Clinical and genetic characteristics of a patient with phosphoribosyl pyrophosphate synthetase 1 deficiency and a systematic literature review

Phosphoribosylpyrophosphate synthetase 1 (PRS-I) is an enzyme involved in nucleotide metabolism. Pathogenic variants in the PRPS1 are rare and PRS-I deficiency can manifest as three clinical syndromes: X-linked non-syndromic sensorineural deafness (DFN2), X-linked Charcot-Marie-Tooth neuropathy type 5 (CMTX5) and Arts syndrome. We present a Slovenian patient with PRS-I enzyme deficiency due to a novel pathogenic variant - c.424G > A (p.Val142Ile) in the PRPS1 gene, who presented with gross motor impairment, severe sensorineural deafness, balance issues, ataxia, and frequent respiratory infections. In addition, we report the findings of a systemic literature review of all described male cases of Arts syndrome and CMTX5 as well as intermediate phenotypes. As already proposed by other authors, our results confirm PRS-I deficiency should be viewed as a phenotypic continuum rather than three separate syndromes because there are multiple reports of patients with an intermediary clinical presentation.

Newborn Screening in a Pandemic-Lessons Learned

The COVID-19 pandemic affected many essential aspects of public health, including newborn screening programs (NBS). Centers reported missing cases of inherited metabolic disease as a consequence of decreased diagnostic process quality during the pandemic. A number of problems emerged at the start of the pandemic, but from the beginning, solutions began to be proposed and implemented. Contingency plans were arranged, and these are reviewed and described in this article. Staff shortage emerged as an important issue, and as a result, new work schedules had to be implemented. The importance of personal protective equipment and social distancing also helped avoid disruption. Staff became stressed, and this needed to be addressed. The timeframe for collecting bloodspot samples was adapted in some cases, requiring reference ranges to be modified. A shortage of essential supplies and protective equipment was evident, and laboratories described sharing resources in some situations. The courier system had to be adapted to make timely and safe transport possible. Telemedicine became an essential tool to enable communication with patients, parents, and medical staff. Despite these difficulties, with adaptations and modifications, some centers evaluated candidate conditions, continued developments, or began new NBS. The pandemic can be regarded as a stress test of the NBS under real-world conditions, highlighting critical aspects of this multidisciplinary system and the need for establishing local, national, and global strategies to improve its robustness and reliability in times of shortage and overloaded national healthcare systems.

Comparison of Tandem Mass Spectrometry and the Fluorometric Method-Parallel Phenylalanine Measurement on a Large Fresh Sample Series and Implications for Newborn Screening for Phenylketonuria

Phenylketonuria (PKU) was the first disease to be identified by the newborn screening (NBS) program. Currently, there are various methods for determining phenylalanine (Phe) values, with tandem mass spectrometry (MS/MS) being the most widely used method worldwide. We aimed to compare the MS/MS method with the fluorometric method (FM) for measuring Phe in the dried blood spot (DBS) and the efficacy of both methods in the NBS program. The FM was performed using a neonatal phenylalanine kit and a VICTOR2^TM D fluorometer. The MS/MS method was performed using a NeoBase^TM 2 kit and a Waters Xevo TQD mass spectrometer. The Phe values measured with the MS/MS method were compared to those determined by the FM. The cut-off value for the NBS program was set at 120 µmol/L for FM and 85 µmol/L for MS/MS. We analyzed 54,934 DBS. The measured Phe values varied from 12 to 664 µmol/L, with a median of 46 µmol/L for the MS/MS method and from 10 to 710 µmol/L, with a median of 70 µmol/L for the FM. The Bland-Altman analysis indicated a bias of -38.9% (-23.61 µmol/L) with an SD of 21.3% (13.89 µmol/L) when comparing the MS/MS method to the FM. The Phe value exceeded the cut-off in 187 samples measured with FM and 112 samples measured with MS/MS. The FM had 181 false positives, while the MS/MS method had 106 false positives. Our study showed that the MS/MS method gives lower results compared to the FM. Despite that, none of the true positives would be missed, and the number of false-positive results would be significantly lower compared to the FM.

