotype.

Effects of eEF1A1 targeting by aptamer/siRNA in chronic lymphocytic leukaemia cells.

BACKGROUND: The effectiveness of therapies for chronic lymphocytic leukemia (CLL), the most common leukemia in Western countries adults, can be improved via a deeper understanding of its molecular abnormalities. Whereas the isoforms of the eukaryotic elongation factor 1A (eEF1A1 and eEF1A2) are implicated in different tumors, no information are available in CLL. METHODS: eEF1A1/eEF1A2 amounts were quantitated in the lymphocytes of 46 CLL patients vs normal control (real time PCR, western blotting). eEF1A1 role in CLL was investigated in a cellular (MEC-1) and animal model of CLL via its targeting by an aptamer (GT75) or a siRNA (siA1) delivered by electroporation (in vitro) or lipofection (in vivo). RESULTS: eEF1A1/eEF1A2 were elevated in CLL lymphocytes vs control. eEF1A1 but not eEF1A2 levels were higher in patients which died during the study compared to those surviving. eEF1A1 targeting (GT75/siA1) resulted in MEC-1 viability reduction/autophagy stimulation and in vivo tumor growth down-regulation. CONCLUSIONS: The increase of eEF1A1 in dead vs surviving patients may confer to eEF1A1 the role of a prognostic marker for CLL and possibly of a therapeutic target, given its involvement in MEC-1 survival. Specific aptamer/siRNA released by optimized delivery systems may allow the development of novel therapeutic options.

Microduplication in the 2p16.1p15 chromosomal region linked to developmental delay and intellectual disability.

BACKGROUND: Several patients with the 2p16.1p15 microdeletion syndrome have been reported. However, microduplication in the 2p16.1p15 chromosomal region has only been reported in one case, and milder clinical features were present compared to those attributed to 2p16.1p15 microdeletion syndrome. Some additional cases were deposited in DECIPHER database. CASE PRESENTATION: In this report we describe four further cases of 2p16.1p15 microduplication in four unrelated probands. They presented with mild gross motor delay, delayed speech and language development, and mild dysmorphic features. In addition, two probands have macrocephaly and one a congenital heart anomaly. Newly described cases share several phenotype characteristics with those detailed in one previously reported microduplication case. CONCLUSION: The common features among patients are developmental delay, speech delay, mild to moderate intellectual disability and unspecific dysmorphic features. Two patients have bilateral clinodactyly of the 5th finger and two have bilateral 2nd-3rd toes syndactyly. Interestingly, as opposed to the deletion phenotype with some cases of microcephaly, 2 patients are reported with macrocephaly. The reported cases suggest that microduplication in 2p16.1p15 chromosomal region might be causally linked to developmental delay, speech delay, and mild intellectual disability.

Genomic Deletion Involving the IMMP2L Gene in Two Cases of Autism Spectrum Disorder.

Mutations/deletions of the IMMP2L gene have been associated with different cognitive/behavioral disturbances, including autism spectrum disorders (ASD). The penetrance of these defects is not complete since they often are inherited from a healthy parent. Using array-CGH in a cohort of 37 ASD patients, we found 2 subjects harboring a deletion inside the IMMP2L gene. In both cases, the IMMP2L gene deletion was inherited: from a healthy mother in one case and from a dyslectic father in the other. In the latter family, the IMMP2L deletion was also detected in the patient's brother, who showed delayed language development. In a cohort of 100 normal controls, no deletions including the IMMP2L gene were observed. However, a recent meta-analysis found no association between IMMP2L deletions and ASD. Our data would indicate that deletions involving the IMMP2L gene may contribute to the development of a subgroup of cognitive/behavioral disorders.

Familial 5q12.3 Microdeletion: Evidence for a Locus Associated with Epilepsy.

The clinical use of array comparative genomic hybridization (array CGH) has allowed the identification of very rare deletion and duplication disorders, such as 5q12 deletion syndrome (OMIM 615668) described as a contiguous gene deletion syndrome of chromosome 5q12. Chromosome microdeletions including band 5q12 have rarely been reported and have been associated with different phenotypes showing postnatal growth restriction, intellectual disability, epileptic seizures, hyperactivity, and ocular abnormalities. In this study, we describe a family in which array-CGH analysis revealed the presence of an interstitial microdeletion spanning approximately 2.9 Mb in the 5q12 region. The microdeletion is associated with epilepsy in the father and 2 siblings (a boy and a girl). So far, this is the first report in which a familial microdeletion 5q12 manifests in epilepsy. We suggest that this familial microdeletion could delineate a locus for susceptibility to epilepsy.

Clinical and pathogenic features of ETV6-related thrombocytopenia with predisposition to acute lymphoblastic leukemia.

ETV6-related thrombocytopenia is an autosomal dominant thrombocytopenia that has been recently identified in a few families and has been suspected to predispose to hematologic malignancies. To gain further information on this disorder, we searched for ETV6 mutations in the 130 families with inherited thrombocytopenia of unknown origin from our cohort of 274 consecutive pedigrees with familial thrombocytopenia. We identified 20 patients with ETV6-related thrombocytopenia from seven pedigrees. They have five different ETV6 variants, including three novel mutations affecting the highly conserved E26 transformation-specific domain. The relative frequency of ETV6-related thrombocytopenia was 2.6% in the whole case series and 4.6% among the families with known forms of inherited thrombocytopenia. The degree of thrombocytopenia and bleeding tendency of the patients with ETV6-related thrombocytopenia were mild, but four subjects developed B-cell acute lymphoblastic leukemia during childhood, resulting in a significantly higher incidence of this condition compared to that in the general population. Clinical and laboratory findings did not identify any particular defects that could lead to the suspicion of this disorder from the routine diagnostic workup. However, at variance with most inherited thrombocytopenias, platelets were not enlarged. In vitro studies revealed that the maturation of the patients' megakaryocytes was defective and that the patients have impaired proplatelet formation. Moreover, platelets from patients with ETV6-related thrombocytopenia have reduced ability to spread on fibrinogen. Since the dominant thrombocytopenias due to mutations in RUNX1 and ANKRD26 are also characterized by normal platelet size and predispose to hematologic malignancies, we suggest that screening for ETV6, RUNX1 and ANKRD26 mutations should be performed in all subjects with autosomal dominant thrombocytopenia and normal platelet size.

