Molecular Genetics and Metabolism Reports最新文献

Social determinants of health (SDOH) are conditions in which people are born, grow, live, work, and age. Variations in these conditions are largely responsible for health inequities, the differences in health status or distribution of health resources within a population. Despite recent increases in attention to SDOH in research and clinical practice, few, if any, resources exist to describe how these complex dynamics impact patients with inborn errors of metabolism. Recognizing the role real-life narratives have as a powerful educational tool, we compiled a series of 3 original cases, published as part of this special supplement, to illustrate challenges and learnings related to SDOH within the context of urea cycle disorders and phenylketonuria.

A Black young adult female diagnosed with argininosuccinate lyase deficiency at 6 months of age encountered significant barriers to care for the first 16 years of her life due to socioeconomic factors and parental neglect. Once in the care of her paternal grandmother, she received appropriate treatment with a nitrogen scavenger, amino acid supplementation, and a low-protein diet. However, due to repeated hyperammonemic crises early in her life, she was minimally communicative and unable to perform activities of daily living. During her final hyperammonemic crisis, she presented to a hospital unfamiliar with urea cycle disorders and without a metabolic service. As a result, she did not receive optimal care and died.

Argininosuccinic aciduria (ASA) is a disorder that results from a deficiency in the urea cycle enzyme argininosuccinate lyase. Variable manifestations of this hereditary disorder are associated with hyperammonemia and can include lethargy, somnolence, and respiratory alkalosis in neonates, and vomiting, headaches, and neurocognitive deficiencies later in life. Management of ASA includes rapid measures to address hyperammonemia and long-term steps to maintain metabolic stability. Management paradigms should also consider social determinants of health, which are non-medical factors that influence health outcomes. Here, we describe the case of a male pediatric patient with ASA whose treatment has included considerations for his family's refugee status, language barriers, cultural adjustments, limited income, and transportation challenges.

AimHyperphosphatemic Familial Tumoral Calcinosis (HFTC) is an autosomal recessive disorder. This study investigates the etiology of HFTC in offspring from consanguineous parents.

Methods

Clinical assessment, imaging, and direct sequencing were utilized to elucidate the condition. Previously reported cases were also reviewed.

Result

We identified a consanguineous Chinese family with HFTC caused by an interesting homozygous G to A substitution in GALNT3 (c.1626 + 1G > A). The parents were carriers.

Conclusion

This study represents the first report of HFTC in a consanguineous Chinese family due to an interesting GALNT3 mutation. We reviewed known GALNT3 variants and associated clinical features of calcification disorders. The phenotypic difference between homozygous and complex heterozygous mutations is not clinically significant. Gene mutations affect the function of proteins mainly by affecting their binding to polyvalent ligands.

Niemann Pick Type C disease is a rare and progressive neurodegenerative lysosomal storage disorder caused by autosomal recessive mutations in the NPC1 and NPC2 genes. It is characterized by the accumulation of multiple lipid species in the endolysosomal compartment, leading to neurodegeneration and involvement of the liver, spleen, and lungs. Niemann Pick Type C has a wide range of presentations and severities at different ages with different progression rates. According to the Human Gene Mutation Database, to date, 486 disease-causing mutations in the highly polymorphic NPC1 gene and >20 mutations in the NPC2 have been reported. In the present study, we described the clinical, biochemical, and molecular profiles of 18 Iranian patients with Niemann-Pick Type C disease. Also, we describe six novel variants of the NPC1 gene, to our knowledge, not reported to date.

Aim

To analyze the clinical phenotype and genetic etiology of three cases of glutaric aciduria type 1 (GA1) in Chinese children.

Methods

We performed genetic and metabolic testing using tandem mass spectrometry (MS/MS) and gas chromatography–mass spectrometry (GC/MS), followed by trio whole-exome sequencing (trio-WES) and Sanger sequencing. A literature review on glutaric aciduria type 1 (GA1) in Chinese patients was also conducted.