Compound Heterozygote Mutation in the SMPD1 Gene Leading to Nieman-Pick Disease Type A

BACKGROUND Niemann-Pick disease (NPD) type A is an autosomal recessive lipid storage disorder caused by acid sphingomyelinase deficiency due to a mutation in the SMPD1 gene. Type A is the most severe phenotype of NPD, with early onset in infancy and unfavorable outcome in early childhood. CASE REPORT An 11-month-old boy with hepatosplenomegaly, elevated liver transaminases, and faltering growth was admitted to our hospital for further assessment of potential liver disease. He had severe generalized muscular hypotonia, muscular hypotrophy, reduced muscular strenght, joint laxity, weak deep tendon reflexes, and severe motor developmental delay. Leukodystrophy was seen on the brain MRI, and brainstem auditory evoked potentials were characteristic for auditory neuropathy. A chest X-ray showed signs of interstitial lung disease, which was not further evaluated due to absence of respiratory distress. Liver biopsy histopathologic findings were indicative for lipid storage disease. Genetic analysis showed that the patient is a compound heterozygote in the SMPD1 gene - (NM_000543.5): c.573delT p.(Ser192Alafs*65), which was inherited from the mother and c.1267C>T p.(His423Tyr) was inherited from the father. Both variants were previously individually reported in NPD type A and B. The clinical phenotype in our patient was characteristic of NPD type A, with an early onset and a rapidly progresive neurodegeneration. The patient was included in multidisciplinary follow-up, providing him symptomatic treatment and support. CONCLUSIONS We present a case of NPD type A caused by a rare compound heterozygote mutation in the SMPD1 gene. Most clinical findings and the disease course were typical for NPD type A, except for bilateral auditory neuropathy, which seems to be an uncommon finding in this phenotype and could be underestimated due to infrequent testing for auditory dysfunction.

Early Discovery of Children With Lysosomal Acid Lipase Deficiency With the Universal Familial Hypercholesterolemia Screening Program

Lysosomal acid lipase deficiency (LAL-D) is an autosomal recessive lysosomal storage disorder, caused by homozygous or compound heterozygous pathogenic variants in the LIPA gene. Clinically, LAL-D is under- and misdiagnosed, due to similar clinical and laboratory findings with other cholesterol or liver misfunctions. As a part of the Slovenian universal familial hypercholesterolemia (FH) screening, LAL-D is screened as a secondary condition among other rare dyslipidemias manifesting with hypercholesterolemia. Out of 669 children included, three were positive for a homozygous disease-causing splicing variant NM_000235.4: c.894G > A (NP_000226.2:p. Gln298Gln) in the LIPA gene (NG_008194.1). The mean age by the diagnosis of LAL-D was 9.8 ± 0.9 years. Moreover, all three LAL-D-positive children had an important elevation of transaminases and decreased activity of the lysosomal acid lipase enzyme. Abdominal MRI in all children detected an enlarged liver but a normal-sized spleen. In conclusion, universal FH screening algorithms with the confirmatory genetic analysis in the pediatric population enable also rare dyslipidemia detection at an early age. An important clinical criterion for differentiation between FH and the LAL-D-positive children has elevated transaminase levels (AST and ALT). In all three LAL-D positive children, an improvement in cholesterol and transaminase levels and steatosis of the liver has been seen after early treatment initiation.

Efficacy and safety of empagliflozin in glycogen storage disease type Ib: Data from an international questionnaire

PURPOSE

This paper aims to report collective information on safety and efficacy of empagliflozin drug repurposing in individuals with glycogen storage disease type Ib (GSD Ib).

