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.

Neonatal classic galactosemia-diagnosis, clinical profile and molecular characteristics in unscreened Turkish population.

BACKGROUND: Classic galactosemia (CG) is a rare hereditary disease that can cause serious morbidity and death if it is not diagnosed and treated in early periods of life. Clinical findings usually occur in the neonatal period after the neonate is fed with milk that contains galactose. Most patients are presented with jaundice, hepatomegaly, hypoglycemia and cataracts. OBJECTIVE: We aimed to document the clinical, molecular characteristics, regional estimated incidence and time of diagnosis in newborn with CG. MATERIALS AND METHOD: The data of 63 newborn with CG who were diagnosed and followed up between January 2011 and January 2018 were analyzed retrospectively. RESULTS: During the study period, 63 (33 boys and 30 girls) newborns were diagnosed with CG. The median gestational age was 39 weeks (33-42). Major presenting symptoms were jaundice 90.5% and cataract 41.2%. The mean age at first symptom was 12 ± 7.4 days while the mean age at diagnosis was 18.9 ± 10.6 days. Nearly half of the patients (55.5%) were diagnosed later than the postnatal 15th day. Genetic analysis was performed on 56 patients and homozygous Q188R mutation was found in 92.8%. There were signs of sepsis in 33.3% of the cases. Six patients died due to sepsis. There was consanguinity in 84.1% of the parents and regional estimated incidence was calculated as 1 in 6103 live births. CONCLUSION: Q188R mutation was found in 92.8% of our cases. The regional estimated incidence was found as 1 in 6103 live births. Our study strongly supports that galactosemia should be included in the national newborn screening program.

Galactokinase deficiency: lessons from the GalNet registry.

PURPOSE: Galactokinase (GALK1) deficiency is a rare hereditary galactose metabolism disorder. Beyond cataract, the phenotypic spectrum is questionable. Data from affected patients included in the Galactosemias Network registry were collected to better characterize the phenotype. METHODS: Observational study collecting medical data of 53 not previously reported GALK1 deficient patients from 17 centers in 11 countries from December 2014 to April 2020. RESULTS: Neonatal or childhood cataract was reported in 15 and 4 patients respectively. The occurrence of neonatal hypoglycemia and infection were comparable with the general population, whereas bleeding diathesis (8.1% versus 2.17-5.9%) and encephalopathy (3.9% versus 0.3%) were reported more often. Elevated transaminases were seen in 25.5%. Cognitive delay was reported in 5 patients. Urinary galactitol was elevated in all patients at diagnosis; five showed unexpected Gal-1-P increase. Most patients showed enzyme activities ≤1%. Eleven different genotypes were described, including six unpublished variants. The majority was homozygous for NM_000154.1:c.82C>A (p.Pro28Thr). Thirty-five patients were diagnosed following newborn screening, which was clearly beneficial. CONCLUSION: The phenotype of GALK1 deficiency may include neonatal elevation of transaminases, bleeding diathesis, and encephalopathy in addition to cataract. Potential complications beyond the neonatal period are not systematically surveyed and a better delineation is needed.

NGS-based expanded carrier screening for genetic disorders in North Indian population reveals unexpected results - a pilot study.

BACKGROUND: To determine the carrier frequency and pathogenic variants of common genetic disorders in the north Indian population by using next generation sequencing (NGS). METHODS: After pre-test counselling, 200 unrelated individuals (including 88 couples) were screened for pathogenic variants in 88 genes by NGS technology. The variants were classified as per American College of Medical Genetics criteria. Pathogenic and likely pathogenic variants were subjected to thorough literature-based curation in addition to the regular filters. Variants of unknown significance were not reported. Individuals were counselled explaining the implications of the results, and cascade screening was advised when necessary. RESULTS: Of the 200 participants, 52 (26%) were found to be carrier of one or more disorders. Twelve individuals were identified to be carriers for congenital deafness, giving a carrier frequency of one in 17 for one of the four genes tested (SLC26A4, GJB2, TMPRSS3 and TMC1 in decreasing order). Nine individuals were observed to be carriers for cystic fibrosis, with a frequency of one in 22. Three individuals were detected to be carriers for Pompe disease (frequency one in 67). None of the 88 couples screened were found to be carriers for the same disorder. The pathogenic variants observed in many disorders (such as deafness, cystic fibrosis, Pompe disease, Canavan disease, primary hyperoxaluria, junctional epidermolysis bullosa, galactosemia, medium chain acyl CoA deficiency etc.) were different from those commonly observed in the West. CONCLUSION: A higher carrier frequency for genetic deafness, cystic fibrosis and Pompe disease was unexpected, and contrary to the generally held view about their prevalence in Asian Indians. In spite of the small sample size, this study would suggest that population-based carrier screening panels for India would differ from those in the West, and need to be selected with due care. Testing should comprise the study of all the coding exons with its boundaries in the genes through NGS, as all the variants are not well characterized. Only study of entire coding regions in the genes will detect carriers with adequate efficiency, in order to reduce the burden of genetic disorders in India and other resource poor countries.