Results

Sequencing results showed each case had compound heterozygous variants in GCDH(NM_000159.4): c.214C > G (p.Arg72Gly) and c.411C > G (p.Tyr137Term) (Case 1), c.214C > G (p.Arg72Gly) and c.1204C > T (p.Arg402Trp) (Case 2), and c.1228G > T (p.Val410Leu) and c.395G > A (p.Arg132Gln) (Case 3). These variants were inherited from their respective parents. Notably, the c.214C > G variant found in two children was a novel variant not previously reported. A review of the literature revealed that, clinically, the majority of patients experienced onset in infancy and early childhood (82%). Additionally, 38.36% were diagnosed through newborn screening, with the primary reasons for the initial visit being delayed development (32.43%) and infections (21.61%). The most common clinical manifestations included increased head circumference (77.19%) and motor developmental delay (65.15%). Biochemically, patients exhibited significant elevations in C5DC (98.51%) and C5DC/C8 (94.87%) in blood, as well as GA (94.37%) and 3OHGA (69.39%) in urine. Radiographically, patients showed a high prevalence of abnormalities in cranial MRI (86.15%) and EEG (73.33%). Genetically, 67 distinct GCDH gene variants were identified among 73 patients, with missense variants being the most prevalent type (73.97%). The most frequent variant was c.1244-2 A > C, observed in 17.12% of cases. Additionally, the majority of variant sites were located in exons 11 (25.37%) and 6 (22.39%).

Conclusion

GCDH variants were identified as the causative factors in the three children. The discovery of the novel variant (c.214C > G) expands the spectrum of pathogenic GCDH variants. These findings facilitate the diagnosis and treatment of affected children and provide a basis for genetic counseling and prenatal diagnosis for their families.

Introduction

Infantile-onset Pompe disease (IOPD) is due to mutations in the GAA gene leading to profound deficiency of the lysosomal enzyme α-1,4-glucosidase. The disease is characterized by severe hypotonia, hypertrophic cardiomyopathy, macroglossia, and liver enlargement with onset in the first months of life. In the late-onset form (LOPD), muscle signs predominate with a clinical picture resembling muscle dystrophies. Enzyme replacement therapy with alglucosidase alfa (rhGAA) has been available since 2006 and patients treated with the enzyme show improved outcomes. Nevertheless, there is evidence that some patients have a suboptimal response or, after an initial improvement, reach a plateau with stabilization of the clinical picture. Thus, a new enzyme formulation, avalglucosidase alfa (neoGAA), with a higher degree of mannosylation, was developed.

Methods

We conducted a multicenter survey that collected data on four patients with IOPD, aged 6 to 16 years, who were switched to neoGAA thanks to a compassionate use program, after being treated for an average of 11.5 years with rhGAA. Follow-up data, including biochemical parameters and clinical features, were analyzed to determine clinical outcomes and the safety profile after a mean of 9 months.

Results

Patients with IOPD who were treated with neoGAA showed a positive change in biomarker levels. Moreover, the clinical picture revealed improved motor performance and cardiac parameters in patients who previously responded poorly.

Conclusion

This study highlights the improved efficacy of neoGAA, as a next generation enzyme replacement therapy, in 4 Italian patients with IOPD. Several clinical parameters showed a positive response to the new formulation suggesting that, if used at diagnosis, neoGAA may result in better outcomes for patients with IOPD.

Schwartz-Jampel syndrome (SJS) is a rare autosomal recessive disorder characterized by muscle stiffness (myotonia) and chondrodysplasia. This disease is caused by biallelic loss of function mutations in the HSPG2 gene, which encodes the core protein of perlecan. This study aims to investigate causative variants in two sisters born to consanguineous Iranian parents. Both patients were presented with myotonia and a mask-like face; moreover, they showed a less common symptom, gastrointestinal bleeding, which is not typical of SJS and has only been reported in one patient. Regarding the crucial role of perlecan in vascular structure and mucosal stability, bleeding disorders could be expected in perlecan dysfunctions. In addition to the case study, a comprehensive literature review was conducted to gather information on similar genetic variants, associated clinical features, and possible disease mechanisms. Results of this study contribute to our understanding of the genetic and clinical aspects of Schwartz-Jampel syndrome, and more importantly, the manifestation of gastrointestinal bleeding in patients with Schwartz-Jampel syndrome.

