Delineation of MidXq28-duplication syndrome distal to MECP2 and proximal to RAB39B genes.

Two distinct genomic disorders have been linked to Xq28-gains, namely Xq28-duplications including MECP2 and Int22h1/Int22h2-mediated duplications involving RAB39B. Here, we describe six unrelated patients, five males and one female, with Xq28-gains distal to MECP2 and proximal to the Int22h1/Int22h2 low copy repeats. Comparison with patients carrying overlapping duplications in the literature defined the MidXq28-duplication syndrome featuring intellectual disability, language impairment, structural brain malformations, microcephaly, seizures and minor craniofacial features. The duplications overlapped for 108 kb including FLNA, RPL10 and GDI1 genes, highly expressed in brain and candidates for the neurologic phenotype.

Small 4p16.3 deletions: Three additional patients and review of the literature.

Wolf-Hirschhorn syndrome is a well-defined disorder due to 4p16.3 deletion, characterized by distinct facial features, intellectual disability, prenatal and postnatal growth retardation, and seizures. Genotype-phenotype correlations based on differently sized deletions have been attempted, and some candidate genes have been suggested. We report on clinical characteristics of three patients with pure interstitial submicroscopic 4p16.3 deletions, ranging in size from 68 to 166 kb, involving WHSCR1 and/or part of WHSCR2, and review published cases with overlapping 4p16.3 losses. The present study highlights a major role of NSD2 gene in the pathogenesis of the WHS main features and predicts that loss-of-function mutations affecting NSD2 gene could result in microcephaly, prenatal and postnatal growth retardation, psychomotor and language delay, and craniofacial features. Absent seizures in all subjects corroborate the suggestion that this specific feature is causally linked with at least one additional causative gene. Finally, we suggest that mir-943 could play a role in the pathogenesis of CHD in some of these patients.

A Small Supernumerary Marker Derived from the Pericentromeric Region of Chromosome 5: Case Report and Delineation of Partial Trisomy 5p Phenotype.

A 17-year-old girl presented with a distinct phenotype mainly featuring craniofacial dysmorphism, including a disproportioned large, round, elongated face; hypertelorism; deep-set eyes with short palpebral fissures; obesity (BMI 37), and a neuropsychiatric disorder with high-functioning autism. Postnatal conventional cytogenetic analyses from peripheral blood revealed a mosaic small supernumerary marker chromosome (sSMC) with a mos 47,XX,+mar[7]/46,XX[43] karyotype. By cenM-FISH technique, the sSMC was identified as a ring derivative of chromosome 5. Metaphase FISH analysis with a set of dedicated probes defined its origin from the pericentromeric region of chromosome 5, including the NIPBL gene at 5p13.2. Such sSMCs, exceedingly rare in the literature, underlie proximal trisomy 5p. In order to delineate a core phenotype of proximal trisomy 5p, we compared our patient's features with those of 6 patients found in the literature with similar der(5) chromosomes. Furthermore, a dozen individuals with 5p13 (micro)duplication syndrome was compared and discussed. We identified highly distinctive craniofacial dysmorphism, obesity, and intellectual disability and/or autism spectrum disorder as typical features of proximal 5p trisomy. In the critical region (band 5p13), the NIPBL gene is likely to be a major determinant of the neurobehavioral phenotype, and its presence at the sSMC level may be relevant to predict clinical outcome.

First evidence of Smith-Magenis syndrome in mother and daughter due to a novel RAI mutation.

Smith-Magenis syndrome (SMS) is a complex genetic disorder caused by interstitial 17p11.2 deletions encompassing multiple genes, including the retinoic acid induced 1 gene-RAI1-or mutations in RAI1 itself. The clinical spectrum includes developmental delay, cognitive impairment, and behavioral abnormalities, with distinctive physical features that become more evident with age. No patients have been reported to have had offspring. We here describe a girl with developmental delay, mainly compromising the speech area, and her mother with mild intellectual disabilities and minor dysmorphic features. Both had sleep disturbance and attention deficit disorder, but no other atypical behaviors have been reported. In both, CGH-array analysis detected a 15q13.3 interstitial duplication, encompassing CHRNA7. However, the same duplication has been observed in several, apparently healthy, maternal relatives. We, thus, performed a whole exome sequencing analysis, which detected a frameshift mutation in RAI1, de novo in the mother, and transmitted to her daughter. No other family members carried this mutation. This is the first report of an SMS patient having offspring. Our experience confirms the importance of searching for alternative causative genetic mechanisms in case of confounding/inconclusive findings such as a CGH-array result of uncertain significance. © 2016 Wiley Periodicals, Inc.

Oct-1 recruitment to the nuclear envelope in adult-onset autosomal dominant leukodystrophy.

