Molecular characterization of a 14q deletion in a boy with features of Holt-Oram syndrome

The Genetics of Canine Pulmonary Valve Stenosis

There have been recent advancements in understanding the genetic contribution to pulmonary valve stenosis (PS) in brachycephalic breeds such as the French Bulldog and Bulldog. The associated genes are transcriptions factors involved in cardiac development, which is comparable to the genes that cause PS in humans. However, validation studies and functional follow up is necessary before this information can be used for screening purposes.

Chromosome 14 deletions, rings, and epilepsy genes: A riddle wrapped in a mystery inside an enigma

The ring 14 syndrome is a rare condition caused by the rearrangement of one chromosome 14 into a ring-like structure. The formation of the ring requires two breakpoints and loss of material from the short and long arms of the chromosome. Like many other chromosome syndromes, it is characterized by multiple congenital anomalies and developmental delays. Typical of the condition are retinal anomalies and drug-resistant epilepsy. These latter manifestations are not found in individuals who are carriers of comparable 14q deletions without formation of a ring (linear deletions). To find an explanation for this apparent discrepancy and gain insight into the mechanisms leading to seizures, we reviewed and compared literature cases of both ring and linear deletion syndrome with respect to both their clinical manifestations and the role and function of potentially epileptogenic genes. Knowledge of the epilepsy-related genes in chromosome 14 is an important premise for the search of new and effective drugs to combat seizures. Current clinical and molecular evidence is not sufficient to explain the known discrepancies between ring and linear deletions.

Novel mutations of TCTN3/LTBP2 with cellular function changes in congenital heart disease associated with polydactyly

Congenital heart disease (CHD) associated with polydactyly involves various genes. We aimed to identify variations from genes related to complex CHD with polydactyly and to investigate the cellular functions related to the mutations. Blood was collected from a complex CHD case with polydactyly, and whole exome sequencing (WES) was performed. The CRISPR/Cas9 system was used to generate human pluripotent stem cell with mutations (hPSCs-Mut) that were differentiated into cardiomyocytes (hPSC-CMs-Mut) and analysed by transcriptomics on day 0, 9 and 13. Two heterozygous mutations, LTBP2 (c.2206G>A, p.Asp736Asn, RefSeq NM_000428.2) and TCTN3 (c.1268G>A, p.Gly423Glu, RefSeq NM_015631.5), were identified via WES but no TBX5 mutations were found. The stable cell lines of hPSCs-LTBP2^mu /TCTN3^mu were constructed and differentiated into hPSC-CMs-LTBP2^mu /TCTN3^mu . Compared to the wild type, LTBP2 mutation delayed the development of CMs. The TCTN3 mutation consistently presented lower rate and weaker force of the contraction of CMs. For gene expression pattern of persistent up-regulation, pathways in cardiac development and congenital heart disease were enriched in hPSCs-CM-LTBP2^mu , compared with hPSCs-CM-WT. Thus, the heterozygous mutations in TCTN3 and LTBP2 affect contractility (rate and force) of cardiac myocytes and may affect the development of the heart. These findings provide new insights into the pathogenesis of complex CHD with polydactyly.

Rare Case of Ulnar-Mammary-Like Syndrome With Left Ventricular Tachycardia and Lack of TBX3 Mutation

"Heart-hand" type syndromes represent a group of rare congenital conditions that combine cardiac pathology (structural defect or arrhythmic disorder) and limb abnormality. Significant clinical variability and genetic heterogeneity typical for such syndromes complicate correct diagnosis, prognosis, and appropriate genetic counseling of the affected families. By now, only single genes have been unambiguously determined as a genetic cause of heart-hand syndromes and phenotypically similar conditions. In the present study, we report on a 25-year-old Russian female patient with a clinical picture resembling ulnar-mammary syndrome (UMS). Principal clinical manifestations included heart septal fibrosis and non-sustained left ventricular tachycardia combined with fifth finger camptodactyly, hypoplastic breast, abnormal teeth, and mental retardation. Target Sanger sequencing and array-based comparative genome hybridization confirmed the lack of pathogenic mutations and large-scale deletions in TBX3 (12q24.21), the only gene known to be associated with UMS cases to date. Based on the results of whole-exome sequencing, 14 potential candidate variants were identified. Among them, a novel missense variant in SYNM gene (exon 1, c.173C > T, p.A58V), encoding intermediate filament protein synemin was characterized. Until the present, no association between SYNM mutations and congenital clinical syndromes has been reported. At the same time, taking into account synemin tissue-specific expression profiles and available data on abnormal knock-out mice phenotypes, we propose SYNM as a candidate gene contributing to the UMS-like phenotype. Further comprehensive functional studies are required to evaluate possible involvement of SYNM in genesis of complex heart-limb pathology.