METHODS

This is an international retrospective questionnaire study on the safety and efficacy of empagliflozin use for management of neutropenia/neutrophil dysfunction in patients with GSD Ib, conducted among the respective health care providers from 24 countries across the globe.

RESULTS

Clinical data from 112 individuals with GSD Ib were evaluated, representing a total of 94 treatment years. The median age at start of empagliflozin treatment was 10.5 years (range = 0-38 years). Empagliflozin showed positive effects on all neutrophil dysfunction-related symptoms, including oral and urogenital mucosal lesions, recurrent infections, skin abscesses, inflammatory bowel disease, and anemia. Before initiating empagliflozin, most patients with GSD Ib were on G-CSF (94/112; 84%). At the time of the survey, 49 of 89 (55%) patients previously treated with G-CSF had completely stopped G-CSF, and another 15 (17%) were able to reduce the dose. The most common adverse event during empagliflozin treatment was hypoglycemia, occurring in 18% of individuals.

CONCLUSION

Empagliflozin has a favorable effect on neutropenia/neutrophil dysfunction-related symptoms and safety profile in individuals with GSD Ib.

Clinical and genetic characteristics of two patients with tyrosinemia type 1 in Slovenia – A novel fumarylacetoacetate hydrolase (FAH) intronic disease-causing variant

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 μmol/L and >30 μmol/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.

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Non-coding region variants of FAH gene can result in a symptomatic HT1.

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Retrograde screening for HT1 is technically possible even three years after birth.

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DBS are convenient for monitoring HT1 patients and are family-friendly.

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Regular monitoring in HT1 patients can result in a favorable cognitive outcome.

Very Long-Chain Acyl-CoA Dehydrogenase Deficiency: High Incidence of Detected Patients With Expanded Newborn Screening Program

Very long-chain acyl-CoA dehydrogenase deficiency (VLCADD) is a rare autosomal recessive disorder of fatty acid metabolism with a variable presentation. The aim of this study was to describe five patients with VLCADD diagnosed through the pilot study and expanded newborn screening (NBS) program that started in 2018 in Slovenia. Four patients were diagnosed through the expanded NBS program with tandem mass spectrometry; one patient was previously diagnosed in a pilot study preceding the NBS implementation. Confirmatory testing consisted of acylcarnitines analysis in dried blood spots, organic acids profiling in urine, genetic analysis of ACADVL gene, and enzyme activity determination in lymphocytes or fibroblasts. Four newborns with specific elevation of acylcarnitines diagnostic for VLCADD and disease-specific acylcarnitines ratios (C14:1, C14, C14:2, C14:1/C2, C14:1/C16) were confirmed with genetic testing: all were compound heterozygotes, two of them had one previously unreported ACDVL gene variant each (NM_000018.3) c.1538C > G; (NP_000009) p.(Ala513Gly) and c.661A > G; p.(Ser221Gly), respectively. In addition, one patient diagnosed in the pilot study also had a specific elevation of acylcarnitines. Subsequent ACDVL genetic analysis confirmed compound heterozygosity. In agreement with the diagnosis, enzyme activity was reduced in five patients tested. In seven other newborns with positive screening results, only single allele variants were found in the ACDVL gene, so the diagnosis was not confirmed. Among these, two variants were novel, c.416T > C and c.1046C > A, respectively (p.Leu139Pro and p.Ala349Glu). In the first 2 years of the expanded NBS program in Slovenia altogether 30,000 newborns were screened. We diagnosed four cases of VLCADD. The estimated VLCADD incidence was 1:7,500 which was much higher than that of the medium-chain acyl-CoA dehydrogenase deficiency (MCADD) cases in the same period. Our study also provided one of the first descriptions of ACADVL variants in Central-Southeastern Europe and reported on 4 novel variants.

