Floppy infant syndrome as a first manifestation of LMNA-related congenital muscular dystrophy.

LMNA-related congenital muscular dystrophy (L-CMD) is the most severe phenotypic form of skeletal muscle laminopathies. This paper reports clinical presentation of the disease in 15 Polish patients from 13 families with genetically confirmed skeletal muscle laminopathy. In all these patients floppy infant syndrome was the first manifestation of the disease. The genetic diagnosis was established by next generation sequencing (targeted panel or exome; 11 patients) or classic Sanger sequencing (4 patients). In addition to known pathogenic LMNA variants: c.116A > G (p.Asn39Ser), c.745C > T (p.Arg249Trp), c.746G > A (p.Arg249Gln), c.1072G > A (p.Glu358Lys), c.1147G > A (p.Glu383Lys), c.1163G > C (p.Arg388Pro), c.1357C > T (p.Arg453Trp), c.1583C > G (p.Thr528Arg), we have identified three novel ones: c.121C > G (p.Arg41Gly), c.1127A > G (p.Tyr376Cys) and c.1160T > C (p.Leu387Pro). Eleven patients had de novo mutations, 4 - familial. In one family we observed intrafamilial variability of clinical course: severe L-CMD in the male proband, intermediate form in his sister and asymptomatic in their mother. One asymptomatic father had somatic mosaicism. L-CMD should be suspected in children with hypotonia in infancy and delayed motor development, who have poor head control, severe hyperlordosis and unstable and awkward gait. Serum creatine kinase may be high (~1000IU/l). Progression of muscle weakness is fast, leading to early immobilization. In some patients with L-CMD joint contractures can develop with time. MRI shows that the most frequently affected muscles are the serratus anterior, lumbar paraspinal, gluteus, vastus, adductor magnus, hamstrings, medial head of gastrocnemius and soleus. Ultra-rare laminopathies can be a relatively common cause of generalized hypotonia in children. Introduction of wide genome sequencing methods was a breakthrough in diagnostics of diseases with great clinical and genetic variability and allowed approach "from genotype do phenotype". However target sequencing of LMNA gene could be considered in selected patients with clinical picture suggestive for laminopathy.

A Rare Mutation in The APOB Gene Associated with Neurological Manifestations in Familial Hypobetalipoproteinemia.

Clinical phenotypes of familial hypobetalipoproteinemia (FHBL) are related to a number of defective apolipoprotein B (APOB) alleles. Fatty liver disease is a typical manifestation, but serious neurological symptoms can appear. In this study, genetic analysis of the APOB gene and ophthalmological diagnostics were performed for family members with FHBL. Five relatives with FHBL, including a proband who developed neurological disorders, were examined. A sequencing analysis of the whole coding region of the APOB gene, including flanking intronic regions, was performed using the next-generation sequencing (NGS) method. Electrophysiological ophthalmological examinations were also done. In the proband and his affected relatives, NGS identified the presence of the pathogenic, rare heterozygous splicing variant c.3696+1G>T. Two known heterozygous missense variants-c.2188G>A, p.(Val730Ile) and c.8353A>C, p.(Asn2785His)-in the APOB gene were also detected. In all patients, many ophthalmologic abnormalities in electrophysiological tests were also found. The identified splicing variant c.3696+1G>T can be associated with observed autosomal, dominant FHBL with coexisting neurological symptoms, and both identified missense variants could be excluded as the main cause of observed clinical signs, according to mutation databases and the literature. Electroretinography examination is a sensitive method for the detection of early neuropathy and should therefore be recommended for the care of patients with FHBL.

Identification and characterization of the first microsatellite loci for the thick-shelled river mussel Unio crassus (Bivalvia: Unionidae).

The thick-shelled river mussel Unio crassus is critically endangered throughout its range as a result of increasing human activity and habitat loss. Next generation DNA sequencing was used to develop a set of microsatellite markers that can be used for future ecological and population genetics studies of U. crassus. A total of 11 polymorphic loci were identified and characterized using 57 individuals from two Polish populations. Numbers of alleles ranged from 2 to 15 and expected heterozygosity levels ranged from 0.069 to 0.899. Deficiency of heterozygous genotypes was observed in four loci. Marker independence was confirmed with tests for linkage disequilibrium, however, analyses indicated evidence of null alleles in four loci. The microsatellite markers developed specifically for U. crassus provide a valuable tool for future ecological, population genetic assessments, and conservation management of this species.