How a baby with classic galactosemia was nearly missed: When the test succeeds but system fails.

Newborn screening (NBS) is a well-established state-run public health program which has targeted the early identification of treatable diseases like classic galactosemia (CG) for over a decade. We describe the case of a symptomatic newborn with CG and an abnormal screen report, including positive DNA-based test, who still managed to fall through the cracks in a sub-optimally functioning NBS program, despite decades of screening experience. While much attention is paid to testing technology, this case illustrates basic minimum requirements a newborn screening program must fulfill to reliably identify and treat all affected individuals including minimum reporting requirements, case surveillance and a dedicated short-term follow-up program. In newborn screening, success is systematic.

Newborn Screening for Five Conditions in a Tertiary Care Government Hospital in Bengaluru, South India-Three Years Experience.

PURPOSE: Newborn screening is the need of the hour in a developing country like India as there is paucity of data from studies conducted in government hospitals with large sample size. The purpose of the study is to estimate incidence rate and recall rates for five conditions screened in the neonatal period namely congenital hypothyroidism, congenital adrenal hyperplasia, glucose-6-phosphate dehydrogenase (G6PD) deficiency, galactosemia and phenyl ketonuria (PKU). METHODS: The study was conducted at VaniVilas Hospital attached to Bangalore Medical College and Research Institute. A retrospective analysis of the results of newborn screening programme during a 3-year period between January 2016 and December 2018 was done. There were 47 623 livebirths during this period out of which 41 027 babies were screened (coverage-86% of total livebirths). Heelprick samples after 48 h of life and prior to discharge were analysed by quantitative assessment. Neonates having positive screening results were recalled by telephonic call for repeat screening and confirmatory tests. RESULTS: G6PD deficiency was the most common disorder with an incidence of 1:414, followed by congenital hypothyroidism and Congenital Adrenal Hyperplasia with an incidence of 1:2735 and 1:4102, respectively. Galactosemia and PKU were found to be rare in our population. The overall average recall rate was 0.6% which meant that 24 normal newborns were recalled for testing for one confirmed case. The recall rate was relatively higher for galactosemia and G6PD deficiency which was at 0.25% each compared to the other conditions where it was below 0.05%. CONCLUSION: The results of the study emphasize the need for universal newborn screening especially in all government hospitals with large birth cohorts.

Classic galactosaemia in the Greek Cypriot population: An epidemiological and molecular study.

Classic galactosaemia is an inherited metabolic disorder of galactose metabolism caused by deficiency of the enzyme galactose-1-phosphate uridyltransferase (GALT) resulting from mutations in the GALT gene. The objectives of the present study were the determination of the carrier frequency of classic galactosaemia in the Greek Cypriot population and the molecular characterization of the disease alleles. We performed an epidemiological study involving 528 Greek Cypriots originating from all parts of Cyprus. Carriers were identified by measuring GALT activity in red blood cells and were subsequently subjected to mutation analysis. A total of five mutations were identified in patients and carriers of classic galactosaemia: a large deletion of 8.5 kb previously reported by us (55% of alleles), the known mutations p.Lys285Asn (30%), p.Pro185Ser (5%), and c.820+13A>G (5%), and a novel mutation c.378-12G>A (5%). Interestingly, the most common mutation in European populations, p.Gln188Arg, was not identified in this Cypriot cohort. The carrier frequency for classic galactosaemia among Greek Cypriots was estimated to be 1:88, predicting a homozygote incidence of 1:31,000 births. The Duarte 1 and Duarte 2 variants were found to be present at a frequency of 5.5% and 2.5%, respectively.

The prevalence of GALM mutations that cause galactosemia: A database of functionally evaluated variants.