Novel Insights Into Monogenic Obesity Syndrome Due to INPP5E Gene Variant: A Case Report of a Female Patient

A Caucasian girl with consanguineous parents presented with early severe obesity and retinal dystrophy. A novel, homozygous gene truncating variant (c.1897C>T) in the INPP5E gene confirmed the diagnosis of MORMS (OMIM #610156). A novel clinical finding in the presented syndrome is progressive cone-rod type retinal dystrophy diagnosed at the age of four months that progressed in the 1^st decade of life. Severe obesity, insulin resistance with hyperinsulinism, and impaired glucose tolerance developed alongside other components of the metabolic syndrome - dyslipidemia, arterial hypertension, and obstructive hypopnea in sleep. At the age of 14 years, primary amenorrhea persists. The patient is managed by regular nutritional advice, metformin, antihypertensive medication, and non-invasive respiratory support during sleep. Differential diagnosis of this rare entity is discussed in extend.

Current Status of Newborn Screening in Southeastern Europe

Significant part of Southeastern Europe (with a population of 76 million) has newborn screening (NBS) programs non-harmonized with developed European countries. Initial survey was conducted in 2013/2014 among 11 countries from the region (Albania, Bulgaria, Bosnia and Herzegovina (BIH), Croatia, Kosovo, Macedonia, Moldova, Montenegro, Romania, Serbia, and Slovenia) to assess the main characteristics of their NBS programs and their future plans. Their cumulative population at that time was ~52,5 million. At that time, none of the countries had an expanded NBS program, while phenylketonuria screening was not introduced in four and congenital hypothyroidism in three of 11 countries. We repeated the survey in 2020 inviting the same 11 countries, adding Cyprus, Greece, Hungary, and Malta (due to their geographical position in the wider region). The aims were to assess the current state, to evaluate the change in the period, and to identify the main obstacles impacting the implementation of expanded NBS and/or reaching a wider population. Responses were collected from 12 countries (BIH-Federation of BIH, BIH-Republic of Srpska, Bulgaria, Croatia, Greece, Hungary, Kosovo, North Macedonia, Malta, Montenegro, Romania, Serbia, Slovenia) with a population of 68.5 million. The results of the survey showed that the regional situation regarding NBS only modestly improved in this period. All of the surveyed countries except Kosovo screened for at least congenital hypothyroidism, while phenylketonuria was not screened in four of 12 countries. Croatia and Slovenia implemented an expanded NBS program using tandem mass spectrometry from the time of last survey. In conclusion, the current status of NBS programs in Southeastern Europe is very variable and is still underdeveloped (or even non-existent) in some of the countries. We suggest establishing an international task-force to assist with implementation and harmonization of basic NBS services where needed.

Precocious puberty in a girl with 3-methylglutaconic aciduria type 1 (3-MGA-I) due to a novel AUH gene mutation

3-methylglutaconic aciduria type 1 (3-MGA-I) (MIM ID #250950) is an ultra-rare, autosomal recessive organic aciduria, resulting from mutated AUH gene, leading to the deficient 3-methylglutaconyl-CoA hydratase (3-MGH). Only around 40 cases are previously reported, caused by a spectrum of 10 mutations.

The clinical spectrum of 3-MGA-I in children is heterogeneous, varying from asymptomatic individuals to mild neurological impairment, speech delay, quadriplegia, dystonia, choreoathetoid movements, severe encephalopathy, psychomotor retardation, basal ganglia involvement. Early dietary treatment with leucine restriction and carnitine supplementation may be effective in improving neurological state in pediatric patients with 3-MGA-I.

We presented a girl with 3-MGA-I due to novel AUH gene mutation (homozygous variant c.330 + 5G > A) and confirmed by almost undetectable 3-MGH-enzyme activity, who initially presented with central precocious puberty at an early age of 4.5 years.

Precocious puberty might be associated with the 3-MGA-I, as is reported previously in some other metabolic disorders that result in pathologic accumulation of metabolites or toxic brain damage. Therapy with GnRH agonist triptorelin effectively arrested pubertal development.

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Girl with 3-MGA-I presented with central precocious puberty.

