Mucopolysaccharidosis type IVA (MPS IVA, Morquio A syndrome) is a rare lysosomal storage disease primarily characterized by severe skeletal dysplasia. Clinical and laboratory data, including treatment responses, are reported for a cohort of Czech patients with MPS IVA. Nineteen patients with MPS IVA from 17 families (13 M/6F) were included; only one patient exhibited a mild form. The median age at first symptom onset was 3.0 years (IQR 1.6–3.4), whereas the median age at confirmed diagnosis was 5.0 years (IQR 3.9–5.7). At the time of diagnosis, all patients had skeletal symptoms (pectus carinatum in 58

Background:Mucopolysaccharidosis type IVA (MPS IVA, Morquio A syndrome) is a rare lysosomal storage disease primarily characterized by severe skeletal dysplasia. Clinical and laboratory data, including treatment responses, are reported for a cohort of Czech patients with MPS IVA. Results:Nineteen patients with MPS IVA from 17 families (13M/6F) were included; only one patient exhibited a mild form. The median age at disease onset was 3.0 ± 1.4 years, whereas the median age at confirmed diagnosis was 5.0 ± 3.5 years. At the time of diagnosis, all patients had skeletal symptoms (pectus carinatum in 58%, short stature in 47%, hip dysplasia in 47%), and 63% had nonskeletal symptoms. Each patient underwent at least one surgical procedure (77% knee, 59% spine, 41% adenotomy). On spinal MRI, 76% of patients presented with cervical stenosis, and 41% presented with cervical myelopathy. Eight patients received ERT for a median duration of 5.5 ± 2.6 years. Compared with non-ERT patients from natural history studies and non-ERT patients within our cohort, beneficial effects were evident in monitored parameters such as changes in the mean FVC and FEV1 volumes and the mean 6MWT distance. Additionally, the hidradenitis suppurativa observed in three patients improved with biologic therapy. We also describe two novel mutations (c.421_422dupTG, c.482G>C). Conclusions:Documenting the natural history of MPS IVA in this population may aid in early diagnosis. Despite the disease's progressive nature, ERT was effective in our MPS IVA patients, demonstrating a consistent impact on endurance across all age groups.

Our understanding of the genetic landscape of inherited optic neuropathies has grown significantly over the past decades, and it is now known to involve many genes found in both the nuclear and mitochondrial genomes, exhibiting all possible inheritance patterns. Furthermore, pathogenic variants in nuclear genes of mitochondrial respiratory Complex I (CI) subunits have been identified in some cases of ION, in addition to the more common severe presentation of CI deficiencies, usually with early onset. We conducted NGS screening of CI genes to identify potential causative variants in patients with optic atrophy, also performing comprehensive clinical assessments, including neuroimaging studies (MRI) and neurological evaluations. Detailed molecular structure modeling was performed to better evaluate the damaging effects of both novel and previously reported variants in the relevant CI subunits. We identified and characterized candidate causative variants in 31 patients from 23 unrelated families, with biallelic or hemizygous variants in 11 different nuclear CI-related genes encoding polypeptides involved in the structure of CI, including 3 core subunits (NDUFS7, NDUFV1, NDUFV2), 4 accessory subunits (NDUFA1, NDUFA10, NDUFA12, NDUFB11), and 4 assembly factors (NDUFAF2, NDUFAF3, NDUFAF4, NDUFAF8). Notably, defects in core CI subunits in this cohort lead to isolated optic atrophy, while defects in accessory CI subunits and assembly factors resulted in a spectrum of phenotypes, from isolated to syndromic optic atrophy. For 12 cases, the subacute onset of vision loss enabled us to associate or confirm novel genes (NDUFS7, NDUFV1, NDUFAF2, NDUFAF4, NDUFAF8) with the autosomal recessive Leber Hereditary Optic Neuropathy (arLHON) phenotype. Moreover, in the NDUFS7 subunit a partial spatial segregation was noted for missense variants causing either Leigh syndrome or isolated optic atrophy, hinting at possible disease-specific molecular defects. Our case series broadens the genetic spectrum of inherited optic neuropathies, emphasizing the crucial role of nuclear CI genes in its pathogenesis. The arLHON phenotype emerges as linked to numerous nuclear CI genes for which an insidious onset of optic atrophy is also reported, and in some cases the same variant may underlie both phenotypes. Overall, we highlight the possibly so far underestimated prevalence of CI nuclear subunits in the molecular diagnosis of ION, prompting to include all CI-related genes in the standard diagnostic screening.