Galactosemia is a metabolic disorder that affects the appropriate metabolism of ß-D-galactose. Deficiencies in three of the enzymes of the Leloir pathway, namely, GALT, GALK1, or GALE, are characterized as type I, II, and III galactosemia, respectively. Recently, we reported a novel type of galactosemia (type IV galactosemia) due to biallelic GALM mutations. Genetic diagnosis is indispensable for diagnosing GALM deficiency because no biochemical diagnosis method has been established. Given that apparently pathogenic variants in GALM are found in public variant databases, we presumed the presence of pathogenic variants that have not been reported. In this study, we explore 67 GALM variants that are prevalent in the ExAC database, including 57 missense variants, 7 stop-gain variants, 2 frameshift variants, and 1 splice-site variant. We performed an in vitro expression assay and an enzyme activity assay. Among the 66 variants except for 1 splice-site variant, 29 produced no or faint protein expression and were judged as pathogenic variants. Furthermore, the remaining 37 variants were evaluated by enzyme activity assay. Two showed mildly reduced enzyme activity and were classified as benign. Based on our study, the estimated incidence of GALM deficiency is 1:228,411 in all populations, 1:10,388 in the African population, and 1:80,747 in the Japanese population. Our GALM mutation database is useful for the genetic diagnosis of GALM deficiency.

Recommendations for newborn screening for galactokinase deficiency: A systematic review and evaluation of Dutch newborn screening data.

INTRODUCTION: Galactokinase (GALK) deficiency causes cataract leading to severe developmental consequences unless treated early. Because of the easy prevention and rapid reversibility of cataract with treatment, the Dutch Health Council advised to include GALK deficiency in the Dutch newborn screening program. The aim of this study is to establish the optimal screening method and cut-off value (COV) for GALK deficiency screening by performing a systematic review of the literature of screening strategies and total galactose (TGAL) values and by evaluating TGAL values in the first week of life in a cohort of screened newborns in the Netherlands. METHODS: Systematic literature search strategies in OVID MEDLINE and OVID EMBASE were developed and study selection, data collection and analyses were performed by two independent investigators. A range of TGAL values measured by the Quantase Neonatal Total Galactose screening assay in a cohort of Dutch newborns in 2007 was evaluated. RESULTS: Eight publications were included in the systematic review. All four studies describing screening strategies used TGAL as the primary screening marker combined with galactose-1-phosphate uridyltransferase (GALT) measurement that is used for classical galactosemia screening. TGAL COVs of 2200 µmol/L, 1665 µmol/L and 1110 µmol/L blood resulted in positive predictive values (PPV) of 100%, 82% and 10% respectively. TGAL values measured in the newborn period were reported for 39 GALK deficiency patients with individual values ranging from 3963 to 8159 µmol/L blood and 2 group values with mean 8892 µmol/L blood (SD ±â€¯5243) and 4856 µmol/L blood (SD ±â€¯461). Dutch newborn screening data of 72,786 newborns from 2007 provided a median TGAL value of 110 µmol/L blood with a range of 30-2431 µmol/L blood. CONCLUSION: Based on TGAL values measured in GALK deficiency patients reported in the literature and TGAL measurements in the Dutch cohort by newborn screening we suggest to perform the GALK screening with TGAL as a primary marker with a COV of 2500 µmol/L blood, combined with GALT enzyme activity measurement as used in the classical galactosemia screening, to ensure detection of GALK deficiency patients and minimize false positive referrals.

Association of presenile cataract with galactose-1-phosphate uridyl transferase gene mutations.

BACKGROUND: Presenile cataract is commonly idiopathic in origin. However, patients with presenile cataract could have an underlying genetic abnormality of galactose metabolism. We studied the association, if any, between idiopathic presenile cataract and galactose-1 -phosphate uridyl transferase (GALT) gene mutation. METHODS: We selected 50 patients with idiopathic presenile cataract, <45 years of age, and 50 age- and sex-matched controls for the study. Mutations in the GALT gene were determined by polymerase chain reaction restriction fragment length polymorphism. The classical galactosaemia was characterized by Q188R and K285N mutations, whereas Duarte galactosaemia by N314D mutations (Duarte-2: N314D with IVS5-24G >A and Duarte-1: N314D without IVS5- 24G>A). RESULTS: The most common mutation observed was the N314D (Duarte) mutation. The frequencies of classical and N31 4D alleles in patients with presenile cataract (16%) and controls (26%) were not statistically different (p=0.32, OR 0.54, 95% CI 0.20-1.45). Similarly, there was no statistically significant difference in the frequency distribution of Duarte-1 (p=0.77, OR 0.77, 95% CI 0.23-0.24) and Duarte-2 (p=0.44, OR 0.38, 95% CI 0.07-2.03) galactosaemia mutations in patients and controls. CONCLUSION: Duarte galactosaemia, a milder form of the disease, is more common than classical galactosaemia in the Indian population. Duarte galactosaemia is unlikely to be a causative factor in presenile cataract.

Galactosemia in the Turkish population with a high frequency of Q188R mutation and distribution of Duarte-1 and Duarte-2 variations.