Microdeletion 15q26.2qter and Microduplication 18q23 in a Patient with Prader-Willi-Like Syndrome: Clinical Findings.

The small interstitial deletion in the long arm of chromosome 15 causing Prader-Willi/Angelman syndrome is well known, whereas cases that report terminal deletions in 15q in association with the Prader-Willi-like phenotype are very rare. By using GTG-banding analysis, metaphase FISH, MLPA analysis, and genome-wide array CGH, we detected an unbalanced translocation involving a microdeletion of the distal part of 15q and a microduplication of the distal part of 18q. The unbalanced translocation was found in a boy that was referred with clinical suspicion of Prader-Willi syndrome. In the 15q-deleted region, 23 genes have been identified, and 13 of them are included in the OMIM database. Among these, the deleted IGFR1, MEF2A, CHSY1, and TM2D3 genes could contribute to the patient's phenotype. Seven genes are included in the duplicated chromosome segment 18q, but only one (CTDP1) is present in the OMIM database. We suggest that the deleted chromosome segment 15q26.2qter may be responsible for the phenotype of our case and may also be a candidate locus of Prader-Willi-like syndrome.

Germline mutations in ETV6 are associated with thrombocytopenia, red cell macrocytosis and predisposition to lymphoblastic leukemia.

Some familial platelet disorders are associated with predisposition to leukemia, myelodysplastic syndrome (MDS) or dyserythropoietic anemia. We identified a family with autosomal dominant thrombocytopenia, high erythrocyte mean corpuscular volume (MCV) and two occurrences of B cell-precursor acute lymphoblastic leukemia (ALL). Whole-exome sequencing identified a heterozygous single-nucleotide change in ETV6 (ets variant 6), c.641C>T, encoding a p.Pro214Leu substitution in the central domain, segregating with thrombocytopenia and elevated MCV. A screen of 23 families with similar phenotypes identified 2 with ETV6 mutations. One family also had a mutation encoding p.Pro214Leu and one individual with ALL. The other family had a c.1252A>G transition producing a p.Arg418Gly substitution in the DNA-binding domain, with alternative splicing and exon skipping. Functional characterization of these mutations showed aberrant cellular localization of mutant and endogenous ETV6, decreased transcriptional repression and altered megakaryocyte maturation. Our findings underscore a key role for ETV6 in platelet formation and leukemia predisposition.

Mutations in ANKRD26 are responsible for a frequent form of inherited thrombocytopenia: analysis of 78 patients from 21 families.

Until recently, thrombocytopenia 2 (THC2) was considered an exceedingly rare form of autosomal dominant thrombocytopenia and only 2 families were known. However, we recently identified mutations in the 5'-untranslated region of the ANKRD26 gene in 9 THC2 families. Here we report on 12 additional pedigrees with ANKRD26 mutations, 6 of which are new. Because THC2 affected 21 of the 210 families in our database, it has to be considered one of the less rare forms of inherited thrombocytopenia. Analysis of all 21 families with ANKRD26 mutations identified to date revealed that thrombocytopenia and bleeding tendency were usually mild. Nearly all patients had no platelet macrocytosis, and this characteristic distinguishes THC2 from most other forms of inherited thrombocytopenia. In the majority of cases, platelets were deficient in glycoprotein Ia and α-granules, whereas in vitro platelet aggregation was normal. Bone marrow examination and serum thrombopoietin levels suggested that thrombocytopenia was derived from dysmegakaryopoiesis. Unexplained high values of hemoglobin and leukocytes were observed in a few cases. An unexpected finding that warrants further investigation was a high incidence of acute leukemia. Given the scarcity of distinctive characteristics, the ANKRD26-related thrombocytopenia has to be taken into consideration in the differential diagnosis of isolated thrombocytopenias.

Mutations in the 5' UTR of ANKRD26, the ankirin repeat domain 26 gene, cause an autosomal-dominant form of inherited thrombocytopenia, THC2.

THC2, an autosomal-dominant thrombocytopenia described so far in only two families, has been ascribed to mutations in MASTL or ACBD5. Here, we show that ANKRD26, another gene within the THC2 locus, and neither MASTL nor ACBD5, is mutated in eight unrelated families. ANKRD26 was also found to be mutated in the family previously reported to have an ACBD5 mutation. We identified six different ANKRD26 mutations, which were clustered in a highly conserved 19 bp sequence located in the 5' untranslated region. Mutations were not detected in 500 controls and are absent from the 1000 Genomes database. Available data from an animal model and Dr. Watson's genome give evidence against haploinsufficiency as the pathogenetic mechanism for ANKRD26-mediated thrombocytopenia. The luciferase reporter assay suggests that these 5' UTR mutations might enhance ANKRD26 expression. ANKRD26 is the ancestor of a family of primate-specific genes termed POTE, which have been recently identified as a family of proapoptotic proteins. Dysregulation of apoptosis might therefore be the pathogenetic mechanism, as demonstrated for another thrombocytopenia, THC4. Further investigation is needed to provide evidence supporting this hypothesis.