BackgroundNewborns undergo rapid metabolic and organ adaptations after birth, which are compromised in premature newborns, leading to adverse health outcomes. Molecular mechanisms underlying these transitions remain poorly understood due to limited tissue availability. To address this gap, we characterized tissue transcriptomes using autopsy samples from a unique newborn cohort.MethodsWe analyzed liver (LI), heart (HM), and skeletal muscle (SM) transcriptomes using RNA sequencing in 41 predominantly premature newborns who died shortly after birth. Nearly 14,000 protein-coding gene transcripts per tissue were detected.ResultsTissues exhibited distinct expression profiles, with LI showed the highest number of tissue-specific genes. SM gene expression correlated strongly with gestational age at birth (i.e., the prenatal development), while LI was influenced by the duration of postnatal survival (i.e., the postnatal development). HM displayed minimal changes, suggesting stable myocardial metabolism during the perinatal transition. Weighted Gene Co-expression Network Analysis (WGCNA) identified tissue-specific gene co-expression modules linked to clinical traits such as gestational age, birth weight, survival duration, nutrition, and exposure to catecholamine treatment. The key functional annotations, validated by differential expression analysis, revealed that LI and SM modules were enriched for mitochondrial metabolism and oxidative phosphorylation genes, with more pronounced prenatal development in SM, and a postnatal increase in both tissues. Data suggests that energy metabolism in SM matures first, followed by the development of muscle functions. Hepatic modules were associated with a postnatal increase in the steroid hormone/xenobiotic metabolism, and a decline in hematopoietic activity. Robust annotations to ribosome activity suggested tissue-specific changes in protein synthesis, which declined prenatally in SM, postnatally in HM. Notably, the supply of exogenous glucose and nutrition type were strongly associated with hepatic gene expression, highlighting the central role of the liver in postnatal metabolic adaptation.ConclusionOverall, our study highlights tissue-specific perinatal gene regulation, with mitochondrial maturation emerging as a crucial driver of postnatal adaptation, explaining vulnerabilities in preterm infants. We provide a unique resource for characterizing developmental changes in tissue transcriptomes during the fetal-to-neonatal transition in human newborns.

Mitochondrial diseases are severe, inherited metabolic disorders that affect the paediatric population. They affect the functioning of mitochondrial oxidative phosphorylation (OXPHOS) apparatus either directly or indirectly. Since mutations in mtDNA are responsible for only 25% of paediatric cases and next-generation sequencing does not always provide a conclusive diagnosis, the biochemical approach still represents a valuable tool in diagnostics. Mitochondrial defects can be identified in tissue biopsies (muscle or skin). However, they also often manifest in peripheral blood cells. We developed a protocol for isolation and cryopreservation of peripheral blood mononuclear cells (PBMCs) from 5 ml of children's blood using Ficoll centrifugation which can be utilised for subsequent functional measurements on thawed samples. Furthermore, we evaluated the diagnostic utility of the optimised high-resolution oxygraphy protocol using digitonin-permeabilized cryopreserved PBMCs on 47 samples from patients with confirmed or suspected mitochondrial disease. Overall, the diagnosis was confirmed in 72% of cases, while the analysis of cryopreserved PBMCs provided a false negative outcome in 13% of cases. Our study demonstrates a sensitive, fast, and non-invasive approach for the diagnostics of various types of mitochondrial disorders, especially those of nuclear genetic origin manifesting in paediatric patients.

Cardiac involvement (CI) in phosphomannomutase 2-congenital disorders of glycosylation (PMM2-CDG) is part of the multisystemic presentation contributing to high mortality rates. The most common cardiac manifestations are pericardial effusion, cardiomyopathy, and structural heart defects. A genotype-phenotype correlation with organ involvement has not yet been described. We analyzed clinical, biochemical, and molecular genetic data of 222 patients from eight European centers and characterized the natural course of patients with CI. Fifty-seven patients (45 children) presented with CI, of whom 24 died (median age 21 months, standard deviation 49.8). Pericardial effusion was the most frequent manifestation (55.4%), occurring mostly within the first 6 months of life. The most common pathogenic variants in patients with CI were p.(Arg141His) in 74%, followed by p.(Val231Met) in 36%, which is 3.5 times higher than in PMM2-CDG patients without CI (p < 0.0001). Twenty-one out of 36 patients with p.(Val231Met) had CI; among them, 15 died, compared to 33 out of 166 patients without p.(Val231Met) who had CI (p < 0.0001). Nine out of 33 patients died (p = 0.0015), indicating greater clinical severity. Furthermore, the p.(Val231Met) variant is predominant in Eastern Europe, suggesting a founder effect. Cardiac complications in PMM2-CDG patients are common and serious. The variant p.(Val231Met) profoundly influences the extent of CI and mortality rates. Therefore, we recommend cardiac surveillance be included in the follow-up protocols for PMM2-CDG.