Adult-onset autosomal dominant leukodystrophy (ADLD) is a slowly progressive neurological disorder characterised by pyramidal, cerebellar, and autonomic disturbances. Duplication of the LMNB1 gene is the genetic cause of ADLD, yet the pathogenetic mechanism is not defined. In this study, we analysed cells and muscle tissue from three patients affected by ADLD, carrying an extra copy of the LMNB1 gene. Lamin B1 levels were dramatically increased in ADLD nuclei, both in skin fibroblasts and skeletal muscle fibres. Since lamin B1 is known to bind Oct-1, a transcription factor involved in the oxidative stress pathway, we investigated Oct-1 fate in ADLD. Oct-1 recruitment to the nuclear periphery was increased in ADLD cells, while nucleoplasmic localisation of the transcription factor under oxidative stress conditions was reduced. Importantly, lamin B1 degradation occurring in some, but not all ADLD cell lines, slowed down lamin B1 and Oct-1 accumulation. In skeletal muscle, focal disorganisation of sarcomeres was observed, while IIB-myosin heavy chain, an Oct-1 target gene, was under-expressed and rod-containing fibres were formed. These data show that a high degree of regulation of lamin B1 expression is implicated in the different clinical phenotypes observed in ADLD and show that altered Oct-1 nuclear localisation contributes to the disease phenotype.

Retinoic acid-induced 1 gene haploinsufficiency alters lipid metabolism and causes autophagy defects in Smith-Magenis syndrome.

Smith-Magenis syndrome (SMS) is a neurodevelopmental disorder characterized by cognitive and behavioral symptoms, obesity, and sleep disturbance, and no therapy has been developed to alleviate its symptoms or delay disease onset. SMS occurs due to haploinsufficiency of the retinoic acid-induced-1 (RAI1) gene caused by either chromosomal deletion (SMS-del) or RAI1 missense/nonsense mutation. The molecular mechanisms underlying SMS are unknown. Here, we generated and characterized primary cells derived from four SMS patients (two with SMS-del and two carrying RAI1 point mutations) and four control subjects to investigate the pathogenetic processes underlying SMS. By combining transcriptomic and lipidomic analyses, we found altered expression of lipid and lysosomal genes, deregulation of lipid metabolism, accumulation of lipid droplets, and blocked autophagic flux. We also found that SMS cells exhibited increased cell death associated with the mitochondrial pathology and the production of reactive oxygen species. Treatment with N-acetylcysteine reduced cell death and lipid accumulation, which suggests a causative link between metabolic dyshomeostasis and cell viability. Our results highlight the pathological processes in human SMS cells involving lipid metabolism, autophagy defects and mitochondrial dysfunction and suggest new potential therapeutic targets for patient treatment.

Testing single/combined clinical categories on 5110 Italian patients with developmental phenotypes to improve array-based detection rate.

BACKGROUND: Chromosomal microarray analysis (CMA) is nowadays widely used in the diagnostic path of patients with clinical phenotypes. However, there is no ascertained evidence to date on how to assemble single/combined clinical categories of developmental phenotypic findings to improve the array-based detection rate. METHODS: The Italian Society of Human Genetics coordinated a retrospective study which included CMA results of 5,110 Italian patients referred to 17 genetics laboratories for variable combined clinical phenotypes. RESULTS: Non-polymorphic copy number variants (CNVs) were identified in 1512 patients (30%) and 615 (32%) present in 552 patients (11%) were classified as pathogenic. CNVs were analysed according to type, size, inheritance pattern, distribution among chromosomes, and association to known syndromes. In addition, the evaluation of the detection rate of clinical subgroups of patients allowed to associate dysmorphisms and/or congenital malformations combined with any other single clinical sign to an increased detection rate, whereas non-syndromic neurodevelopmental signs and non-syndromic congenital malformations to a decreased detection rate. CONCLUSIONS: Our retrospective study resulted in confirming the high detection rate of CMA and indicated new clinical markers useful to optimize their inclusion in the diagnostic and rehabilitative path of patients with developmental phenotypes.

Identification of i(X)(p10) as the sole molecular abnormality in atypical chronic myeloid leukemia evolved into acute myeloid leukemia.

The World Health Organization classifies atypical chronic myeloid leukemia (aCML) as a myeloproliferative/myelodisplastic hematological disorder. The primary manifestations are leukocytosis with disgranulopoiesis, absence of basophilia and/or monocytosis, splenomegaly and absence of Philadelphia chromosome or BCR/ABL fusion. Overall 50-65% of patients demonstrate karyotypic abnormalities, although no specific cytogenetic alterations have been associated with this disease. X chromosome alterations have been rarely reported in myeloid malignancies. Although Isodicentric X, idic(X)(q13) is well known in females with myelodysplastic syndromes (MDS), little data are available on X isochromosome and its pathogenetic potential in these disorders. i(X)(p10) is observed in a variety of hematologic malignancies, both myeloid and lymphoid, as a unique abnormality, as well as part of a more complex karyotype, in females and less frequently in male patients. The present report describes the first patient with aCML, with documented isolated i(X)(p10), who developed a secondary acute myeloid leukemia (sAML).

Molecular cytogenetics characterization of seven small supernumerary marker chromosomes derived from chromosome 19: Genotype-phenotype correlation and review of the literature.

