Odimet®: A Pioneering Tele-Health Tool to Empower Dietary Treatment and the Acute Management of Inborn Errors of Metabolism-An Assessment of Its Effectiveness during the COVID Pandemic.

Strict adherence to a diet is an essential pillar of long-term treatment for many inborn errors of metabolism (IEMs). Tools that educate patients about dietary management can positively condition adherence and prevent morbidity. We designed a free online dietary calculation program (Odimet®, version 2.1.) for IEMs patients in 2008, updated in 2022, that provides detailed information on the content of amino acids, protein, lipids, carbohydrates, vitamins and minerals in >3000 food products, including specific medical foods for IEM. We analyzed the statistics on visits to Odimet® to evaluate its usefulness for long-term dietary management during a 5-year period focusing on three periods: pre-pandemic (15 March 2018-14 March 2020); pandemic 1 (15 March 2020-14 March 2021); and pandemic 2 period (15 March 2021-15 March 2023), in 120 patients with the following distribution: 84 patients with phenylketonuria (PKU); 12 with maple syrup urine disease (MSUD); 11 with urea cycle disorders (UCDs); and 13 with classical galactosemia. The evolutionary levels of their specific metabolic markers were evaluated, showing that globally, both pediatric and adult patients maintain a good metabolic control, even during a pandemic (median levels of phenylalanine in pediatric PKU patients 213.4 µmol/L and 482.3 µmol/L in adults; of leucine in MSUD patients: 144.2 µmol/L; of glutamine in UCDs: 726.8 µmol/L; and of galactose 1-phosphate levels in galactosemia: 0.08 µmol/L). The proportion of patients using Odimet® ranges from 78-100%. An increase in the number of diets being calculated was observed during COVID-19 pandemic. Currently, 14,825 products have been introduced (3094 from the general database, and 11,731 added by users to their own profiles). In 2023 63 emergency dietary adjustments in the studied intoxication-type pathologies were calculated in Odimet®. Our results suggest that its regular use contributes to maintaining metabolic stability in IEMs patients, allowing them to adapt their menus to their lifestyle, and represents a powerful complementary tele-health tool which can be used to perform remote real-time dietary follow-up.

Classical Hereditary galactosemia: findings in patients and animal models.

Classic galactosemia is a rare inborn error of metabolism that affects the metabolism of galactose, a sugar derived from milk and derivates. Classic galactosemia is caused by variants of the GALT gene, which lead to absent or misfolded forms of the ubiquitously present galactose-1-phosphate uridylyltransferase enzyme (GALT) driving galactose metabolites to accumulate, damaging cells from neurons to hepatocytes. The disease has different prevalence around the world due to different allele frequencies among populations and its symptoms range from cognitive and psychomotor impairment to hepatic, ophthalmological, and bone structural damage. The practice of newborn screening still varies among countries, dairy restriction treatment is a consensus despite advances in preclinical treatment strategies. Recent clinical studies in Duarte variant suggest dairy restriction could be reconsidered in these cases. Despite noteworthy advances in the classic galactosemia understanding, preclinical trials are still crucial to fully understand the pathophysiology of the disease and help propose new treatments. This review aims to report a comprehensive analysis of past studies and state of art research on galactosemia screening, its clinical and preclinical trials, and treatments with the goal of shedding light on this complex and multisystemic innate error of the metabolism.

Classic Galactosemia: Clinical and Computational Characterization of a Novel GALT Missense Variant (p.A303D) and a Literature Review.

Classic galactosemia is an autosomal recessive inherited liver disorder of carbohydrate metabolism caused by deficient activity of galactose-1-phosphate uridylyltransferase (GALT). While a galactose-restricted diet is lifesaving, most patients still develop long-term complications. In this study, we report on a two-week-old female patient who is a compound heterozygote for a known pathogenic variant (p.K285N) and a novel missense variant (p.A303D) in the GALT gene. Segregation analysis showed that the patient inherited the p.K285N pathogenic variant from her father and the p.A303D variant from her mother. A bioinformatics analysis to predict the impact of the p.A303D missense variant on the structure and stability of the GALT protein revealed that it may be pathogenic. Based on this finding, we performed a literature review of all GALT missense variants identified in homozygous and compound heterozygous galactosemia patients carrying the p.K285N pathogenic variant to explore their molecular effects on the clinical phenotype of the disease. Our analysis revealed that these missense variants are responsible for a wide range of molecular defects. This study expands the clinical and mutational spectrum in classic galactosemia and reinforces the importance of understanding the molecular consequences of genetic variants to incorporate genetic analysis into clinical care.

