Multiple sulfatase deficiency with neonatal manifestation

Late infantile form of multiple sulfatase deficiency with a novel missense variant in the SUMF1 gene: case report and review

BACKGROUND

Multiple sulfatase deficiency (MSD) is a rare lysosomal storage disorder caused due to pathogenic variants in the SUMF1 gene. The SUMF1 gene encodes for formylglycine generating enzyme (FGE) that is involved in the catalytic activation of the family of sulfatases. The affected patients present with a wide spectrum of clinical features including multi-organ involvement. To date, almost 140 cases of MSD have been reported worldwide, with only four cases reported from India. The present study describes two cases of late infantile form of MSD from India and the identification of a novel missense variant in the SUMF1 gene.

CASE PRESENTATION

In case 1, a male child presented to us at the age of 6 years. The remarkable presenting features included ichthyosis, presence of irritability, poor social response, thinning of corpus callosum on MRI and, speech regression. Clinical suspicion of MSD was confirmed by enzyme analysis of two sulfatase enzymes followed by gene sequencing. We identified a novel missense variant c.860A > T (p.Asn287Ile) in exon 7 of the SUMF1 gene. In case 2, a two and a half years male child presented with ichthyosis, leukodystrophy and facial dysmorphism. We performed an enzyme assay for two sulfatases, which showed significantly reduced activities thereby confirming MSD diagnosis.

CONCLUSION

Overall, present study has added to the existing data on MSD from India. Based on the computational analysis, the novel variant c.860A > T identified in this study is likely to be associated with a milder phenotype and prolonged survival.

Single-nucleotide polymorphisms in the sulfatase-modifying factor 1 gene are associated with lung function and COPD

Single nucleotide polymorphisms (SNPs) in various genes have been shown to associate with COPD, suggesting a role in disease pathogenesis. Sulfatase modifying factor (SUMF1) is a key modifier in connective tissue remodelling, and we have shown previously that several SNPs in SUMF1 are associated with COPD. The aim of this study was to investigate the association between SUMF1 SNPs and advanced lung function characteristics. Never-, former and current smokers with (n=154) or without (n=405) COPD were genotyped for 21 SNPs in SUMF1 and underwent spirometry, body plethysmography, diffusing capacity of the lung for carbon monoxide (D _LCO) measurement and impulse oscillometry. Four SNPs (rs793391, rs12634248, rs2819590 and rs304092) showed a significantly decreased odds ratio of having COPD when heterozygous for the variance allele, together with a lower forced expiratory volume in 1 s (FEV₁) and FEV₁/forced vital capacity (FVC) ratio and an impaired peripheral resistance and reactance. Moreover, individuals homozygous for the variance allele of rs3864051 exhibited a strong association to COPD, a lower FEV₁/FVC, FEV₁ and D _LCO, and an impaired peripheral resistance and reactance. Other SNPs (rs4685744, rs2819562, rs2819561 and rs11915920) were instead associated with impaired lung volumes and exhibited a lower FVC, total lung capacity and alveolar volume, in individuals having the variance allele. Several SNPs in the SUMF1 gene are shown to be associated with COPD and impaired lung function. These genetic variants of SUMF1 may cause a deficient sulfation balance in the extracellular matrix of the lung tissue, thereby contributing to the development of COPD.

Multiple Sulfatase Deficiency (MSD): Review of the Literature and Case Reports of Two Siblings with Dental Caries and Trauma

Multiple sulfatase deficiency (MSD) (MIM # 272200) is an extraordinarily rare inborn error of metabolism (IEM). The phenotypic spectrum is largely heterogeneous and attributed to the combined effects of deficiencies in the nine sulfatases currently known to be related to human diseases. Systemic sequelae of MSD are vast and multisystemic, primarily encompassing developmental delay and neurological, cardiopulmonary, dermatological, gastroenterological, and skeletal manifestations. The dental phenotype is scarcely described in the literature due to a paucity of cases. Dental treatment under local and general anaesthesia mandates an integrated multidisciplinary approach to safeguard systemic health and optimise outcomes. This paper presents two siblings with multiple sulfatase deficiency who presented to the Paediatric Dental Department at Great Ormond Street Hospital, requiring comprehensive care under general anaesthesia for dental caries and trauma.

