A New Intronic Variant in ECEL1 in Two Patients with Distal Arthrogryposis Type 5D.

Distal Arthrogryposis type 5D (DA5D) is characterized by congenital contractures involving the distal joints, short stature, scoliosis, ptosis, astigmatism, and dysmorphic features. It is inherited in an autosomal recessive manner, and it is a result of homozygous or compound heterozygous variants in the ECEL1 gene. Here, we report two patients of Sardinian origin harboring a new intronic homozygous variant in ECEL1 (c.1507-9G>A), which was predicted to affect mRNA splicing by activating a cryptic acceptor site. The frequency of the variant is very low in the general human population, and its presence in our families can be attributed to a founder effect. This study provides an updated review of the known causative mutations of the ECEL1 gene, enriching the allelic spectrum to include the noncoding sequence.

Autism and severe clinical phenotype in a patient with 8p21.2p11.21 deletion: Case report and literature review.

Interstitial 8p deletions were previously described, in literature and databases, in approximately 30 patients with neurodevelopmental disorders. We report on a novel patient with a 8p21.2p11.21 deletion presenting a clinical phenotype that includes severe intellectual disability, microcephaly, epilepsy, and autism, the latter having been rarely associated with this genetic defect.

Extensive molecular analysis suggested the strong genetic heterogeneity of idiopathic chronic pancreatitis.

Rationale: Genetic features of Chronic Pancreatitis (CP) have been extensively investigated mainly testing genes associated to the trypsinogen activation pathway. However, different molecular pathways involving other genes may be implicated in CP pathogenesis. Objectives: 80 patients with Idiopathic CP were investigated using Next Generation Sequencing approach with a panel of 70 genes related to six different pancreatic pathways: premature activation of trypsinogen; modifier genes of Cystic Fibrosis phenotype; pancreatic secretion and ion homeostasis; Calcium signalling and zymogen granules exocytosis; autophagy; autoimmune pancreatitis related genes. Results: We detected mutations in 34 out of 70 genes examined; 64/80 patients (80.0%) were positive for mutations in one or more genes, 16/80 patients (20.0%) had no mutations. Mutations in CFTR were detected in 32/80 patients (40.0%) and 22 of them exhibited at least one mutation in genes of other pancreatic pathways. Of the remaining 48 patients, 13/80 (16.3%) had mutations in genes involved in premature activation of trypsinogen and 19/80 (23.8%) had mutations only in genes of the other pathways: 38/64 patients positive for mutations showed variants in two or more genes (59.3%). Conclusions: Our data, although to be extended with functional analysis of novel mutations, suggest a high rate of genetic heterogeneity in chronic pancreatitis and that trans-heterozygosity may predispose to the idiopathic CP phenotype.

Advantages of a next generation sequencing targeted approach for the molecular diagnosis of retinoblastoma.

BACKGROUND: Retinoblastoma (RB) is the most common malignant childhood tumor of the eye and results from inactivation of both alleles of the RB1 gene. Nowadays RB genetic diagnosis requires classical chromosome investigations, Multiplex Ligation-dependent Probe Amplification analysis (MLPA) and Sanger sequencing. Nevertheless, these techniques show some limitations. We report our experience on a cohort of RB patients using a combined approach of Next-Generation Sequencing (NGS) and RB1 custom array-Comparative Genomic Hybridization (aCGH). METHODS: A total of 65 patients with retinoblastoma were studied: 29 cases of bilateral RB and 36 cases of unilateral RB. All patients were previously tested with conventional cytogenetics and MLPA techniques. Fifty-three samples were then analysed using NGS. Eleven cases were analysed by RB1 custom aCGH. One last case was studied only by classic cytogenetics. Finally, it has been tested, in a lab sensitivity assay, the capability of NGS to detect artificial mosaicism series in previously recognized samples prepared at 3 different mosaicism frequencies: 10, 5, 1 %. RESULTS: Of the 29 cases of bilateral RB, 28 resulted positive (96.5 %) to the genetic investigation: 22 point mutations and 6 genomic rearrangements (four intragenic and two macrodeletion). A novel germline intragenic duplication, from exon18 to exon 23, was identified in a proband with bilateral RB. Of the 36 available cases of unilateral RB, 8 patients resulted positive (22 %) to the genetic investigation: 3 patients showed point mutations while 5 carried large deletion. Finally, we successfully validated, in a lab sensitivity assay, the capability of NGS to accurately measure level of artificial mosaicism down to 1 %. CONCLUSIONS: NGS and RB1-custom aCGH have demonstrated to be an effective combined approach in order to optimize the overall diagnostic procedures of RB. Custom aCGH is able to accurately detect genomic rearrangements allowing the characterization of their extension. NGS is extremely accurate in detecting single nucleotide variants, relatively simple to perform, cost savings and efficient and has confirmed a high sensitivity and accuracy in identifying low levels of artificial mosaicisms.

Hypoplastic left heart syndrome and 21q22.3 deletion.