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Novel AUH gene mutation and almost undetectable 3-MGH-enzyme activity were detected.

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GnRH agonist triptorelin effectively arrested pubertal development.

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Precocious puberty is reported in some other metabolic disorders.

Carotid Intima-Media Thickness in Healthy Children and Adolescents: Normative Data and Systematic Literature Review

Objectives: Early identification of children at risk of atherosclerosis is of paramount importance for implementing primary preventive measures addressing vascular health. Carotid intima-media thickness (cIMT) is a non-invasive biomarker of atherosclerosis. Semiautomatic radiofrequency-based software-guided technique quality intima-media thickness (RF-QIMT) was used to determine cIMT normative values in a healthy cohort of Caucasian children aged 6 to 18 years.

Study design: In a cross-sectional study, data on age, chronic illness, medication use, and pubertal status was acquired by a questioner. Anthropometric and blood pressure measurements were performed by standardized methods and trained medical personnel. cIMT of the right common carotid artery far wall (1 centimeter proximal to bifurcation) was determined using a multifrequency (3–13 MHz) electronic linear array transducer SL1543, a portable ultrasound device (MyLab Gamma Esaote, Genoa, Italy), and RF-QIMT software. A systematic review of the published normal cIMT in children was done using PRISMA methodology, and identified normative values were compared to those obtained in the presented study.

Results: 1137 non-obese normotensive children (males: n = 512; mean age 12.04 ± 3.52 years, females: n = 625, mean age 12.98 ± 3.83 years) were included. Gender-, age-, and height-specific mean cIMT percentile tables, percentile charts, and LMS tables for the RF-QIMT method were provided. They were comparable to the previously published data on mean cIMT gained by other validated ultrasound imaging techniques. cIMT increased with age, height, hip circumference, and BMI and was higher in males.

Conclusions: Gender-, age-, and height-specific normative cIMT values, using the semiautomatic software-guided RF-QIMT technique, in children aged 6 to 18 years were developed and validated in respect to the previously published pediatric normative cIMT data. It is suggested that the investigated method could be used for the estimation of atherosclerotic risk in children, especially in epidemiological studies.

Improvement of pneumococcal pneumonia diagnostics by the use of rt-PCR on plasma and respiratory samples

BACKGROUND

The aim of the study was to assess the performance of a real-time polymerase chain reaction (rt-PCR) assay on plasma and respiratory samples for the diagnosis of pneumococcal pneumonia.

METHODS

Three hundred and forty patients (160 children and 180 adults) with community-acquired pneumonia were included prospectively from January 2011 to May 2012. Blood samples were obtained simultaneously for culture and rt-PCR targeting the lytA gene. Respiratory samples were also obtained: nasopharyngeal swab in nearly all patients and sputum or tracheal aspirate when available.

RESULTS

Streptococcus pneumoniae was detected in 222 (65%) of 340 patients: 143 (89%) children and 79 (44%) adults. Pneumonia was assigned as definite pneumococcal in 96 (28.2%) of 340 patients, according to S. pneumoniae detected in blood: in 54 (33.8%) children - by rt-PCR in 51 (31.9%) and by culture in 5 (3.1%); and in 42 (23.3%) adults - by rt-PCR in 41 (22.8%) and by culture in 12 (6.7%). Pneumonia was considered as probably pneumococcal in 19 (10.6%) adults according to S. pneumoniae detected in sputum/tracheal aspirate, by rt-PCR in 19 and by culture in 5. In 18 adults and 89 children with S. pneumoniae detected only in the nasopharynx, pneumonia was considered as possibly pneumococcal; however it should be noted that nasopharyngeal colonization with S. pneumoniae is also common in children with other aetiologies of pneumonia.

CONCLUSIONS

rt-PCR on plasma and other samples performed significantly better than culture for the detection of pneumococcal pneumonia (p < 0.0005) in children and adults.