Long-term complications in classic galactosemia are not progressive.

Classic galactosemia (CG) is a potentially lethal genetic disorder that results from profound deficiency of galactose-1-P uridylyltransferase. Despite early detection and life-long dietary restriction of galactose, which is the current standard of care, many patients with CG grow to experience a range of long-term developmental complications that can include difficulties with speech/voice/language, cognitive, motor, and psychosocial outcomes, among other problems. That these complications are common in CG is well-documented, but whether they are also progressive has been a point of controversy for decades. Here, we addressed the question of whether long-term outcomes in CG are progressive by analyzing a robust data set in each of 4 ways. First, we compared cross-sectional Vineland-3 Adaptive Behavior Scales scores for 101 cases and 65 unaffected sibling controls and found no evidence of consistently declining scores with age. Second, we analyzed longitudinal Vineland-3 subdomain scores for 45 cases and 34 controls to see if individual participants demonstrated developmental gains (positive slope) or losses (negative slope) over time. The changes in most growth scale value (GSV) scores, which are not normed, were positive for both cases and controls <10y, and either positive or near zero for participants ≥10y. In contrast, the slopes of most v-Scale scores, which are normed, were negative for many cases <10y, indicating that these children, while gaining milestones, were gaining them at a slower pace than their counterparts in the reference population. Third, we analyzed medical records from 76 cases, assigning ordinal scores for complications and gathering the quantitative results of relevant formal assessments where available. Both cross-sectional and longitudinal analyses of both ordinal and formal assessment scores confirmed that outcomes were mostly stable, albeit with some ups and downs in isolated cases. Finally, we analyzed data collected via custom family-response surveys from 124 cases and 67 controls regarding each participant's perceived symptom severity over time. Among cases, the percentages of respondents reporting worsening symptoms over time for speech, cognitive, motor, and psychosocial outcomes were 0.8%, 6.6%, 5.2%, and 9.8%, respectively. Among controls, the corresponding percentages were 0.0%, 1.5%, 1.5%, and 6.5%, respectively. These results provide compelling evidence that long-term developmental complications are not progressive for a majority of patients with CG.

Diagnostic yield of workups ordered by pediatric ophthalmologists for bilateral pediatric cataracts at a tertiary pediatric hospital in the United States.

BACKGROUND: Children with unexplained bilateral cataracts routinely undergo testing for genetic, infectious, and metabolic etiologies. We evaluated the diagnostic yield of various tests ordered by pediatric ophthalmologists to evaluate bilateral cataracts in children at a single institution. METHODS: We retrospectively identified all children with bilateral unexplained cataracts who underwent cataract surgery by a pediatric ophthalmologist at Children's Hospital Colorado from 2006 to 2022. We reviewed the results of genetic, infectious, and metabolic testing ordered by pediatric ophthalmologists to evaluate the cataracts in these children. RESULTS: A total of 43 children met inclusion criteria. Of these, 34 (79%) had genetic testing, 34 (79%) had infectious disease testing, 33 (77%) had galactosemia testing, and 17 (40%) had urine-reducing substances testing performed during their cataract evaluation. Of the genetic tests ordered, 17 (50%) revealed a pathogenic mutation associated with cataracts. Twenty-three (68%) patients were IgG-positive for a TORCH infection, but no child was found to be positive on confirmatory testing. Of the galactosemia and URS tests ordered, 3 tests (9%) and 1 (6%) test were initially found to be abnormal, respectively, but confirmatory testing and clinical judgment ruled out metabolic disease in each case. CONCLUSIONS: Genetic testing should be strongly considered in all cases of unexplained bilateral pediatric cataracts. Metabolic and infectious testing is best considered only after consultation with the child's pediatrician, guided by the patient's clinical context and the availability of genetic testing.

Understanding the patient experience of Classic Galactosemia in pediatric and adult patients: increased disease burden, challenges with daily living, and how they evolve over time.