Hypoplastic left heart syndrome (HLHS) is a rare congenital heart defect (CHD), associated with extracardiac anomalies in the 15-28% of cases, in the setting of chromosomal anomalies, mendelian disorders, and organ defects. We report on a syndromic female newborn with HLHS and terminal 21q22.3 deletion (del 21q22.3), investigated by Fluorescence In Situ Hybridization (FISH) using a panel of 26 contiguous BAC probes. Although rare, del 21q22.3 has been described in two additional patients with HLHS. In order to investigate the frequency and role of this chromosomal imbalance in the pathogenesis of left-sided obstructive heart defects, we screened for del 21q22.3 a series of syndromic and non-syndromic children with HLHS, aortic coarctation and valvular aortic stenosis, consecutively admitted to our hospital in a three-year period. Although none of the 56 analyzed patients were hemizygous for this region, the present case report and published patients argue that del 21q22 should be added to the list of chromosomal imbalances associated with HLHS. Accordingly, the presence of a cardiac locus mapping in the critical region cannot be excluded.

Epilepsy in patients with duplications of chromosome 14 harboring FOXG1.

BACKGROUND: Dup(14q12) harboring FOXG1 has been recently reported in individuals with developmental delay of variable severity, delayed/absent speech, and epilepsy/infantile spasms. FOXG1 was described as a dosage-sensitive gene encoding G1, a forkhead protein that is a brain-specific transcription factor with a role in brain development. PATIENTS: We extensively reviewed all published cases with dup(14) harboring FOXG1 and highlighted those epileptological features that are more commonly found among such cases. We also describe one new patient, detailing his peculiar clinical and neurophysiological findings. RESULTS: To date, 15 patients with dup(14) including FOXG1 have been reported; within those patients, nine also presented with epilepsy. At onset, the more frequent seizure type in the report and also in our patient is the epileptic spasm. Focal seizures might also be present. Outcomes in patients with epilepsy associated with dup(14) should be considered separately regarding seizures and cognitive and motor development. In the majority of patients (seven of 10, including ours), seizures tend to disappear and motor skills improve; however, instead stagnation of cognitive development is evident in all of them, associated with severe speech difficulties. CONCLUSIONS: There are some common features that should be considered: seizures with onset during the first year of life, particularly clusters of spasms and focal seizures with hypsarrhythmic electroencephalograph pattern; different degrees of cognitive impairment possibly associated with behavior disturbances and severe speech disabilities; and dysmorphic features in the absence of significant microcephaly.

Telomere shortening and telomere position effect in mild ring 17 syndrome.

BACKGROUND: Ring chromosome 17 syndrome is a rare disease that arises from the breakage and reunion of the short and long arms of chromosome 17. Usually this abnormality results in deletion of genetic material, which explains the clinical features of the syndrome. Moreover, similar phenotypic features have been observed in cases with complete or partial loss of the telomeric repeats and conservation of the euchromatic regions. We studied two different cases of ring 17 syndrome, firstly, to clarify, by analyzing gene expression analysis using real-time qPCR, the role of the telomere absence in relationship with the clinical symptoms, and secondly, to look for a new model of the mechanism of ring chromosome transmission in a rare case of familial mosaicism, through cytomolecular and quantitative fluorescence in-situ hybridization (Q-FISH) investigations. RESULTS: The results for the first case showed that the expression levels of genes selected, which were located close to the p and q ends of chromosome 17, were significantly downregulated in comparison with controls. Moreover, for the second case, we demonstrated that the telomeres were conserved, but were significantly shorter than those of age-matched controls; data from segregation analysis showed that the ring chromosome was transmitted only to the affected subjects of the family. CONCLUSIONS: Subtelomeric gene regulation is responsible for the phenotypic aspects of ring 17 syndrome; telomere shortening influences the phenotypic spectrum of this disease and strongly contributes to the familial transmission of the mosaic ring. Together, these results provide new insights into the genotype-phenotype relationships in mild ring 17 syndrome.

Array-CGH characterization and genotype-phenotype analysis in a patient with a ring chromosome 6.

BACKGROUND: Ring chromosome 6 is a rare constitutional abnormality that generally occurs de novo. The related phenotype may be highly variable ranging from an almost normal phenotype to severe malformations and mental retardation. These features are mainly present when genetic material at the end of the chromosome is lost. The severity of the phenotype seems to be related to the size of the deletion. About 25 cases have been described to date, but the vast majority reports only conventional cytogenetic investigations. CASE PRESENTATION: Here we present an accurate cyto-molecular characterization of a ring chromosome 6 in a 16-months-old Caucasian girl with mild motor developmental delay, cardiac defect, and facial anomalies. The cytogenetic investigations showed a karyotype 46,XX,r(6)(p25q27) and FISH analysis revealed the absence of the signals on both arms of the chromosome 6. These results were confirmed by means of array-CGH showing terminal deletions on 6p25.3 (1.3 Mb) and 6q26.27 (6.7 Mb). Our data were compared to current literature. CONCLUSIONS: Our report describes the case of a patient with a ring chromosome 6 abnormality completely characterized by array CGH which provided additional information for genotype-phenotype studies.