"Minimal" holoprosencephaly in a 14q deletion syndrome patient

We report on a patient with terminal deletion of the long arm of chromosome 14 displaying brain interhemispheric fusion limited to the midline anterior frontal cortex associated with hypoplastic corpus callosum and incomplete rotation of the left hippocampus in a clinical setting of motor and intellectual disability with poor language, and social behavior abnormalities with aggressiveness. Some possible correlations between clinical signs and symptoms and various aspects of the complex brain malformation are briefly discussed and compared with other known abnormalities of chromosome 14. The different neuropathology of the most common forms and the new forms of holoprosencephaly recently described is also discussed and leads us to suggest classifying the interhemispheric fusion of this case as a "minimal" form of holoprosencephaly. This appears to be the first description in a 14q deletion patient.

Neurological features of 14q24-q32 interstitial deletion: report of a new case

Background

Interstitial deletions of the long arm of chromosome 14 involving the 14q24-q32 region have been reported in less than 20 patients. Previous studies mainly attempted to delineate recognizable facial dysmorphisms; conversely, descriptions on neurological features are limited to the presence of cognitive and motor delay, but no better characterization exists.

Case presentation

In this paper we report on a patient with a de novo interstitial deletion of 5.5 Mb at 14q24.3-q31.1. The deletion encompasses 84 genes, including fourteen Mendelian genes. He presented with dysmorphic face, developmental delay, paroxysmal non-epileptic events and, subsequently, epilepsy.

Conclusions

The clinical and molecular evaluation of this patient and the review of the literature expand the phenotype of 14q23-q32 deletion syndrome to include paroxysmal non-epileptic events and infantile-onset focal seizures.

Interstitial 14q24.3 to q31.3 deletion in a 6-year-old boy with a non-specific dysmorphic phenotype

BACKGROUND

Few patients with interstitial deletions in the distal long arm of chromosome 14 have been reported, and these patients showed rather indistinct features, including growth and mental retardation and phenotypic alterations.

RESULTS

We describe a de novo 14q interstitial deletion in a 6-year-old boy with dysmorphic facial traits such as hypertelorism, short and narrow palpebral fissures, broad nose with anteverted nostrils, long philtrum, thin upper lip with cupid's bow, prominent and everted lower lip, mildly low-set ears, as well as moderate developmental delay and mild mental retardation. Array-CGH mapped the deletion to the region 14q24.3 to 14q31.3, including 13.11 Mb, proximal to the imprinted genomic region of 14q32.

CONCLUSION

This mild phenotypic presentation suggests that the deleted segment does not contain essential genes for early organ development. Twenty-two genes with known functions, including Neurexin III (NRXN3, OMIM 600567), map to the region deleted in the propositus.

Deletions in 14q24.1q24.3 are associated with congenital heart defects, brachydactyly, and mild intellectual disability

Interstitial deletions of chromosome band 14q24.1q24.3 are apparently very rare. We report on three unrelated patients with overlapping de novo deletions of sizes 5.4, 2.8, and 2.3 Mb in this region. While some clinical problems such as intestinal malrotation, cryptorchidism, and ectopic kidney were only observed in single patients, all three patients had mild intellectual disability, congenital heart defects (truncus arteriosus, pulmonary atresia, atrial septal defect, and/or ventricular septal defect), brachydactyly, hypertelorism, broad nasal bridge, and thin upper lips. Likely haploinsufficiency of one or several of the 19 genes in the common deleted interval (ACTN1, DCAF5, EXD2, GALNTL1, ERH, SLC39A9, PLEKHD1, CCDC177, KIAA0247, LOC100289511, SRSF5, SLC10A1, SMOC1, SLC8A3, ADAM21P1, COX16, SYNJ2BP, SYNJ2BP-COX16, ADAM21) was responsible for these manifestations, but apart from SMOC1, mutations in which cause autosomal recessive Waardenburg anophthalmia syndrome, and ACTN1, mutations in which are associated with congenital macrothrombocytopenia, no disease associations have so far been reported for the other genes. Functional studies and a systematic search for mutations or chromosome aberrations in this region will elucidate the role of individual genes in the clinical manifestations and will provide insight into the underlying biological mechanisms.

Interstitial deletion of 14q24.3-q32.2 in a male patient with plagiocephaly, BPES features, developmental delay, and congenital heart defects

Distal interstitial deletions of chromosome 14 involving the 14q24-q23.2 region are rare, and only been reported so far in 20 patients. Ten of these patients were analyzed both clinically and genetically. Here we present a de novo interstitial deletion of chromosome 14q24.3-q32.2 in a male patient with developmental delay, language impairment, plagiocephaly, BPES features (blepharophimosis, ptosis, epicanthus), and congenital heart defect. The deletion breakpoints were fine mapped using fluorescence in situ hybridization (FISH) and the size of the deletion is estimated to be approximately 23 Mb. Based on genotype-phenotype comparisons of the 10 previously published patients and the present case, we suggest that the shortest regions for deletion overlap may include candidate genes for speech impairment, mental retardation, and hypotonia.