Tyrosinemie typ 1 (TYR 1) je vzácné autosomálně recesivní onemocnění z okruhu dědičných poruch metabolismu aminokyselin. Podkladem jsou bialelické mutace v genu FAH, vedoucí k poruše aktivity fumarylacetoacetáthydrolázy, klíčového enzymu v metabolismu tyrosinu. U dětí s TYR 1 dochází alternativní metabolickou cestou k nadprodukci toxických metabolitů, především sukcinylacetonu a fumarylacetoacetátu, které poškozují hepatocyty a tubulární buňky ledvin. Klinicky se TYR 1 projevuje akutní formou jaterního a renálního selhávání v kojeneckém věku nebo chronicky rozvojem jaterní fibrózy, cirhózy, křivice a hepatocelulárního karcinomu v kojeneckém nebo batolecím věku, časté jsou i porfyrické krize. Biochemická diagnostika je založena na průkazu zvýšených hladin sukcinylacetonu v krvi i moči, eventuálně doprovázených elevací tyrosinu a stoupající hladinou alfa-fetoproteinu. Diagnostiku je třeba potvrdit na molekulární úrovni. V léčbě se používá nitisinon, který blokuje produkci toxických metabolitů, v kombinaci s nízkobílkovinnou dietou suplementovanou směsí esenciálních aminokyselin bez tyrosinu a fenylalaninu. Pokud konzervativní terapie nezabrání progresi jaterního selhávání nebo rozvoji hepatocelulárního karcinomu, je indikována transplantace jater. V našem sdělení předkládáme klinický průběh onemocnění u 10měsíčního chlapce, u kterého se onemocnění projevilo hepatopatií, melénou a hepatocelulárním karcinomem. Kromě nitisinonu a diety byla nutná chemoembolizace přívodné jaterní arterie v oblasti nej rychleji rostoucího karcinomu, která umožnila získat čas na přípravu k transplantaci jater. Po úspěšné transplantaci byla metabolická léčba ukončena, chlapec prospívá a je v dobrém klinickém stavu.

BACKGROUND:Pathogenic variants in the ATAD3A gene lead to a heterogenous clinical picture and severity ranging from recessive neonatal-lethal pontocerebellar hypoplasia through milder dominant Harel-Yoon syndrome up to, again, neonatal-lethal but dominant cardiomyopathy. The genetic diagnostics of ATAD3A-related disorders is also challenging due to three paralogous genes in the ATAD3 locus, making it a difficult target for both sequencing and CNV analyses.RESULTS:Here we report four individuals from two families with compound heterozygous p.Leu77Val and exon 3-4 deletion in the ATAD3A gene. One of these patients was characterized as having combined OXPHOS deficiency based on decreased complex IV activities, decreased complex IV, I, and V holoenzyme content, as well as decreased levels of COX2 and ATP5A subunits and decreased rate of mitochondrial proteosynthesis. All four reported patients shared a strikingly similar clinical picture to a previously reported patient with the p.Leu77Val variant in combination with a null allele. They presented with a less severe course of the disease and a longer lifespan than in the case of biallelic loss-of-function variants. This consistency of the phenotype in otherwise clinically heterogenous disorder led us to the hypothesis that the severity of the phenotype could depend on the severity of variant impact. To follow this rationale, we reviewed the published cases and sorted the recessive variants according to their impact predicted by their type and the severity of the disease in the patients.CONCLUSION:The clinical picture and severity of ATAD3A-related disorders are homogenous in patients sharing the same combinations of variants. This knowledge enables deduction of variant impact severity based on known cases and allows more accurate prognosis estimation, as well as a better understanding of the ATAD3A function.

Leber hereditary optic neuropathy is a primary mitochondrial disease characterized by acute visual loss due to the degeneration of retinal ganglion cells. In this study, we describe a patient carrying a rare missense heteroplasmic variant in MT-ND1, NC_012920.1:m.4135T>C (p.Tyr277His) manifesting with a typical bilateral painless decrease of the visual function, triggered by physical exercise or higher ambient temperature. Functional studies in muscle and fibroblasts show that amino acid substitution Tyr277 with His leads to only a negligibly decreased level of respiratory chain complex I (CI), but the formation of supercomplexes and the activity of the enzyme are disturbed noticeably. Our data indicate that although CI is successfully assembled in the patient’s mitochondria, its function is hampered by the m.4135T>C variant, probably by stabilizing CI in its inactive form. We conclude that the m.4135T>C variant together with a combination of external factors is necessary to manifest the phenotype.

Tyrosinemia type 1 (HT1) is an inborn error of tyrosine catabolism that leads to severe liver, kidney, and neurological dysfunction. Newborn screening (NBS) can enable a timely diagnosis and early initiation of treatment. We presented the follow up of the only two Slovenian patients diagnosed with HT1. Metabolic control was monitored by measuring tyrosine, phenylalanine and succinylacetone from dried blood spots (DBSs). Retrograde screening of HT1 was performed from DBSs taken at birth using tandem mass spectrometry. First patient was diagnosed at the age of 6 months in the asymptomatic phase due to an abnormal liver echogenicity, the other presented at 2.5 months with an acute liver failure and needed a liver transplantation. The first was a compound heterozygote for a novel FAH intronic variant c.607-21A>G and c.192G>T whereas the second was homozygous for c.192G>T. At the non-transplanted patient, 66% of tyrosine and 79% of phenylalanine measurements were in strict reference ranges of 200-400 mu mol/L and >30 mu mol/L, respectively, which resulted in a favorable cognitive outcome at 3.6 years. On retrograde screening, both patients had elevated SA levels; on the other hand, tyrosine was elevated only at one. We showed that non-coding regions should be analyzed when clinical and biochemical markers are characteristic of HT1. DBSs represent a convenient sample type for frequent amino acid monitoring. Retrograde diagnosis of HT1 was possible after more than three years of birth with SA as a primary marker, complemented by tyrosine.