Olipudase alfa is indicated for the non-central nervous system manifestations of Acid sphingomyelinase deficiency (ASMD). Anaphylaxis is a very rare and life-threatening adverse reaction described for this drug. Here, we report the case of a 2-year-old boy affected by chronic neurovisceral ASMD who experienced signs of hypersensitivity reactions to olipudase alfa since the administered dose of 1 mg/kg during dose escalation and a proper anaphylactic reaction during the second administration of the target therapeutic dose of 3 mg/kg. The treatment was stopped for 15 weeks and then a 7-step desensitization protocol with the infused dose of 0.03 mg/kg was applied. Subsequent gradual dose escalation was resumed, successfully reaching the dose of 0.3 mg/kg. Moreover, biochemical, and radiological disease indexes, which were increased during treatment discontinuation, have gradually improved since the restart of treatment. However, at the second administration of the dose of 0.6 mg/kg, the patient experienced another adverse drug reaction with facial urticarial rash and bronchospasm, requiring the administration of adrenaline, methylprednisolone, and inhaled salbutamol. This case report highlights the need to customize the olipudase alfa desensitization protocol according to individual tolerance and raises the issue of achieving the established therapeutic target in the most sensitive children.

Synopsis

We report a case of anaphylaxis to olipudase alfa in a child affected by chronic neurovisceral Acid sphingomyelinase deficiency (ASMD) and describe a 7-step desensitization procedure. This procedure, with the total administered dose of 0.03 mg/kg, followed by gradual dose escalation, allowed to reach the dose of 0.3 mg/kg without adverse reactions; however, at the second administration of the dose of 0.6 mg/kg our patient presented another adverse reaction suggesting the need of a different desensitization strategy.

Protein substitutes (PS) without tyrosine (Tyr) and phenylalanine (Phe), are an essential source of synthetic protein in the treatment of tyrosinemia (HT). In the UK, the only available protein substitutes for HT are Tyr/ Phe free amino acid liquid or powders or formulations based on glycomacropeptide (CGMP). A tablet Tyr/ Phe free amino acid supplement (AAT) has now been introduced. The aim of this two-part prospective, longitudinal intervention study was to assess the efficacy, acceptability, and tolerance of AAT in children aged >8 years with HTI. Part 1: was a 28-day acceptability/ tolerance study, part 2, was a 12-month extension study examining efficacy of AAT. Anthropometry and blood Tyr/ Phe were assessed. All subjects were taking NTBC [2-(2-nitro-4-triflourothybenzoyl) cyclohexane-1, 3-dione] with a Tyr restricted diet. Eight subjects with HTI were recruited 4 boys, and 4 girls with a median age of 14.3y (range 10.4–17.3); 3 were Caucasian and 5 of Pakistani origin. The median (range) protein equivalent from PS was 60 g/d (50–60), natural protein 20 g/d (15–30), and NTBC 30 mg/d (25–80). No subjects were taking Phe supplements. Five (63%) subjects completed part 1, with 4 taking all their PS requirements as AAT. Subjects reported AAT were tasteless and had no odour. No adverse gastrointestinal symptoms were recorded, with two reporting improvements in abdominal discomfort. At 12 months, 4 subjects had a non-significant decrease in blood Tyr/ Phe compared to the 12 months pre-treatment. Median blood Tyr (μmol/ L) pre-intervention was 500 (320–590); and at 12 months, 450 (290–530). Median blood Phe (μmol/L) pre-intervention was 40 (30–40); and at 12 months 30 (30–50). Median height z scores remained unchanged, but there was a small decrease in weight z score (pre-study weight − 0.1 (−1.4 to1.1), 12 m − 0.3 (−1.4 to 1.3) and BMI (pre- study BMI 0.2 (−2 to 1.4), and 12 m, −0.1 (−2.5 to 1.5)).

Conclusion

AAT were useful for some adolescents with HTI who struggled with the taste and volume of conventional powdered and liquid PS.