Classical galactosemia is an inherited recessive disorder of galactose metabolism caused by deficiency of the enzyme galactose-1-phosphate uridyl transferase (GALT), which is caused by mutations in the GALT gene. In this study, 56 Turkish patients diagnosed with galactosemia were screened for GALT gene mutations using Affymetrix resequencing microarrays. Eleven types of mutations were detected in these patients, including two novel mutations (R258G and G310fsX49) and nine recurrent mutations. We detected six patients who were homozygous for the E340* mutation and for N314D, L218L silent substitutions (Duarte-1 variant) in this study. The haplotype E340*, N314D and L218L has been reported only in Turkish patients, which suggests that the E340* mutation is specific for our population and might be spread by a Turk ancestor. In patients, the Duarte-1 allele was found with a frequency of 10.71%, whereas the Duarte-2 allele was not detected. Duarte-1 and Duarte-2 alleles were found to be present at a frequency of 2.3% and 1.4%, respectively, in the screening of 105 healthy individuals. Considering all detected mutations, it is a very important finding that exons 6 and 10 of the GALT gene account for 79% of all mutant alleles in the Turkish population. The most common mutation is Q188R, with a frequency of 55.35%.

Cryptic residual GALT activity is a potential modifier of scholastic outcome in school age children with classic galactosemia.

Classic galactosemia is a potentially lethal disorder that results from profound deficiency of galactose-1-phosphate uridylyltransferase (GALT), the second enzyme in the Leloir pathway of galactose metabolism. Although early diagnosis and rigorous dietary restriction of galactose prevent or resolve the potentially lethal acute symptoms, patients are at markedly increased risk of long-term complications including significant cognitive, speech, and behavioral difficulties, among other problems. The mechanisms that underlie these long-term complications remain unclear, as do the factors that modify their severity. Here we explored the scholastic and behavioral outcomes experienced by a cohort of 54 school age children with classic galactosemia. Data collected included survey responses from parents and teachers, school records including standardized test scores, and GALT genotype data used to estimate predicted residual GALT activity based on a yeast expression system. As expected, many but not all of the children in our study demonstrated speech, scholastic, and behavioral difficulties. Perhaps most striking, we found that predicted cryptic residual GALT activity, often below the threshold of detection of clinical assays, appeared to modify scholastic outcome. These data raise the intriguing possibility that cryptic GALT activity might also influence the severity of other long-term complications in classic galactosemia.

Classical Galactosaemia in Ireland: incidence, complications and outcomes of treatment.

Newborn screening for the inborn error of metabolism, classical galactosaemia prevents life-threatening complications in the neonatal period. It does not however influence the development of long-term complications and the complex pathophysiology of this rare disease remains poorly understood. The objective of this study was to report the development of a healthcare database (using Distiller Version 2.1) to review the epidemiology of classical galactosaemia in Ireland since initiation of newborn screening in 1972 and the long-term clinical outcomes of all patients attending the National Centre for Inherited Metabolic Disorders (NCIMD). Since 1982, the average live birth incidence rate of classical galactosaemia in the total Irish population was approximately 1:16,476 births. This reflects a high incidence in the Irish 'Traveller' population, with an estimated birth incidence of 1:33,917 in the non-Traveller Irish population. Despite early initiation of treatment (dietary galactose restriction), the long-term outcomes of classical galactosaemia in the Irish patient population are poor; 30.6 % of patients ≥ 6 yrs have IQs <70, 49.6 % of patients ≥ 2.5 yrs have speech or language impairments and 91.2 % of females ≥ 13 yrs suffer from hypergonadotrophic hypogonadism (HH) possibly leading to decreased fertility. These findings are consistent with the international experience. This emphasizes the requirement for continued clinical research in this complex disorder.

Low prevalence of classical galactosemia in Korean population.

This study described the clinical and molecular genetic features of classical galactosemia in Korean population to contribute to the insight in the spectrum of galactosemia in the world, as little is known about the spectrum and incidence of galactosemia in Asia. During the 11-year study period, only three Korean children were identified as having classical galactosemia on the basis of the enzymatic and molecular genetic analysis. Asians have been reported to have mutations distinct from those of Caucasians and African Americans, indicating that galactose-1-phosphate uridyltransferase mutations are ethnically diverse. Our three patients had a total of three mutations (c.252+1G > A, p.Q169H and p.E363K), two of which were novel (p.E363K and c.252+1G > A) mutations. Interestingly, c.252+1G > A, which leads to skipping of exon 2, was observed in all three patients (three of six alleles), indicating that this mutation may be common in Koreans with classical galactosemia. Screening for classical galactosemia in 158,126 Korean newborns identified no patient with classical galactosemia. In conclusion, our findings provide further evidence for the ethnic diversity of classical galactosemia, which may be as rare in Koreans as in other Asian populations.

