Severe congenital contractural arachnodactyly caused by biallelic pathogenic variants in FBN2

Fibrillin-2, encoded by FBN2, plays an important role in the early process of elastic fiber assembly. To date, heterozygous pathogenic variants in FBN2 have been shown to cause congenital contractural arachnodactyly (CCA; Beals-Hecht syndrome). Classical CCA is characterized by long and slender fingers and toes, ear deformities, joint contractures at birth, clubfeet, muscular hypoplasia and often tall stature. In individuals with a severe CCA form, different cardiovascular or gastrointestinal anomalies have been described. Here, we report on a 15-year-old girl with a severe form of CCA and novel biallelic variants in FBN2. The girl inherited the missense variant c.3563G > T/p.(Gly1188Val) from her unaffected father and the nonsense variant c.6831C > A/p.(Cys2277*) from her healthy mother. We could detect only a small amount of FBN2 transcripts harboring the nonsense variant in leukocyte-derived mRNA from the patient and mother suggesting nonsense-mediated mRNA decay. As the father did not show any clinical signs of CCA we hypothesize the missense variant c.3563G > T to be a hypomorphic allele. Taken together, our data suggests that severe CCA can be inherited in an autosomal-recessive manner by compound heterozygosity of a hypomorphic and a null allele of the FBN2 gene.

Next-generation sequencing of 32 genes associated with hereditary aortopathies and related disorders of connective tissue in a cohort of 199 patients

PURPOSE

Heritable factors play an important etiologic role in connective tissue disorders (CTD) with vascular involvement, and a genetic diagnosis is getting increasingly important for gene-tailored, personalized patient management.

METHODS

We analyzed 32 disease-associated genes by using targeted next-generation sequencing and exome sequencing in a clinically relevant cohort of 199 individuals. We classified and refined sequence variants according to their likelihood for pathogenicity.

RESULTS

We identified 1 pathogenic variant (PV; in FBN1 or SMAD3) in 15 patients (7.5%) and ≥1 likely pathogenic variant (LPV; in COL3A1, FBN1, FBN2, LOX, MYH11, SMAD3, TGFBR1, or TGFBR2) in 19 individuals (9.6%), together resulting in 17.1% diagnostic yield. Thirteen PV/LPV were novel. Of PV/LPV-negative patients 47 (23.6%) showed ≥1 variant of uncertain significance (VUS). Twenty-five patients had concomitant variants. In-depth evaluation of reported/calculated variant classes resulted in reclassification of 19.8% of variants.

CONCLUSION

Variant classification and refinement are essential for shaping mutational spectra of disease genes, thereby improving clinical sensitivity. Obligate stringent multigene analysis is a powerful tool for identifying genetic causes of clinically related CTDs. Nonetheless, the relatively high rate of PV/LPV/VUS-negative patients underscores the existence of yet unknown disease loci and/or oligogenic/polygenic inheritance.

Control of the IR-spectral shift via modification of the surface relief between the liquid crystal matrixes doped with the lanthanide nanoparticles and the solid substrate

The influence of the surface nanostructured relief on the near IR-spectral shift and on the structural properties of the nematic liquid crystal (NLC) materials doped with nanoparticles from lanthanide group has been considered. The relief mentioned above has been made on the interface between glass substrate with ITO-coatings and the LC mesophase. The specific feature of this relief is based on the applying of the contactless laser deposition technique and on the its modification by using surface electromagnetic waves (SEW) or carbon nanotubes (CNTs) treated with SEW. The modified relief permits to orient LC molecules without direct polymer orienting layers and can be used as conducting layer too. The features mentioned above lead to decrease drastically the resistivity and the bias voltage as well as that permits to increase the transparency and reveal the near IR-shift in the spectral characteristics of the lanthanide-doped LC mesophase.

Lasing in DNA–CTMA doped with Rhodamine 610 in butanol

The lasing effect in a DNA–CTMA complex doped with Rh610 in butanol has been experimentally demonstrated.

Clinical spectrum of females with HCCS mutation: from no clinical signs to a neonatal lethal form of the microphthalmia with linear skin defects (MLS) syndrome

BACKGROUND

Segmental Xp22.2 monosomy or a heterozygous HCCS mutation is associated with the microphthalmia with linear skin defects (MLS) or MIDAS (microphthalmia, dermal aplasia, and sclerocornea) syndrome, an X-linked disorder with male lethality. HCCS encodes the holocytochrome c-type synthase involved in mitochondrial oxidative phosphorylation (OXPHOS) and programmed cell death.