Only a few subjects carrying supernumerary marker chromosomes derived from 19 chromosome (sSMC(19)) have been described to date and for a small portion of them the genic content has been defined at the molecular level. We present seven new different sSMCs(19) identified in eight individuals, seven of whom unrelated. The presence of the sSMC is associated with a clinical phenotype in five subjects, while the other three carriers, two of whom related, are normal. All sSMCs(19) have been characterized by means of conventional and molecular cytogenetics. We compare the sSMCs(19) carriers with a clinical phenotype to already described patients with gains (sSMCs or microduplications) of overlapping genomic regions with the aim to deepen the pathogenicity of the encountered imbalances and to assess the role of the involved genes on the phenotype. The present work supports the correlation between the gain of some chromosome 19 critical regions and specific phenotypes.

Copy number variations in healthy subjects. Case study: iPSC line CSSi005-A (3544) production from an individual with variation in 15q13.3 chromosome duplicating gene CHRNA7.

CHRNA7, encoding the neuronal alpha7 nicotinic acetylcholine receptor (a7nAChR), is highly expressed in the brain, particularly in the hippocampus. It is situated in the 15q13.3 chromosome region, frequently associated with a Copy Number Variation (CNV), which causes its duplication or deletion. The clinical significance of CHRNA7 duplications is unknown so far, but there are several research data suggesting that they may be pathogenic, with reduced penetrance. We have produced an iPS cell line from a single healthy donor's fibroblasts carrying a 15q13.3 CNV, including CHRNA7 in order to study the exact role of this CNV during the neurodevelopment.

Four Copies of SNCA Responsible for Autosomal Dominant Parkinson's Disease in Two Italian Siblings.

Background. Parkinson's disease (PD) is mostly characterized by alpha-synuclein (SNCA) aggregation and loss of nigrostriatal dopamine-containing neurons. In this study a novel SNCA multiplication is described in two siblings affected by severe parkinsonism featuring early onset dyskinesia, psychiatric symptoms, and cognitive deterioration. Methods. SNCA dosage was performed using High-Density Comparative Genomic Hybridization Array (CGH-Array), Multiple Ligation Dependent Probe Amplification (MLPA), and Quantitative PCR (qPCR). Genetic analysis was associated with clinical evaluation. Results. Genetic analysis of siblings showed for the first time a 351 Kb triplication containing SNCA gene along with 6 exons of MMRN1 gene in 4q22.1 and a duplication of 1,29 Mb of a genomic region flanking the triplication. Conclusions. The identification of this family indicates a novel mechanism of SNCA gene multiplication, which confirms the genomic instability in this region and provides data on the genotype-phenotype correlation in PD patients.

De novo 13q13.3-21.31 deletion involving RB1 gene in a patient with hemangioendothelioma of the liver.

Interstitial deletions of the long arm of chromosome 13 (13q) are related with variable phenotypes, according to the size and the location of the deleted region. The main clinical features are moderate/severe mental and growth retardation, cranio-facial dysmorphism, variable congenital defects and increased susceptibility to tumors. Here we report a 3-year-old girl carrying a de novo 13q13.3-21.32 interstitial deletion. She showed developmental delay, growth retardation and mild dysmorphism including curly hair, high forehead, short nose, thin upper lip and long philtrum. An abnormal mass was surgically removed from her liver resulting in a hemangioendothelioma. Array analysis allowed us to define a deleted region of about 27.87 Mb, which includes the RB1 gene. This is the first report of a 13q deletion associated with infantile hemangioendothelioma of the liver.

Transabdominal coelocentesis as early source of fetal DNA for chromosomal and molecular diagnosis.

This study reports a comparative analysis between results of transabdominal coelocentesis and traditional invasive procedure in order to assess the usefulness of coelocentesis as a source of fetal DNA for molecular and chromosomal analysis. A number of 28 women were included in the study. A successful sampling of coelomic fluid was obtained in 25 women by transabdominal procedure. A positive amplification of DNA with QF-PCR techniques was obtained in 90% of cases, while 10% of cases failed to reveal interpretable results. Although all samples were cultured, the growth rate was not sufficient to determine karyotypes within 2 weeks. Five samples were selected to be analyzed by array-based comparative genomic hybridization (a-CGH) but the interpretation of these results was difficult and ambiguous. Our results suggest that transabdominal coelocentesis is suitable for the detection of single DNA variation and for QF-PCR analysis, while further experiments are needed to develop optimized protocols for traditional karyotyping and array-analysis.

De novo mosaic ring chromosome 18 in a child with mental retardation, epilepsy and immunological problems.

Ring chromosome 18 [r(18)] is a disorder in which one or both ends of chromosome 18 are lost and joined forming a ring-shaped figures. R(18) patients can therefore show features of 18q-, 18p- syndrome or a combination of both, depending on the size of the 18p and 18q deleted regions. The phenotype of the r(18) is characterized by developmental delay/mental retardation, typical facial dysmorphisms, major abnormalities and immunological problems. Here we report a case of de novo mosaic r(18) with a characterization by array-based comparative genomic hybridization analysis, and discuss the phenotypic correlation in r(18) also through a comparison with previously described cases of the literature.