Transthyretin-related familial amyloid polyneuropathy (ATTR-FAP) in Poland - genetic and clinical presentation.

BACKGROUND: Transthyretin-related familial amyloid polyneuropathy (ATTR-FAP) is a rare, progressive, hereditary, highly disabling multisystem disorder. ATTR-FAP phenotypes differ according to the type of TTR mutation, geographic region and other as yet unidentified factors. The aim of this study was to establish the clinical and genetic characteristics of Polish patients. METHODS AND PATIENTS: Clinical data and necessary examinations were collected from patients diagnosed with ATTR-FAP at the Department of Neurology of Medical University of Warsaw between 1970 and 2019. RESULTS: 16 patients from eight unrelated families with five different TTR mutations were identified. The family with Val71Ala TTR mutation presented with early onset severe progressive polyneuropathy, with marked visual symptoms in a few patients. The next family with Ile73Val TTR mutation developed symptoms in middle age, and presented with mixed neuropathic and cardiologic phenotype. Four unrelated families were found to have the Phe33Leu TTR mutation with mixed neuropathic and cardiologic phenotype and late onset of symptoms. Other TTR mutations identified were: Val30Met and Asp38Val, both with late onset sensory, motor and autonomic neuropathy. CONCLUSION: Polish ATTR-FAP cases presented with heterogeneity typical for non-endemic areas. Phe33Leu TTR mutation was the most common, found in four unrelated families.

Charcot-Marie-Tooth type 1C disease coexisting with progressive multiple sclerosis: a study of an overlapping syndrome.

Charcot-Marie-Tooth type 1C disease (CMT1C) is a rare form of hereditary demyelinating neuropathy caused by mutations in the LITAF (lipopolysaccharide-induced tumor necrosis factor-) gene. CMT1C disease was mapped to chromosome 16p12-p 13.3. To date only a few mutations in the LITAF gene have been reported. Due to a small group of CMT1C reported patients, the phenotype of CMT1C is poorly characterized. CMT1C disease is a pure demyelinating neuropathy limited to the peripheral nervous system with a mild clinical course, manifesting without any additional symptoms. To the best of our knowledge, in this study, for the first time we present a three generational CMT1C family in which in the proband, CMT1C disease coexists with central demyelination fulfilling criteria of primary progressive multiple sclerosis (PPMS). The coexistence of PPMS and CMT1C in one family may not result from a common pathogenetic trait, however only in the proband with central demyelination and CMT1C we have detected a -308G>A sequence variant in the promoter of the TNF-α gene.

A new missense GDAP1 mutation disturbing targeting to the mitochondrial membrane causes a severe form of AR-CMT2C disease.

Charcot-Marie-Tooth disease (CMT) caused by mutations in the ganglioside-induced differentiation-associated protein 1 (GDAP1) gene is characterized by a spectrum of phenotypes. Recurrent nonsense mutations (Q163X and S194X) showing regional distribution segregate with an early onset, severe course of recessive CMT disease with early loss of ambulancy. Missense mutations in GDAP1 have been reported in sporadic CMT cases with variable course of disease, among them the recurrent L239F missense GDAP1 mutation occurring in the European population. Finally, some GDAP1 mutations are associated with a mild form of CMT inherited as an autosomal dominant trait. In this study, we characterize the CMT phenotype in one Polish family with recessive trait of inheritance at the clinical, electrophysiological, morphological, cellular, and genetic level associated with a new Gly327Asp mutation in the GDAP1 gene. In spite of the nature of Gly327Asp mutation (missense), the CMT phenotype associated with this variant may be characterized as an early onset, severe axonal neuropathy, with severe skeletal deformities. The mutation lies within the transmembrane domain of GDAP1 and interferes with the mitochondrial targeting of the protein, similar to the loss of the domain in the previously reported Q163X and S194X mutations. We conclude that the loss of mitochondrial targeting is associated with a severe course of disease. Our study shows that clinical outcome of CMT disease caused by mutations in the GDAP1 gene cannot be predicted solely on the basis of genetic results (missense/nonsense mutations).

Dysmyelinating and demyelinating Charcot-Marie-Tooth disease associated with two myelin protein zero gene mutations.

Mutations in the myelin protein zero (MPZ) gene are the third most frequent cause of hereditary motor and sensory neuropathies (HMSN), also called Charcot-Marie-Tooth disorders (CMT). Only in case of recurrent mutations occurring in the MPZ gene is it possible to draw phenotype-genotype correlations essential for establishing the prognosis and outcomes of CMT1. We have surveyed a cohort of 67 Polish patients from CMT families with demyelinating neuropathy for mutations in the MPZ gene. In this study, we report two CMT families in which the Ile135Thr and Pro132Leu mutations have been identified for the MPZ gene. These MPZ gene mutations had not been identified hitherto in the Polish population. The Pro132Leu mutation segregates with a severe early-onset dysmyelinating-hypomyelinating neuropathy, whereas the Ile135Thr substitution is associated with the classical phenotype of CMT1. To the best of our knowledge, we present here, for the first time, morphological data obtained in two sural nerve biopsies pointing to a hypomyelination-dysmyelination process in a family harboring the Pro132Leu mutation in the MPZ gene.