BACKGROUND: Classic Galactosemia (CG) is a rare, autosomal recessive condition. Newborn screening and a timely galactose-restricted diet can resolve acute symptoms and decrease fatalities, but significant chronic, progressive morbidities remain and significantly impact daily life. The objective of this study was to better understand the burden of disease in children and adults with CGs and describe how morbidities evolve over time. METHODS: A total of 49 individuals with CG from the United States (US) were included in the qualitative surveys (13 adults [9 self-reported] and 36 pediatric patients). Fifteen follow-up interviews were conducted with 5 adults and 10 caregivers, discussing 17 individuals with CG overall (2 caregivers each discussed 2 children). RESULTS: Qualitative survey and interview data demonstrated the substantial burden of CG. Difficulties in a wide range of functions were experienced, which included: speech articulation; language and communication; cognition, memory and learning; emotions; and social interactions. Most difficulties appeared in childhood and persisted or worsened with age. Most adults did not live independently. Others lived semi-independently and experienced many daily challenges and required support. Caregivers also described the burden of caring for someone with CG and spoke about the impact this has on their day-to-day life, work, and relationships. CONCLUSIONS: These findings demonstrate the pronounced and persistent burden of disease encountered by individuals with CG, and that the condition has a significant impact on the quality of life of caregivers.

Grip strength in patients with galactosemia and in a galactose-1-phosphate uridylyltransferase (GALT)-null rat model.

Classic galactosemia (CG) and clinical variant galactosemia (CVG) are allelic inborn errors of metabolism that result from profound deficiency, and near-profound deficiency, respectively, of galactose-1-P uridylyltransferase (GALT). Despite early detection and lifelong dietary restriction of galactose, which is the current standard of care, most patients with CG/CVG grow to experience a range of long-term developmental and other complications. One of the less well-understood complications of CG/CVG is decreased hand grip strength, as reported by Potter et al. (2013). Here, we confirm this phenotype in an independent cohort of 36 cases (4-18 years) and 19 controls (4-17 years), and further demonstrate that the grip strength deficit observed in cases may be secondary to growth delay. Specifically, we found that when grip strength of cases and controls in a new cohort recruited in 2022 was plotted by weight, rather than age, the difference between cases and controls for both sexes disappeared. Reanalyzing data from the original 2013 cohort, we found that differences in weight accounted for grip strength differences between cases and controls in girls and young women, but not in boys and young men. Finally, we tested whether a GALT-null rat model of CG also showed a grip strength deficit-it did-and again the difference between GALT-null and wild-type rats associated with differences in body mass. Combined, these results confirm that GALT deficiency is associated with a grip strength deficit in both young patients with CG/CVG and GALT-null rats, and further demonstrate that this phenotype may be secondary to growth delay, and therefore not evidence of a muscle abnormality.

Development, optimization and validation of LC-MS/MS method for the determination of DBS GALT enzyme activity.

Galactosemia is a carbohydrate metabolism disorder often caused by galactose-1-phosphate uridyl transferase (GALT) deficiency. Detecting GALT deficiency involves measuring intra-erythrocyte enzyme activity. We aimed to create a robust liquid chromatography-mass spectrometry (LC-MS/MS) method to assess GALT activity in dried blood spot (DBS) samples. We validated this method and compared it to the fluorometric approach. We investigated the impact of K2EDTA and lithium heparin tubes on enzyme activity to identify the best sample collection tube. We also assessed the reaction-stopping method. The developed approach employed [13C6]-galactose-1-phosphate as a substrate and UDP-N-acetylglycosamine as an internal standard (IS). The mean ± SD value for GALT activity of DBS samples was determined as 6.37 ± 1.96 µmol/gHb/hour. The linear range was 0.4-50 µM (2.4-310% of normal) in the DBS method. The % coefficient of variation (%CV) values were less than 15 for intra-day and inter-day repeatability studies. Over 90% recovery was achieved in recovery studies, and no ion suppression from matrix was detected. DBS samples were quite stable for 31 days under different storage conditions. Enzyme activity results reported as <3.5 U/g Hb by fluorometric method, were quantitatively determined for even very low concentrations by LC-MS/MS method.