Diet and visually significant cataracts in galactosaemia: is regular follow up necessary?

INTRODUCTION: Classic galactosaemia is caused by a recessively inherited deficiency of the enzyme galactose 1 phosphate uridyl transferase (GALT). Patients with classical galactosaemia are at increased risk of developing cataracts. We sought to retrospectively review the incidence and severity of cataracts in the cohort of galactosaemia patients attending our national treatment centre and to assess a possible effect of dietary compliance on cataract formation and the benefits of regular ophthalmic follow-up. METHODS: We retrospectively reviewed the clinical notes of all patients currently attending our centre with classic galactosaemia and identified all those in whom cataracts had been diagnosed by an ophthalmologist. Compliance to diet was also reviewed and compared with a matched control group. RESULTS: Of 100 active patient charts, 14 had cataracts diagnosed at some stage. Six of these persisted whereas eight regressed. Three occurred soon after birth. Age at cataract formation varied from soon after birth to 19 years of age. There was no significant difference in the cataract group between those who were compliant and those who were noncompliant with diet (p = 0.09). There was no difference in compliance between the cataract group and the control group (p = 0.16). None of the cataracts found were affecting vision. CONCLUSION: Cataracts affecting vision were not found in our cohort. A direct relationship between dietary compliance and cataract formation was not demonstrated. On the basis of our data, regular life-long ophthalmic exam of patients with classic galactosemia seems to be unnecessary. TAKE-HOME MESSAGE: Cataracts which develop in patients with classical Galactosaemia do not usually affect vision and may be unrelated to compliance to diet.

Extensions to the Speech Disorders Classification System (SDCS).

This report describes three extensions to a classification system for paediatric speech sound disorders termed the Speech Disorders Classification System (SDCS). Part I describes a classification extension to the SDCS to differentiate motor speech disorders from speech delay and to differentiate among three sub-types of motor speech disorders. Part II describes the Madison Speech Assessment Protocol (MSAP), an ∼ 2-hour battery of 25 measures that includes 15 speech tests and tasks. Part III describes the Competence, Precision, and Stability Analytics (CPSA) framework, a current set of ∼ 90 perceptual- and acoustic-based indices of speech, prosody, and voice used to quantify and classify sub-types of Speech Sound Disorders (SSD). A companion paper provides reliability estimates for the perceptual and acoustic data reduction methods used in the SDCS. The agreement estimates in the companion paper support the reliability of SDCS methods and illustrate the complementary roles of perceptual and acoustic methods in diagnostic analyses of SSD of unknown origin. Examples of research using the extensions to the SDCS described in the present report include diagnostic findings for a sample of youth with motor speech disorders associated with galactosemia, and a test of the hypothesis of apraxia of speech in a group of children with autism spectrum disorders. All SDCS methods and reference databases running in the PEPPER (Programs to Examine Phonetic and Phonologic Evaluation Records) environment will be disseminated without cost when complete.

Long-term speech and language developmental issues among children with Duarte galactosemia.

PURPOSE: : There is limited information on long-term outcomes among children with Duarte galactosemia and controversy about treatment of this potentially benign condition. This study examined developmental disabilities and issues that required special education services within a population-based sample of children with Duarte galactosemia. METHODS: : Children born between 1988 and 2001 who were diagnosed with Duarte galactosemia and resided in the five-county metropolitan Atlanta area at birth and from 3 to 10 years of age were linked to the (1) Metropolitan Atlanta Developmental Disabilities Surveillance Program, an ongoing, population-based surveillance system for selected developmental disabilities and (2) Special Education Database of Metropolitan Atlanta. Special education records were reviewed for children who linked. Clinical genetics records were reviewed to assess laboratory levels at the time of diagnosis and metabolic control during treatment. RESULTS: : Of the 59 eligible children, none were found to have intellectual disability, cerebral palsy, hearing loss, vision impairment, or an autism spectrum disorder. However, five, 8.5% of 3 to 10 years or 15.2% of eligible 8 years, were identified as having received special education services, four of whom were confirmed with a speech or language disorder, or were receiving services for speech or language or both compared with 4.5% and 5.9% of children without Duarte galactosemia, respectively. CONCLUSIONS: : Despite galactose restriction until 1 year, select developmental issues associated with special education, specifically involving speech and language, have been found among some children with Duarte galactosemia.