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.

Clinical characteristics of rare CFTR mutations causing cystic fibrosis in Polish population.

INTRODUCTION: More than 2000 mutations have been identified since the discovery of the CFTR gene in 1989. However, only 346 mutations have been classified as cystic fibrosis (CF)-causing mutations. Due to the increasing number of mutations and poor correlation between the genotype and phenotype, there is an urgent need to determine the mutations that are pathogenic, nonpathogenic, or lead to variable symptoms. AIM: The aim of the study was to present the clinical characteristics of Polish patients with rare and novel CFTR mutations, with an attempt to determine the pathogenicity status of those variants. MATERIALS AND METHODS: The group included 13 patients born between September 2006 and May 2019, who underwent CF newborn screening and in whom two CFTR mutations, including at least one rare or a novel mutation, were identified. RESULTS: We identified 13 patients with mutations in both alleles of the CFTR gene, one of which was at least rare in Polish population (R289NfsX17, I618RfsX2, T682KfsX40, S1347PfsX13, W356X, E33X, dup.16,17A) or was a mutation of unknown clinical consequences (H199R, L468P, A1217E, Q359R, T1036I, W1282R). None of them were described in the CFTR2 database. In all examined patients, sweat tests were elevated. The diagnosed patients presented with a wide spectrum of clinical symptoms. Broad clinical characteristics and test results are presented. CONCLUSION: Pathogenic mutations are H199R, L468P, A1217E, Q359R, T1036I, W1282R, R289NfsX17, I618RfsX2, T682KfsX40, S1347PfsX13, W356X, E33X, dup.16,17A. Every patient with a mutation of unknown clinical consequences in one CFTR allele requires attentive follow-up.

Molecular analysis of mucopolysaccharidosis type VI in Poland, Belarus, Lithuania and Estonia.

Mucopolysaccharidosis VI (MPS VI) is a rare autosomal recessive disorder caused by a deficiency of N-acetylgalactosamine-4-sulfatase (ARSB). Over 130 ARSB gene mutations have been identified thus far and most mutations are unique to individual families. We aimed to analyze the spectrum of mutations in the ARSB gene responsible for the disorder in Poland, Belarus and Baltic States. Twenty one families with MPS VI patients, in whom diagnosis was confirmed biochemically and enzymatically, were studied. Direct sequencing of patient genomic DNA was used to identify ARSB mutations. In total, fourteen different disease-causing mutations were found. Three novel mutations included insertion c.375_376insT, a missense mutation c.499G>A (p.G167R) and deletion/insertion c.750_754delinsCCTGAAGTCAAG. We also report 11 previously described mutations (p.A33V, p.W57C, p.Q88X, p.T92K, p.Q97X, p.R152W, p.R160Q, p.R160X, p.Y210C, p.Y266S, p.G302R). The mutation p.R152W was present at a high prevalence of 50% (21/42) the mutated alleles in this group of patients. High prevalence of p.R152W mutation in Poland, Belarus and Baltic States indicates a possible founder effect and suggests that screening for this mutation may be appropriate in MPS VI patients from this region. Our study has also provided evidence to support genotype-phenotype correlation.