Two different presentations of de novo variants of CSNK2B: two case reports

Background Poirier–Bienvenu neurodevelopmental syndrome is a neurologic disorder caused by mutations in the CSNK2B gene. It is mostly characterized by early-onset seizures, hypotonia, and mild dysmorphic features. Craniodigital syndrome is a recently described disorder also related to CSNK2B, with a single report in the literature. Objective To report two unrelated cases of children harboring CSNK2B variants (NM_001320.6) who presented with distinct diseases. Case report Case 1 is a 7-month-old, Caucasian, female patient with chief complaints of severe hypotonia and drug-refractory myoclonic epilepsy, with a likely pathogenic de novo variant c.494A>G (p.His165Arg). Case 2 is a 5-year-old male, Latino patient with craniodigital intellectual disability syndrome subjacent to a de novo, likely pathogenic variant c.94G>T (p.Asp32Tyr). His dysmorphic features included facial dysmorphisms, supernumerary nipples, and left-hand postaxial polydactyly. Conclusion This report suggest that the CSNK2B gene may be involved in the physiopathology of neurodevelopmental disorders and variable dysmorphic features.

A Novel Mutation Diagnosing in Allan–Herndon–Dudley's Syndrome

Allan–Herndon–Dudley's syndrome (AHDS) is a rare X-linked recessive disease that causes abnormal serum thyroid function tests, severe hypotonia, intellectual disability, and motor deficit due to a mutation in the monocarboxylate transporter 8, which is a thyroid hormone transporter. A 6-month-old male patient presented to our outpatient clinic with a serious hypotonia complaint. With a preliminary diagnosis of AHDS, a molecular genetic examination was performed. The molecular genetic analysis detected a new previously unidentified variant in the SLC16A2 gene. This case has been presented to report the AHDS, which is a rare cause of hypotonia in patients presenting/consulting with severe hypotonia, global developmental delay, and abnormal thyroid function test results. Besides, a novel pathogenic mutation in the SLC16A2 gene has been described in the present article.

Hepatobiliary disease in XLMTM: a common comorbidity with potential impact on treatment strategies

Background X-linked myotubular myopathy (XLMTM) is a rare congenital myopathy resulting from pathogenic variants in the MTM1 gene. Affected male subjects typically present with severe hypotonia and respiratory distress at birth and they often require intensive supportive care. Long-term survivors are often non-ambulant, ventilator and feeding tube–dependent and they generally show additional organ manifestations, indicating that myotubularin does play a vital role in tissues other than muscle. For XLMTM several therapeutic strategies are under investigation. For XLMTM several therapeutic strategies are under investigation including a study of intravenous MTM1 gene transfer using a recombinant AAV8 vector of which has some concerns arises due to hepatotoxicity. Results We report prospective and retrospective clinical data of 12 XLMTM patients collected over a period of up to 10 years. In particular, we carried out a thorough review of the data about incidence and the course of hepatobiliary disease in our case series. Conclusions We demonstrate that hepatobiliary disease represents a common comorbidity of XLMTM that seems irrespective to age and diseases severity. We recommend to carefully explore and monitor the hepatobiliary function in XLMTM patients. We believe that a better understanding of the pathogenic mechanisms that induce hepatobiliary damage is essential to understand the fatal events that may occur in the gene therapy program.

Hepatobiliary disease in XLMTM. A common comorbidity with potential impact on treatment strategies

BACKGROUND: X-linked myotubular myopathy (XLMTM) is a rare congenital myopathy resulting from pathogenic variants in the MTM1 gene. Affected male subjects typically present with severe hypotonia and respiratory distress at birth and they often require intensive supportive care. Long-term survivors are often non-ambulant, ventilator and feeding tube–dependent and they generally show additional organ manifestations, indicating that myotubularin does play a vital role in tissues other than muscle. For XLMTM several therapeutic strategies are under investigation.A recent clinical trial delivering the MTM1 gene using a recombinant AAV8 vector to XLMTM patients showed encouraging results in term of efficacy, but some concerns about safety arised due to three fatal events related to hepatotoxicity in boys that were exposed to the higher dose.RESULTS: We report prospective and retrospective clinical data of 12 XLMTM patients collected over a period of up to 10 years. In particular, we carried out a thorough review of the data about incidence and the course of hepatobiliary disease in our case series.CONCLUSIONS: We demonstrate that hepatobiliary disease represents a common comorbidity of XLMTM that seems irrespective to age and diseases severity. We recommend to carefully explore and monitor the hepatobiliary function in XLMTM patients. We believe that a better understanding of the pathogenic mechanisms that induce hepatobiliary damage is essential to understand the fatal events that may occur in the gene therapy program.