The challenges of classical galactosemia: HRQoL in pediatric and adult patients.

BACKGROUND: Classical galactosemia (CG), an inborn error of galactose metabolism, results in long-term complications including cognitive impairment and movement disorders, despite early diagnosis and dietary treatment. Two decades ago, lower motor-, cognitive- and social health related quality of life (HRQoL) was demonstrated in pediatric and adult patients. Since then, the diet has been relaxed, newborn screening was implemented and new international guidelines resulted in major changes in follow-up. The aim of this study was to assess HRQoL of CG by means of online self- and/or proxy-HRQoL-questionnaires focusing on the main areas of concern of CG (i.e. anxiety, depression, cognition, fatigue, social- and upper extremity function) within the patient-reported outcomes measurement information system (PROMIS®) and generic HRQoL-questionnaires (TAPQOL, TACQOL, TAAQOL). RESULTS: Data of 61 Dutch patients (aged 1-52 years) were collected and compared to available Dutch or US reference populations. On the PROMIS-questionnaires, children reported more fatigue (P = 0.044), lower function in upper extremities (P = 0.021), more cognitive difficulties (P = 0.055, d = 0.56) and higher anxiety (P = 0.063, d = 0.52) than reference children although the latter findings remained non-significant. Parents of CG patients reported lower quality of peer relationships of their children (P < 0.001). Both children and parents reported lower cognitive functioning (P = 0.005, P = 0.010) on the TACQOL. Adults reported on PROMIS domains lower cognitive functioning (P = 0.030), higher anxiety (P = 0.004) and more fatigue (P = 0.026). Cognitive difficulties were reported on the TAAQOL by adults (P < 0.001), as well as physical-, sleeping and social difficulties. CONCLUSIONS: CG remains to impact the HRQoL of pediatric and adult patients negatively on several domains including cognition, anxiety, motor function and fatigue. A lower social health was mainly reported by parents, and not by patients themselves. The Covid-19 pandemic might have amplified the results on anxiety although higher levels of anxiety fit pre-pandemic findings. The reported fatigue is a new finding in CG. Because the effect of lockdown fatigue could not be eliminated and fatigue is a frequent finding in patients with chronic disorders, future studies are warranted. Clinicians and researchers should be attentive to both pediatric and adult patients, and the age-dependent difficulties they might encounter.

[Clinical characteristics and genetic analysis of a child with Galactosemia due to compound heterozygous variants of GALT gene].

OBJECTIVE: To explore the clinical features and genetic basis of a child with Galactosemia. METHODS: A child who had presented at the Children's Hospital Affiliated to Zhengzhou University on November 20, 2019 was selected as the study subject. Clinical data of the child was collected. Whole exome sequencing was carried out for the child. Candidate variants were validated by Sanger sequencing. RESULTS: Clinical manifestations of the child have included anemia, feeding difficulty, jaundice, hypomyotonia, abnormal liver function and coagulation abnormality. Tandem mass spectrometry showed increased citrulline, methionine, ornithine and tyrosine. Urine organic acid analysis showed increased phenyllactic acid, 4-hydroxyphenylacetic acid, 4-hydroxyphenyllactic acid, 4-hydroxyphenylpyruvate and N-acetyltyrosine. Genetic testing revealed that the child has harbored compound heterozygous variants of the GALT gene, namely c.627T>A (p.Y209*) and c.370G>C (p.G124R), which were respectively inherited from her healthy parents. Among these, c.627T>A (p.Y209*) was known as a likely pathogenic variant, while c.370G>C (p. G124R) was unreported previously and also predicted as a likely pathogenic variant(PM1+PM2_Supporting+PP3_Moderate+PPR). CONCLUSION: Above discovery has expanded the spectrum of the GALT gene variants underlying Galactosemia. Patients with thrombocytopenia, feeding difficulties, jaundice, abnormal liver function and coagulation abnormality without obvious causes should be analyzed by screening of metabolic diseases in combination with genetic testing.

Endocrine Disorders in a Newborn with Heterozygous Galactosemia, Down Syndrome and Complex Cardiac Malformation: Case Report.

