[Gerstmann-Sträussler disease: a familial case with common PRNP mutation and atypical features]

Gerstmann-Sträussler disease (GSD) is a very rare autosomal dominant late-onset neurodegenerative disorder related to prion protein gene PRNP. Mutation p.Pro102Leu produces about 80% of cases, which are often named GSD-102. DNA testing provides exact diagnosis. In the presented Russian family there were 3 patients: a female index case, age 32 years, her brother, age 37 years (age of onset in both is 27 years) and their deceased father (onset in 35 years, death in 44 years). GSD was not suspected until whole exome sequencing in the female detected PRNP mutation p.Pro102Leu confirmed in her and in the brother by Sanger sequencing. Atypical features of the case are: early onset in siblings, absence of mental and behavioral problems in the female and in the father and mild disturbances in the brother; epilepsy in the brother; atypical onset with transient signs in the brother. Other intrafamilial differences are prevailing spastic paraparesis in the female in contrast to predominant ataxia in the brother and dysarthria absence in the female. The case illustrates GSD-102 variability, complicating clinical diagnostics.

Osteogenesis Imperfecta: A Case Series and Literature Review

Osteogenesis imperfecta (OI) is a hereditary disease of connective tissue characterized by the loss of bone density and mass, which increases the fragility of the bones, thus presenting multiple fractures throughout the years followed by bone deformity and articular instability. This condition has various clinical presentations. We present four cases of OI, one case with type I, two cases with type II, and one case with type III. The clinical diagnosis in most of the cases was clinical; only one of them was confirmed with genomic sequence. The treatment of these cases was based on medication, orthopedic surgery, and recovery and physical therapy. The evolution was torpid in these cases but with prolonged life expectancy despite the severity and type of OI. It is important to highlight that the patients did not have a neurocognitive compromise. Early diagnosis and multidisciplinary medical management are crucial in obtaining better outcomes for this disease, improving the quality of life, and avoiding complications.

[AP4-assocated hereditary spastic paraplegias]

OBJECTIVE

In the course of studies of spastic paraplegias in Russian patients to detect AP4-associated forms, estimate their proportion in the total SPG group and analyze clinical and molecular characteristics.

MATERIAL AND METHODS

Five families of Russian ethnicity: four with SPG47, one with SPG51 (4 girls and a boy aged 2.5-9 years) were studied. Clinical and genealogical methods, whole-exome sequencing (WES) and verification by familial Sanger sequencing were used.

RESULTS

In our total group, including 118 families with 21 different forms, SPG AP4-associated forms accounted for 4.2% owing mainly to SPG47 (3.4%, 5^th place in SPG structure; 20% and 2^nd place in AE subgroup.) In non-consanguineous, unrelated SPG47 families three patients had identical genotypes: homozygosity for an earlier reported mutation c.1160_1161 delCA (p.Thr387ArgfsTer30) in AP4B1 exon 6; the 4^th patient was compound-heterozygous for the same mutation and novel c.1240C>T (p.Gln414Ter) in exon 7. Frequency of c.1160_1161 delCA may be caused by founder effect in Slavic populations though the idea needs additional studies. The SPG51 patient was compound heterozygous for novel AP4E1 mutations c.2604delA (p.Ser868fs) and c.3346A>G (p.Arg1116Gly). Parent's heterozygosity in all cases was confirmed by Sanger sequencing. Phenotypes were typical: early development delay, muscle hypotony transforming into sever spasticity, mental deficiency, microceplaly (in all SPG47 cases), epilepsy (in 3 SPG47 and SPG51 cases), MRI changes, mainly hydrocephalus and/or hypoplasia of corpus callosum (in 3 SPG47 cases) and few extraneural signs.

CONCLUSION

AP4-associated SPG should be taken into consideration in patients with early-onset severe nervous diseases mimicking non-genetic organic CNS disorders and massive exome sequencing (WES or other variants) should be performed.

[Ataxia with oculomotor apraxia type 4 detected by next-generation sequencing]

Ataxias with oculomotor apraxia (AOA) belong to autosomal recessive ataxias. Their common feature is oculomotor apraxia: inability to coordinate eye movements not due to muscle weakness. Next-generation sequencing (NGS) gives unique opportunities of rare disorders diagnostics and discovering of new forms, including AOA. In 2015, AOA type 4 produced by PNKP mutations was delineated in a group of Portuguese patients. We diagnosed AOA4 in a 9-year-old boy from Byelorussian family. He presented with ataxia since 2 years and deterioration in 8 years, oculomotor apraxia, dystonic hyperkinesia, dysarthria, polyneuropathy, borderline/mildly impaired intelligence, cerebellar atrophy on MRI and moderate hypercholesterolemia. Panel NGS detected two PNKP mutations: c.1123G>T (p.Gly375Trp) common in Portuguese patients, and novel c.1270_1283dupACAAACCCAGACGC (p.Ala429fs). This is one of a few world AOA4 cases and first non-Portuguese case with 'Portuguese' common mutation. The case illustrates NGS diagnostic value, particularly in rare heterogeneous disorders like AOA.

Lack of association between increased mitochondrial DNA4977 deletion and ATP levels of sputum cells from chronic obstructive pulmonary disease patients versus healthy smokers

In this study we looked at smokers with and without chronic obstructive pulmonary disease (COPD) patients in order to evaluate the incidence of 4977 base pair (bp) mtDNA (mtDNA⁴⁹⁷⁷) deletion and mtDNA copy number in sputum cells and in peripheral blood leukocytes (PBLs) in relation to mitochondrial function and oxidative stress status. Twenty-five COPD patients who were current smokers, 22 smokers and 23 healthy nonsmokers (for only PBLs studies) participated in this study. The 4977-bp deletion was detected in all examined samples within 40 cyles of PCR amplification, using a quantitative real time PCR. The frequency of the mtDNA⁴⁹⁷⁷ was significantly higher in the sputum cells of patients with COPD compared to smokers without COPD (p < 0.0001). This difference was not observed in PBLs. Levels of cellular oxidative stress were significantly higher in the sputum cells of subjects with COPD than in the smoker group. However, mtDNA copy number, mitochondrial membrane potential (ΔΨm) and cellular ATP levels in PBLs and sputum cells were not significantly different between the studied groups. The Pearson analysis revealed no correlations between the accumulation of mtDNA⁴⁹⁷⁷, and intracellular ATP content and ΔΨm values of the sputum cells, although there was a positive correlation between the increase in the percentage of deleted mtDNA⁴⁹⁷⁷ and the levels of cellular oxidative stress in COPD patients (r = 0.80, p < 0.0001). Our studies may suggest that the accumulation of mtDNA⁴⁹⁷⁷ in the sputum cells of smokers with COPD does not seem to have an important impact on mitochondrial dysfunction in relation to ATP production and ΔΨm when compared to those of healthy smokers.