Familial partial lipodystrophy associated with the heterozygous LMNA mutation 1445G>A (Arg482Gln) in a Polish family.

Familial partial lipodystrophy (FPLD) belongs to the family of laminopathies - disorders associated with mutation in the lamin A/C gene (LMNA). FPLD is characterized by loss of subcutaneous adipose tissue from the limbs, trunk and buttocks, with its concomitant accumulation on the face, neck and intra-abdominal region, and by metabolic disorders. We present the first Polish family with FPLD confirmed genetically. A 34-year-old woman admitted with myalgia and cushingoid appearance was found to have a round face with double chin, neck bump, and loss of fat on extremities. Diagnostic tests revealed impaired glucose tolerance and increased levels of liver enzymes, and ultrasonography revealed hepatic steatosis. Her 9-year-old daughter presented a similar phenotype, but no fat loss. A genetic test revealed the presence of a heterozygous LMNA gene mutation: c.1445G>A, consistent with the "hot spot" for FPLD. Treatment with metformin to improve insulin resistance and address the diabetes proved successful.

A patient with both Charcot-Marie-Tooth disease (CMT 1A) and mild spinal muscular atrophy (SMA 3).

In the present study, we report a single Polish SMA family in which the 17p11.2-p12 duplication causative for the Charcot-Marie-Tooth type 1A disease (CMT1A) was found in addition to a deletion of exons 7 and 8 of the SMN1 gene. A patient harboring both SMA and CMT1A mutations manifested with SMA3 phenotype and foot deformity. Her electrophysiological testing showed chronic neurogenic changes in proximal muscles that are typical for SMA, but also slowed conduction velocity in motor and sensory fibers that is typical for demyelinating neuropathy.

Is a novel I214M substitution in the NEFL gene a cause of Charcot-Marie-Tooth disease? Functional analysis using cell culture models.

Recent studies have shown that mutations in neurofilament light subunit gene (NEFL) cause Charcot-Marie-Tooth (CMT) disease. Since the first description of the Gln333Pro mutation in the NEFL gene, 10 pathogenic mutations in the NEFL gene have been reported in patients affected with CMT disease. We report a novel I214M amino acid substitution in the NEFL gene in two unrelated patients affected with CMT. Because the I214M amino acid substitution in the NEFL protein was not detected in a CMT affected brother of the proband, its pathogenic effect became unclear. In order to determine whether this amino acid substitution is a benign polymorphism or causative of the disease, we performed a functional analysis of the mutant I214M neurofilament protein (NFL). Transfections of the mutant protein in cultured cells revealed an increased tendency to form highly compacted filamentous structures but no other alterations of neurofilament assembly or transport were observed. Furthermore, the sibling of one of the patients was also affected with CMT but did not have the I214M substitution. These data suggest that this I214M substitution in the NEFL gene was not a direct cause of the disease but could be a polymorphism or possibly a modifier of the CMT phenotype.

A novel Met116Thr mutation in the GDAP1 gene in a Polish family with the axonal recessive Charcot-Marie-Tooth type 4 disease.

Mutations in the gene coding for ganglioside-induced differentiation-associated protein-1 (GDAP1), which maps to chromosome 8q21, have been described in families with autosomal recessive Charcot-Marie-Tooth disease (CMT4A). Interestingly, some mutations in the GDAP1 gene have been reported in the demyelinating form of CMT1 disease, whereas others were found in patients with the axonal type of CMT disease. So far, 23 mutations in the GDAP1 gene have been reported in patients of different ethnic origins. In this study we report a novel mutation Met116Thr in the GDAP1 gene identified in a three generation Polish family with axonal CMT4.

Early onset Charcot-Marie-Tooth type 1B disease caused by a novel Leu190fs mutation in the myelin protein zero gene.

The spectrum of Charcot-Marie-Tooth (CMT) phenotypes segregating with mutations in the Myelin Protein Zero (MPZ) gene is wide and ranges from congenital hypomyelinating neuropathy (CHN) through demyelinating form of CMT to the axonal type of CMT disease. Within 94 MPZ gene mutations reported up to now, only a few were identified in the exon 4 of the MPZ gene. In this study we have identified a novel Leu190fs mutation in the MPZ gene. The Leu190fs mutation was found in a 14-year-old girl suffering from Charcot-Marie-Tooth type 1 disease (CMT1) with onset in early infancy. Similarly to the other MPZ gene frame-shift mutations reported as far the Leu190fs seems to have a dominant negative effect.

Phenomenon of Schwann cell apoptosis in a case of congenital hypomyelinating neuropathy with basal lamina onion bulb formation.

We analyzed a sural nerve biopsy of a child with congenital hypomyelinating neuropathy. A lack of normally myelinated fibres, abnormal architecture of premyelin fibres and basal lamina onion bulbs were identified. The most prominent pathological finding was the appearance of significant death of Schwann cells with apoptotic morphology. This new finding may suggest that abnormal premyelin fibres are susceptible to death and that their disappearance is responsible for empty basal lamina onion bulb formation.