Down syndrome is the most common chromosomal abnormality diagnosed in newborn babies. Infants with Down syndrome have characteristic dysmorphic features and can have neuropsychiatric disorders, cardiovascular diseases, gastrointestinal abnormalities, eye problems, hearing loss, endocrine and hematologic disorders, and many other health issues. We present the case of a newborn with Down syndrome. The infant was a female, born at term through c-section. She was diagnosed before birth with a complex congenital malformation. In the first few days of life, the newborn was stable. In her 10th day of life, she started to show respiratory distress, persistent respiratory acidosis, and persistent severe hyponatremia, and required intubation and mechanical ventilation. Due to her rapid deterioration our team decided to do a screening for metabolic disorders. The screening was positive for heterozygous Duarte variant galactosemia. Further testing on possible metabolic and endocrinologic issues that can be associated with Down syndrome was performed, leading to hypoaldosteronism and hypothyroidism diagnoses. The case was challenging for our team because the infant also had multiple metabolic and hormonal deficiencies. Newborns with Down syndrome often require a multidisciplinary team, as besides congenital cardiac malformations they can have metabolic and hormonal deficiencies that can negatively impact their short- and long-term prognosis.

Caregivers' nutrition-related knowledge, perceptions, practices and barriers regarding the therapeutic diet for classical galactosaemia.

BACKGROUND: Classical galactosaemia is a life-threatening disorder of carbohydrate metabolism, and the primary treatment is a lifelong galactose-restricted diet commenced in infancy. Adherence to restrictive diets can be burdensome for patients and their families; however, little is known about the impact on caregivers. AIM: This study aims to determine the nutrition-related knowledge, perceptions, practices, and barriers of caregivers related to the therapeutic diet for classical galactosaemia. METHODS: An online survey was conducted among 98 eligible members of the Galactosaemia Support Group using a novel questionnaire. Descriptive and inferential analyses were performed using Microsoft Excel 2021 and Stata/MP (version 17.0), respectively. Forty-three caregivers participated in the study. RESULTS AND CONCLUSION: Of those who participated, 98% had high levels of dietary knowledge. Caregivers' knowledge scores ( x ¯ $\bar{{\rm{x}}}$ = 17.9, standard deviation [SD] = 1.7) were positively correlated with educational level (r = 0.383, p = 0.013). High attitudinal scores ( x ¯ $\bar{{\rm{x}}}$ = 32.5, SD = 5.5) obtained by most caregivers (65%) revealed an overall positive attitude towards the galactosaemia diet. Negative perceptions of being unable to feed their child breast milk (49%) were apparent, and this perception was positively correlated with caregivers' intention to feed their child breast milk (r = 0.450, p = 0.003). Caregivers' concerns about the safety of their child in social settings (79%) and feeling that their child was excluded in social settings (49%) were clear barriers. A multidisciplinary approach to galactosaemia management is warranted, with healthcare interventions focusing on addressing caregivers' negative perceptions and barriers related to the diet to enable tailored support and facilitate lifelong compliance.

Lactose and Galactose Content in Spanish Cheeses: Usefulness in the Dietary Treatment of Patients with Galactosaemia.

In galactosaemia, a strict galactose-free diet is necessary to prevent or resolve acute symptoms in infants. However, because the body produces up to 10 times more galactose than is found in a galactose-restricted diet, excessively restrictive diets should be avoided in children and adults to prevent nutritional deficiencies. Since cheese is a nutritional source of the calcium necessary for bone health, the latest international guidelines on the management of classical galactosaemia (2017) allow the consumption of cured cheeses with less than 25 mg of galactose/100 g and recommend that each country verifies the adequacy of the cheeses, since most mature cheeses do not always have a lower galactose content. In total, 32 cheese samples were purchased (19 Spanish and 13 international cheeses), and their lactose and galactose contents were analysed using ion chromatography with pulsed amperometric detection (IC-PAD). Five Spanish cheeses contained less than 25 mg of galactose/100 g: García Baquero semi-cured cheese; Hacendado, Gran Reserva and Mahón cured cheeses; and García Baquero Reserva 12-month cured cheese. In addition, eight international cheeses were confirmed as suitable: Comté, Gouda, Gruyere, Maasdam, Parmigiano, Edam, Emmental, and some samples of Cheddar. In addition to the well-known low-galactose Swiss and Dutch cheeses, according to the current results, five Spanish cheeses can be safely consumed. The greater availability of types of cheese favours better bone health in patients with galactosaemia.