Natural history of multiple sulfatase deficiency: Retrospective phenotyping and functional variant analysis to characterize an ultra-rare disease

Multiple sulfatase deficiency (MSD) is an ultra-rare neurodegenerative disorder caused by pathogenic variants in SUMF1. This gene encodes formylglycine-generating enzyme (FGE), a protein required for sulfatase activation. The clinical course of MSD results from additive effect of each sulfatase deficiency, including metachromatic leukodystrophy (MLD), several mucopolysaccharidoses (MPS II, IIIA, IIID, IIIE, IVA, VI), chondrodysplasia punctata, and X-linked ichthyosis. While it is known that affected individuals demonstrate a complex and severe phenotype, the genotype-phenotype relationship and detailed clinical course is unknown. We report on 35 cases enrolled in our retrospective natural history study, n = 32 with detailed histories. Neurologic function was longitudinally assessed with retrospective scales. Biochemical and computational modeling of novel SUMF1 variants was performed. Genotypes were classified based on predicted functional change, and each individual was assigned a genotype severity score. The median age at symptom onset was 0.25 years; median age at diagnosis was 2.7 years; and median age at death was 13 years. All individuals demonstrated developmental delay, and only a subset of individuals attained ambulation and verbal communication. All subjects experienced an accumulating systemic symptom burden. Earlier age at symptom onset and severe variant pathogenicity correlated with poor neurologic outcomes. Using retrospective deep phenotyping and detailed variant analysis, we defined the natural history of MSD. We found that attenuated cases can be distinguished from severe cases by age of onset, attainment of ambulation, and genotype. Results from this study can help inform prognosis and facilitate future study design.

A homozygous missense variant of SUMF1 in the Bedouin population extends the clinical spectrum in ultrarare neonatal multiple sulfatase deficiency

BACKGROUND

Multiple sulfatase deficiency (MSD, MIM #272200) is an ultrarare congenital disorder caused by SUMF1 mutation and often misdiagnosed due to its complex clinical presentation. Impeded by a lack of natural history, knowledge gained from individual case studies forms the source for a reliable diagnosis and consultation of patients and parents.

METHODS

We collected clinical records as well as genetic and metabolic test results from two MSD patients. The functional properties of a novel SUMF1 variant were analyzed after expression in a cell culture model.

RESULTS

We report on two MSD patients-the first neonatal type reported in Israel-both presenting with this most severe manifestation of MSD. Our patients showed uniform clinical symptoms with persistent pulmonary hypertension, hypotonia, and dysmorphism at birth. Both patients were homozygous for the same novel SUMF1 mutation (c.1043C>T, p.A348V). Functional analysis revealed that the SUMF1-encoded variant of formylglycine-generating enzyme is highly instable and lacks catalytic function.

CONCLUSION

The obtained results confirm genotype-phenotype correlation in MSD, expand the spectrum of clinical presentation and are relevant for diagnosis including the extremely rare neonatal severe type of MSD.

Inhibition of endogenous miR-23a/miR-377 in CHO cells enhances difficult-to-express recombinant lysosomal sulfatase activity

Difficult-to-express (DTE) recombinant proteins such as multi-specific proteins, DTE monoclonal antibodies, and lysosomal enzymes have seen difficulties in manufacturability using Chinese hamster ovary (CHO) cells or other mammalian cells as production platforms. CHO cells are preferably used for recombinant protein production for their ability to secrete human-like recombinant proteins with posttranslational modification, resistance to viral infection, and familiarity with drug regulators. However, despite huge progress made in engineering CHO cells for high volumetric productivity, DTE proteins like recombinant lysosomal sulfatase represent one of the poorly understood proteins. Furthermore, there is growing interest in the use of microRNA (miRNA) to engineer CHO cells expressing DTE proteins to improve cell performance of relevant bioprocess phenotypes. To our knowledge, no research has been done to improve CHO cell production of DTE recombinant lysosomal sulfatase using miRNA. We identified miR-23a and miR-377 as miRNAs predicted to target SUMF1, an activator of sulfatases, using in silico prediction tools. Transient inhibition of CHO endogenous miR-23a/miR-377 significantly enhanced recombinant sulfatase enzyme-specific activity by ~15-21% compared to scramble without affecting cell growth. Though inhibition of miR-23a/miR-377 had no significant effect on the mRNA and protein levels of SUMF1, overexpression of miR-23a/377 caused ~30% and ~27-29% significant reduction in endogenous SUMF1 protein and mRNA expression levels, respectively. In summary, our data demonstrate the importance of using miRNA to optimize the CHO cell line secreting DTE recombinant lysosomal sulfatase.