Novel Treatment for Congenital Disorder of Glycosylation in a Patient with Novel Homozygote Mutation of PMM2: A Case Report and Review Literature

Background: In Congenital Disorder of Glycosylation (CDG) type Ia, homozygous mutations of the PMM2 gene cause phosphomannomutase 2 dysfunction. Case presentation: Herein, a 10-month-old girl is presented with severe hypotonia along with inappropriately normal mental status and normal facies. High 2-ketoglutaric acid was detected in her urine; therefore the diagnosis of 2-Ketoglutarate dehydrogenase complex (KDHC) deficiency was made for this patient. High dose of vitamin B1 was administered, because thiamine is considered as a co-factor in this inborn error of metabolism. She responded very well to daily administration of 500 mg/day vitamin B1 and stood up without help 5 months later. She had experienced seizure, which responded well to pyridoxine. Now, she is a 3.5-years-old child, who could talk and walk normally. Recently, whole exome sequencing was performed for her, which showed homozygote mutation of PMM2; therefore the diagnosis was changed from KDHC deficiency to PMM2-CDG. Conclusion: Attention to the pathophysiology of inborn errors of metabolism is necessary, while considering the defective enzymes co-factor may help us to find an option for treatment of such rare diseases.

A Variant in SLC25A4 Leads to Mitochondrial DNA-Depletion Syndrome-12A Causing Neonatal Hypotonia and Hypoventilation

Congenital hypotonia and hypoventilation is a rare association. We report a rare case of a female newborn with poor respiratory drive, ventilator dependency, severe hypotonia, cardiomyopathy, and premature death. Clinical-exome-sequencing revealed SLC25A4-related mitochondrial deoxyribonucleic acid (DNA) depletion syndrome-12A (cardiomyopathic type). This syndrome is apparent at birth and carries a poor prognosis.

6q13q14.3 Microdeletion Syndrome with Severe Hypotonia and Facial Dysmorphism: Genotype–Phenotype Correlation

Hypotonia is a symptom of diminished tone of skeletal muscle and can be nongenetic or a part of genetic syndrome. Hypotonia, developmental delay, and facial dysmorphism are nonspecific findings observed in many genetic syndromes mostly in chromosomal microdeletion and duplication. Here we report a case with severe hypotonia and facial dysmorphism, diagnosed with deletion at 6q13q14.3 by array comparative genomic hybridization (CGH) at very early age. Recent genetic diagnostic technologies such as array CGH may enable clinicians to diagnose chromosomal abnormalities earlier and provide appropriate medical management

A deletion in CFL-2 gene associated with Severe Nemaline Myopathy with peculiar features

Context: Nemaline myopathy (NM) is the most common congenital myopathy characterized by muscle weakness and presence of nemaline bodies (rods) in muscle biopsy. Phenotype ranges from neonatal death to normal lifespan. 13 genes have been reported. We describe a new variant in cofilin 2 gene (CFL2;OMIM*601443). Case report: A 5-year-old boy born severely hypotonic and unable to breathe, in need of mechanic ventilation. Healthy non-consanguineous parents. Physical examination: severe hypotonia with only extraocular motricity preserved and multiple contractures. Dysmorphic features were observed as brachycephaly, hypertelorism, pseudohypertrophy, macroglossia, premature pubic hair. Deep reflexes were absent. CK: 1010U/l. DHEA-S elevated. Muscular biopsy: Rods, cores and dystrophic pattern. Exome: homozygous deletion in exons 1 to 4 of CFL2 and partial deletion of the next gene Sorting nexin-6 (SNX6) in Chr14:34.563.122-34.714.639. Conclusion: 9 cases were described previously: Age onset was before 31 months. 4 presented respiratory distress at birth, 1 presented macroglossia, 2 contractures, 2 spinal deformities and 3 delayed motor milestones. Our patient presents an extent deletion in homozygosis not described before. A second deletion was found in SNX6, which is involved in protein trafficking and is expressed in different cells, as endocrine and cardiac. The early puberty and dimorphisms could be due to SNX6, though there is no previous disease caused by this gene. Among differential diagnosis of macroglossia, congenital myopathy caused by CFL2 should be considered.

Two different missense mutations of PEX genes in two similar patients with severe Zellweger syndrome: an argument on the genotype-phenotype correlation

BackgroundPeroxisomal biogenesis disorders (PBDs) include a miscellaneous group of diseases which cause serious multisystem disease. Mutations of 13 different PEX genes lead to PBDs including Zellweger syndrome (ZS). Different types of mutations of PEX1 and PEX10 genes are correlated with broad-range phenotypes of PBDs.Case presentationPatient 1 is a 4-month-old boy who was affected by myoclonic seizures, poor oral feeding since birth. The patient was hypotonic and had hepatosplenomegaly. Patient 2 is a 2-month-old boy who presented with decreased movement, severe hypotonia and failure to thrive. The laboratory studies of the patients revealed increased plasma very-long-chain fatty acids (VLCFAs). The genetic analyses of patient 1 demonstrated the first homozygous missense mutation in the PEX10 gene. A novel homozygous missense mutation was found in the PEX1 gene in patient 2.ConclusionsThis report highlights that the detected homozygous missense mutations of PEX10 and PEX1 genes and the substitutions of specific amino acids lead to the severe form of PBDs.