GALE variants associated with syndromic manifestations, macrothrombocytopenia, bleeding, and platelet dysfunction.

GALE gene encodes the uridine diphosphate [UDP]-galactose-4-epimerase, which catalyzes the bidirectional interconversion of UDP-glucose to UDP-galactose, and UDP-N-acetyl-glucosamine to UDP-N-acetyl-galactosamine. In that way, GALE balances, through reversible epimerization, the pool of four sugars that are essential during the biosynthesis of glycoproteins and glycolipids. GALE-related disorder presents an autosomal recessive inheritance pattern, and it is commonly associated with galactosemia. Peripheral galactosemia generally associates with non-generalized forms or even asymptomatic presentations, while classical galactosemia may be related to complications such as learning difficulties, developmental delay, cardiac failure, or dysmorphic features. Recently, GALE variants have been related to severe thrombocytopenia, pancytopenia, and in one patient, to myelodysplastic syndrome.

What is the context? GALE gene encodes for the UDP-Galactose 4-Epimerase, an enzyme involved in the Leloir pathway of galactose catabolism and protein glycosylation.Homozygous or compound heterozygous GALE variants associate with the disorder known as galactosemia type III.Three types of galactosemia can be distinguished: the peripheral, the intermediate, and the generalized form, which associate with different clinical symptoms and GALE genetic variants.Peripheral form is considered benign, while the intermediate and the generalized form is associated with severe and syndromic manifestations, including learning difficulties, delayed growth, sensorineural hearing loss, and early-onset cataracts, among others.What is new? In the last few years, GALE variants have been linked to hematological manifestations, such as anemia, febrile neutropenia, and severe thrombocytopenia.To date, the only GALE variants described in patients presenting hematological disorders are GALE p.Arg51Trp, p.Lys78ValfsX32, p.Val128Met, p.Thr150Met, p.Leu223Pro, and p.Gly237Asp.The thrombocytopenia observed in GALE patients is associated with reduced GPIbα and ß1 integrin glycosylation and externalization to the megakaryocyte and platelet surface, disrupting the actin cytoskeleton remodeling.What is the impact? GALE is an essential protein for the correct megakaryocyte and platelet glycosylation.

Racial and ethnic diversity of classic and clinical variant galactosemia in the United States.

Classic and clinical variant galactosemia (CG/CVG) are allelic, autosomal recessive disorders that result from deficiency of galactose-1-P uridylyltransferase (GALT). CG/CVG has been reported globally among patients of diverse ancestries, but most large studies of outcomes have included, almost exclusively, patients categorized as White or Caucasian. As a first step to explore whether the cohorts studied are representative of the CG/CVG population at large, we sought to define the racial and ethnic makeup of CG/CVG newborns in a diverse population with essentially universal newborn screening (NBS) for galactosemia: the United States (US). First, we estimated the predicted racial and ethnic distribution of CG/CVG by combining the reported demographics of US newborns from 2016 to 2018 with predicted homozygosity or compound heterozygosity of pathogenic, or likely pathogenic, GALT alleles from the relevant ancestral groups. Incorporating some simplifying assumptions, we predicted that of US newborns diagnosed with CG/CVG, 65% should be White (non-Hispanic), 23% should be Black (non-Hispanic), 10% should be Hispanic, and 2% should be Asian (non-Hispanic). Next, we calculated the observed racial and ethnic distribution of US newborns diagnosed with CG/CVG using available de-identified data from state NBS programs from 2016 to 2018. Of the 235 newborns in this cohort, 41 were categorized as other or unknown. Of the remaining 194, 66% were White (non-Hispanic or ethnicity unknown), 16% were Black (non-Hispanic or ethnicity unknown),15% were Hispanic, and 2% were Asian (non-Hispanic or ethnicity unknown). This observed distribution was statistically indistinguishable from the predicted distribution. To the limits of our study, these data confirm the racial and ethnic diversity of newborns with CG/CVG in the US, demonstrate an approach for estimating CG/CVG racial and ethnic diversity in other populations, and raise the troubling possibility that current understanding of long-term outcomes in CG/CVG may be skewed by ascertainment bias of the cohorts studied.