Severe neonatal multiple sulfatase deficiency presenting with hydrops fetalis in a preterm birth patient

Multiple sulfatase deficiency (MSD) is an ultra-rare lysosomal storage disorder (LSD). Mutations in the SUMF1 gene encoding the formylglycine generating enzyme (FGE) result in an unstable FGE protein with reduced enzymatic activity, thereby affecting the posttranslational activation of newly synthesized sulfatases. Complete absence of FGE function results in the most severe clinical form of MSD with neonatal onset and rapid deterioration. We report on a preterm infant presenting with hydrops fetalis, lung hypoplasia, and dysmorphism as major clinical signs. The patient died after 6 days from an intraventricular hemorrhage followed by multi-organ failure. MSD was caused by a homozygous SUMF1 stop mutation (c.191C>A, p.Ser64Ter). FGE protein and sulfatase activities were absent in patient fibroblasts. Hydrops fetalis is a rare symptom of LSDs and should be considered in the differential diagnosis in combination with dysmorphism. The diagnostic set up should include measurements of glycosaminoglycan excretion and lysosomal enzyme activities, among them at least two sulfatases, and molecular confirmation.

Label-Free Quantitative Proteomics in a Methylmalonyl-CoA Mutase-Silenced Neuroblastoma Cell Line

Methylmalonic acidemias (MMAs) are inborn errors of metabolism due to the deficient activity of methylmalonyl-CoA mutase (MUT). MUT catalyzes the formation of succinyl-CoA from methylmalonyl-CoA, produced from propionyl-CoA catabolism and derived from odd chain fatty acids β-oxidation, cholesterol, and branched-chain amino acids degradation. Increased methylmalonyl-CoA levels allow for the presymptomatic diagnosis of the disease, even though no approved therapies exist. MMA patients show hyperammonemia, ketoacidosis, lethargy, respiratory distress, cognitive impairment, and hepatomegaly. The long-term consequences concern neurologic damage and terminal kidney failure, with little chance of survival. The cellular pathways affected by MUT deficiency were investigated using a quantitative proteomics approach on a cellular model of MUT knockdown. Currently, a consistent reduction of the MUT protein expression was obtained in the neuroblastoma cell line (SH-SY5Y) by using small-interfering RNA (siRNA) directed against an MUT transcript (MUT siRNA). The MUT absence did not affect the cell viability and apoptotic process in SH-SY5Y. In the present study, we evaluate and quantify the alterations in the protein expression profile as a consequence of MUT-silencing by a mass spectrometry-based label-free quantitative analysis, using two different quantitative strategies. Both quantitative methods allowed us to observe that the expression of the proteins involved in mitochondrial oxido-reductive homeostasis balance was affected by MUT deficiency. The alterated functional mitochondrial activity was observed in siRNA_MUT cells cultured with a propionate-supplemented medium. Finally, alterations in the levels of proteins involved in the metabolic pathways, like carbohydrate metabolism and lipid metabolism, were found.

Complex care of individuals with multiple sulfatase deficiency: Clinical cases and consensus statement

Multiple sulfatase deficiency (MSD) is an ultra-rare neurodegenerative disorder that results in defective sulfatase post-translational modification. Sulfatases in the body are activated by a unique protein, formylglycine-generating enzyme (FGE) that is encoded by SUMF1. When FGE is absent or insufficient, all 17 known human sulfatases are affected, including the enzymes associated with metachromatic leukodystrophy (MLD), several mucopolysaccharidoses (MPS II, IIIA, IIID, IVA, VI), chondrodysplasia punctata, and X-linked ichthyosis. As such, individuals demonstrate a complex and severe clinical phenotype that has not been fully characterized to date. In this report, we describe two individuals with distinct clinical presentations of MSD. Also, we detail a comprehensive systems-based approach to the management of individuals with MSD, from the initial diagnostic evaluation to unique multisystem issues and potential management options. As there have been no natural history studies to date, the recommendations within this report are based on published studies and consensus opinion and underscore the need for future research on evidence-based outcomes to improve management of children with MSD.

A Patient With Atypical Multiple Sulfatase Deficiency

BACKGROUND

Multiple sulfatase deficiency is an autosomal recessive lysosomal storage disorder characterized by the absence of several sulfatases and resulting from mutations in the gene encoding the human C (alpha)-formylglycine-generating enzyme. There have been a variety of biochemical and clinical presentations reported in this disorder.

PATIENT DESCRIPTION

We present a 4-year-old girl with clinical findings of microcephaly, spondylolisthesis and neurological regression without ichthyosis, coarse facies, and organomegaly.

RESULTS

The child's magnetic resonance imaging demonstrated confluent white matter abnormalities involving the periventricular and deep cerebral white matter with the U-fibers relatively spared. Biochemical testing showing low arylsulfatase A levels were initially thought to be consistent with a diagnosis of metachromatic leukodystrophy. The diagnosis of multiple sulfatase deficiency was pursued when genetic testing for metachromatic leukodystrophy was negative.

CONCLUSION

This child illustrates the clinical heterogeneity of multiple sulfatase deficiency and that this disorder can occur without the classic clinical features.