METHODS

We characterized the X-chromosomal abnormality encompassing HCCS or an intragenic mutation in this gene in six new female patients with an MLS phenotype by cytogenetic analysis, fluorescence in situ hybridization, sequencing, and quantitative real-time PCR. The X chromosome inactivation (XCI) pattern was determined and clinical data of the patients were reviewed.

RESULTS

Two terminal Xp deletions of ≥ 11.2 Mb, two submicroscopic copy number losses, one of ~850 kb and one of ≥ 3 Mb, all covering HCCS, 1 nonsense, and one mosaic 2-bp deletion in HCCS are reported. All females had a completely (>98:2) or slightly skewed (82:18) XCI pattern. The most consistent clinical features were microphthalmia/anophthalmia and sclerocornea/corneal opacity in all patients and congenital linear skin defects in 4/6. Additional manifestations included various ocular anomalies, cardiac defects, brain imaging abnormalities, microcephaly, postnatal growth retardation, and facial dysmorphism. However, no obvious clinical sign was observed in three female carriers who were relatives of one patient.

CONCLUSION

Our findings showed a wide phenotypic spectrum ranging from asymptomatic females with an HCCS mutation to patients with a neonatal lethal MLS form. Somatic mosaicism and the different ability of embryonic cells to cope with an OXPHOS defect and/or enhanced cell death upon HCCS deficiency likely underlie the great variability in phenotypes.

Duchenne muscular dystrophy in a 4-year-old girl due to heterozygous frame shift deletion of the dystrophin gene and skewed X-inactivation

X-linked recessive diseases affect males, whereas female carriers are generally asymptomatic.We report on a 4-year-old girl who presented with a classical phenotype of Duchenne Muscular Dystrophy (DMD), a severe X-linked recessive type of muscular dystrophy affecting boys in early childhood.A thorough diagnostic work-up revealed that this resulted from a heterozygous out-of frame deletion in the DMD-gene in combination with an X-inactivation ratio of <10:90 in blood leukocytes and muscle.The case exemplifies that a skewed X-inactivation pattern has to be taken into account as mechanism causing clinical symptoms in female carriers of X-linked recessive disorders.

Phenotypic spectrum associated with CASK loss-of-function mutations

BACKGROUND

Heterozygous mutations in the CASK gene in Xp11.4 have been shown to be associated with a distinct brain malformation phenotype in females, including disproportionate pontine and cerebellar hypoplasia.

METHODS

The study characterised the CASK alteration in 20 new female patients by molecular karyotyping, fluorescence in situ hybridisation, sequencing, reverse transcriptase (RT) and/or quantitative real-time PCR. Clinical and brain imaging data of a total of 25 patients were reviewed.

RESULTS

11 submicroscopic copy number alterations, including nine deletions of ~11 kb to 4.5 Mb and two duplications, all covering (part of) CASK, four splice, four nonsense, and one 1 bp deletion are reported. These heterozygous CASK mutations most likely lead to a null allele. Brain imaging consistently showed diffuse brainstem and cerebellar hypoplasia with a dilated fourth ventricle, but of remarkably varying degrees. Analysis of 20 patients in this study, and five previously reported patients, revealed a core clinical phenotype comprising severe developmental delay/intellectual disability, severe postnatal microcephaly, often associated with growth retardation, (axial) hypotonia with or without hypertonia of extremities, optic nerve hypoplasia, and/or other eye abnormalities. A recognisable facial phenotype emerged, including prominent and broad nasal bridge and tip, small or short nose, long philtrum, small chin, and/or large ears.

CONCLUSIONS

These findings define the phenotypic spectrum associated with CASK loss-of-function mutations. The combination of developmental and brain imaging features together with mild facial dysmorphism is highly suggestive of this disorder and should prompt subsequent testing of the CASK gene.

