Here, we report a novel truncating mutation in the ubiquitin-specific peptidase gene (USP53) causing low-γ-GT (GGT) cholestasis. Genetic testing was carried out, including clinical exome sequencing for the proband and Sanger sequencing for the proband and his parents. The proband harbored a novel c.1017_1057del (p.(Cys339TrpfsTer7)) mutation in the ubiquitin carboxyl-terminal hydrolase (UCH) domain of USP53; we describe the clinical and laboratory features of the patient with a rare type of low-GGT cholestasis caused by this variant. The clinical presentation was found to be similar to that of phenotypes described in previous studies. However, there was an unusual presence of liver hemangiomas observed in our patient. Thus, our report reinforces the link between USP53 mutations and cholestasis. With this report, we confirm USP53 as the gene for low-GGT cholestasis and describe liver hemangiomas as a possible additional symptom of the phenotype spectrum. The inclusion of USP53 in the OMIM database and liver gene panels can further increase the effectiveness of molecular genetic studies.

Congenital and early onset bilateral sensorineural hearing loss (SNHL) is mainly caused by mutations in numerous genes. The introduction of universal newborn hearing screening (UNHS) has increased the number of infants with mild, moderate, and moderate-to-severe sensorineural hearing loss (SNHL) detected in the first year of life. We aimed to evaluate the audiological features in patients with mild, moderate, and moderate-to-severe SNHL according to genotype. Audiological and genetic data were analyzed for 251 patients and their relatives with congenital bilateral mild, moderate, and moderate-to-severe SNHL. Hearing loss severity, audiogram profile, interaural symmetry, and dynamics of hearing thresholds were analyzed. In this case, 165 patients had GJB2 gene mutations, 30 patients were identified with STRC mutations, and 16 patients had pathogenic or likely pathogenic USH2A mutations. The presence of at least one GJB2 non-truncating variant in genotype led to less severe hearing impairment. The flat and gently sloping audiogram profiles were mostly revealed in all groups. The follow-up revealed the stability of hearing thresholds. GJB2, STRC, and USH2A pathogenic variants were detected in most patients in our cohort and were congenital in most cases.

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GNE myopathy (GNEM) is a rare hereditary disease, but at the same time, it is the most common distal myopathy in several countries due to a founder effect of some pathogenic variants in the GNE gene. We collected the largest cohort of patients with GNEM from Russia and analyzed their mutational spectrum and clinical data. In our cohort, 10 novel variants were found, including 2 frameshift variants and 2 large deletions. One novel missense variant c.169_170delGCinsTT (p.(Ala57Phe)) was detected in 4 families in a homozygous state and in 3 unrelated patients in a compound heterozygous state. It was the second most frequent variant in our cohort. All families with this novel frequent variant were non-consanguineous and originated from the 3 neighboring areas in the European part of Russia. The clinical picture of the patients carrying this novel variant was typical, but the severity of clinical manifestation differed significantly. In our study, we reported two atypical cases expanding the phenotypic spectrum of GNEM. One female patient had severe quadriceps atrophy, hand joint contractures, keloid scars, and non-classical pattern on leg muscle magnetic resonance imaging, which was more similar to atypical collagenopathy rather than GNEM. Another patient initially had been observed with spinal muscular atrophy due to asymmetric atrophy of hand muscles and results of electromyography. The peculiar pattern of muscle involvement on magnetic resonance imaging consisted of pronounced changes in the posterior thigh muscle group with relatively spared muscles of the lower legs, apart from the soleus muscles. Different variants in the GNE gene were found in both atypical cases. Thus, our data expand the mutational and clinical spectrum of GNEM.

Juvenile amyotrophic lateral sclerosis (ALS) presents a group of few rare monogenic disorders with onset from early childhood up to 25 years and much more benign course than “classic” ALS. Autosomal dominant ALS type 4 (ALS4) related to SETX gene is one of them. In spite of characteristic combined involvement of central and peripheral motor neurons, ALS4 clinical diagnostics may be difficult, particularly in atypical and/or non‑familial cases and electroneuromyography underestimation. Massive parallel sequencing permits diagnosing majority of cases and performing genetic counselling in families.Aim of this work: to describe non‑familial ALS4 case detected by whole‑exome sequencing and present a review on poorly known disorder.A 21‑year‑old female patient in a consanguineous family was examined; methods: clinical, genealogical, electroneuromyography, peripheral nerves ultrasound; molecular: panel and whole‑exome sequencing, bioinformatical analysis.The girl is an only child and an only patient in a family of Mountain Jews – first cousins. She had spastic paraparesis since age of independent walking (1.5 y.o.) and early feet deformation, her first diagnosis was cerebral palsy. In 12 years spasticity progressed, walking was lost. After orthopedic surgery in 15 years supported walking restored, at that age leg distal amyotrophy developed with no further progressing. Due to electroneuromyography results polyneuropathy was misdiagnosed. In 21 years repeated electroneuromyography excluded polyneuropathy and detected generalized motor neuron impairment and juvenile ALS was suggested. On neurological examination pronounced spastic paraparesis together with peripheral leg paraparesis without sensory impairment were detected; her supported gait was of mixed spastic and paretic types; there were no fasciculations or fibrillations.Whole‑exome sequencing detected a novel heterozygous missense mutation c.4442A>G (p.Lys1481Arg) in SETX exon 10. Sanger familial sequencing was not possible, but DNA finding matching the phenotype supported ALS4 diagnosis. Juvenile ALS4 (SETX gene) is a relatively benign autosomal dominant disease, imitating in different stages other nervous disorders of early and young age; genealogy is not always informative. Along with typical cases (like our patient) clinical variability exists. Electroneuromyography is the main instrumental tool. Methods of massive parallel sequencing are optimal in DNA testing of juvenile ALS.