Assessment of Dietary Intake of Iodine and Risk of Iodine Deficiency in Children with Classical Galactosaemia on Dietary Treatment.

Iodine is an essential mineral required for the synthesis of thyroid hormones. Iodine plays a critical role in growth and neurocognitive development. Classical galactosaemia is a disorder resulting from an inborn error in galactose metabolism. Its current management consists of life-long lactose and galactose dietary restriction. This study estimated dietary intakes of iodine in infants and children with classical galactosaemia in the Republic of Ireland. The diets of 43 participants (aged 7 months-18 years) with classical galactosaemia were assessed for iodine intake using an iodine-specific food frequency questionnaire. Intakes were compared to the European Food Safety Authority (EFSA) dietary recommendations for iodine intake. The potential role of iodine fortification of dairy alternative products was also examined. There were no significant differences observed between sex, ethnicity and parental education and meeting dietary iodine recommendations. Differences, however, were seen between age groups, causing the p value to approach statistical significance (p = 0.06). Infants consuming infant formula were likely to meet iodine recommendations. However, over half (53%) of children aged 1-18 years had average intakes below the recommendations for age. For these children, consumption of iodine-fortified dairy alternative milk was the leading source of iodine in the diets, followed by fish/shellfish and eggs. An assessment of iodine intake should be undertaken during dietetic reviews for those with classical galactosaemia. Mandatory iodine fortification of all dairy alternative products would result in 92% of the total population cohort meeting iodine recommendations based on their current consumption.

An Approach for Evaluating Potential Screening Thresholds Using Biomarker Population Distribution and Analytical Imprecision.

BACKGROUND: A common approach in laboratory medicine is to use a simple but sensitive test to screen samples to identify those that require additional investigation with a more complex and informative method. Selection of screening thresholds can be guided by biomarker distribution in the tested population and the analytical imprecision of the method. METHODS: A simulation using joint probabilities derived from the population distribution for galactose-1-phosphate uridylyltransferase (GALT) activity and the analytical imprecision for the GALT assay was used to estimate the number of samples that would require repeat analysis and the number of samples with possibly false-negative screening determinations due to analytical imprecision. RESULTS: In the case of GALT activity, screening a conservative initial threshold 6 standard deviations from the confirmation threshold can essentially eliminate the chance of a false-negative screening determination due to analytical imprecision. The trade-off is a greater number of samples requiring follow-up testing (n = 222, equivalent to 0.15% of samples annually). CONCLUSIONS: Selection of thresholds in a screening algorithm is informed by estimates of the number of samples that would require repeat testing and the number that could be false negative due to analytical imprecision.

Comprehensive analysis of non-synonymous missense SNPs of human galactose mutarotase (GALM) gene: an integrated computational approach.

Missense Non-synonymous single nucleotide polymorphisms (nsSNPs) of Galactose Mutarotase (GALM) are associated with the Novel type of Galactosemia (Galactosemia type 4) together with symptoms such as high blood galactose levels and eye cataracts. The objective of the present study was to identify deleterious nsSNPs of GALM recorded on the dbSNP database through comprehensive insilico analysis. Among the 319 missense nsSNPs reported, various insilco tools predicted R78S, R82G, A163E, P210S, Y281C, E307G and F339C as the most deleterious mutations. Structural analysis, PTM analysis and molecular dynamics simulations (MDS) were carried out to understand the effect of these mutations on the structural and physicochemical properties of the GALM protein. The residues R82G and E307G were found to be part of the binding site that resulted in decreased surface accessibility. Replacing the charged wild-type residue with a neutral mutant type affected its substrate binding. All 7 mutations were found to increase the rigidity of the protein structure, which is unfavorable during ligand binding. The mutation F339E made the protein structure more rigid than all the other mutations. Y281 is a phosphorylated site, and therefore, less significant structural changes were observed when compared to other mutations; however, it may have significant differences in the usual functioning of the protein. In summary, the structural and functional analysis of missense SNPs of GALM is important to reduce the number of potential mutations to be evaluated in vitro to understand the association with some genetic diseases.Communicated by Ramaswamy H. Sarma.