Nonsense mutations in SMPX, encoding a protein responsive to physical force, result in X-chromosomal hearing loss

The fact that hereditary hearing loss is the most common sensory disorder in humans is reflected by, among other things, an extraordinary allelic and nonallelic genetic heterogeneity. X-chromosomal hearing impairment represents only a minor fraction of all cases. In a study of a Spanish family the locus for one of the X-chromosomal forms was assigned to Xp22 (DFNX4). We mapped the disease locus in the same chromosomal region in a large German pedigree with X-chromosomal nonsyndromic hearing impairment by using genome-wide linkage analysis. Males presented with postlingual hearing loss and onset at ages 3-7, whereas onset in female carriers was in the second to third decades. Targeted DNA capture with high-throughput sequencing detected a nonsense mutation in the small muscle protein, X-linked (SMPX) of affected individuals. We identified another nonsense mutation in SMPX in patients from the Spanish family who were previously analyzed to map DFNX4. SMPX encodes an 88 amino acid, cytoskeleton-associated protein that is responsive to mechanical stress. The presence of Smpx in hair cells and supporting cells of the murine cochlea indicates its role in the inner ear. The nonsense mutations detected in the two families suggest a loss-of-function mechanism underlying this form of hearing impairment. Results obtained after heterologous overexpression of SMPX proteins were compatible with this assumption. Because responsivity to physical force is a characteristic feature of the protein, we propose that long-term maintenance of mechanically stressed inner-ear cells critically depends on SMPX function.

Nonsense mutations in FAM161A cause RP28-associated recessive retinitis pigmentosa

Retinitis pigmentosa (RP) is a degenerative disease of the retina leading to progressive loss of vision and, in many instances, to legal blindness at the end stage. The RP28 locus was assigned in 1999 to the short arm of chromosome 2 by homozygosity mapping in a large Indian family segregating autosomal-recessive RP (arRP). Following a combined approach of chromatin immunoprecipitation and parallel sequencing of genomic DNA, we identified a gene, FAM161A, which was shown to carry a homozygous nonsense mutation (p.Arg229X) in patients from the original RP28 pedigree. Another homozygous FAM161A stop mutation (p.Arg437X) was detected in three subjects from a cohort of 118 apparently unrelated German RP patients. Age at disease onset in these patients was in the second to third decade, with severe visual handicap in the fifth decade and legal blindness in the sixth to seventh decades. FAM161A is a phylogenetically conserved gene, expressed in the retina at relatively high levels and encoding a putative 76 kDa protein of unknown function. In the mouse retina, Fam161a mRNA is developmentally regulated and controlled by the transcription factor Crx, as demonstrated by chromatin immunoprecipitation and organotypic reporter assays on explanted retinas. Fam161a protein localizes to photoreceptor cells during development, and in adult animals it is present in the inner segment as well as the outer plexiform layer of the retina, the synaptic interface between photoreceptors and their efferent neurons. Taken together, our data indicate that null mutations in FAM161A are responsible for the RP28-associated arRP.

Second-harmonic generation in poled polymers: pre-poling history paradigm

Experimental studies of second harmonic generation (SHG) from electric-field poled PMMA - DR1 system show occurrence of a maximum in diagonal and off diagonal tensor components χ(2)(-2ω;ω,ω) at 15 mol % concentration and a rapid decrease above, with a stabilization. The origin of the observed concentration dependence is studied using the Monte Carlo (MC) modeling. We find that presence of maximum is conditioned by the pre-poling history of the sample, when entanglement of linear dipolar structures takes place. Length of the pre-poling interval is an important kinetic parameter which differentiates between various nonexponential kinetics of build-up of polar phase responsible for strong/weak SHG susceptibility.

[Effects of dequalinium chloride and sanguinarine on the ultrastructure of early supragingival plaque]

The influence of antimicrobial mouthrinses containing dequalinium chloride or sanguinarine on early plaque formation was assessed in vivo in a clinical-experimental study. Rinses with water served as controls. After 24 and 72 hours, plastic films, which were applied to the buccal surfaces of six upper front teeth at the start of experiment, were removed and processed for transmission electron microscopic study. Dequalinium chloride or sanguinarine applied on plaque resulted in an increased and higher structured surface coating. Degenerated microorganisms were observed and the variety of bacteria seemed to be reduced. Both mouthrinses effected the early supragingival plaque formation. The effect of sanguinarine was more intensive than that of dequalinium chloride.