Galactosemia Research Articles

Newborn Screening for Galactosemia: A Review of 5 Years of Data and Audit of a Revised Reporting Approach

Availability of the galactose-1-phosphate uridyltransferase (GALT) assay for newborn (NB) screening has improved identification of classic galactosemia. Previously defined critical cutoffs for total galactose (Gal), typically 1.110 mmol/L (20 mg/dL), are still in use in laboratories measuring total Gal for the diagnosis of nonclassic galactosemias. Urgent notification/referral to a treatment center follows, although few of the NBs will need treatment. We reviewed all NB galactosemia-screening results and their corresponding clinical outcomes over a 5-year period (first phase, 1.32 x 10(6) NBs) and then over a 2-year period (second phase, 274 960 NBs). Each NB was screened for Gal and GALT. When Gal was increased and/or GALT was deficient, testing for percentage galactose-1-phosphate and/or DNA testing for common GALT mutations were performed. Of 209 reported positive results, 89% did not indicate GALT deficiency. These non-GALT-deficient results represented mostly clinically benign cases with a Gal threshold of > or = 1.110 mmol/L (> or = 20 mg/dL). The positive predictive value of a GALT cutoff of < or = 40 micromol/L was 83%. After a protocol change that redefined a critical result as a GALT value < or = 40 micromol/L and/or a Gal value > or = 1.665 mmol/L (> or = 30 mg/dL), results were monitored for an additional 2 years. The new protocol dramatically reduced the number of urgent calls/referrals and reduced the total number of referrals by nearly half. Use of a GALT cutoff of < or = 40 micromol/L/L and a Gal cutoff of > or = 1.665 mmol/L (> or = 30 mg/dL) for urgent notification/referral dramatically reduces false positives and unnecessary follow-up, thereby reducing the stress on healthcare resources.

Vertical sandwich‐type continuous/evaporative TLC with fixed mobile phase volume for separating sugars of clinical relevance in paper‐borne urine and blood samples in newborn screening

We describe the history and current implementation of an inexpensive thin layer chromatography (TLC) method, vertical sandwich-type continuous/evaporative TLC with fixed mobile phase volume, that is convenient for detecting and identifying reducing sugars of clinical relevance in the paper-borne blood and urine samples collected in neonatal screening programmes. This method facilitates screening by providing a considerable degree of standardization of chromatographic results. Among some 555,000 newborns to which it has been applied, it has detected 10 cases of classical galactosaemia, 7 cases of galactokinase deficiency, 2 cases of glucosuria, and 3 cases of transitory neonatal diabetes mellitus; the only false negatives we are aware of were two cases of galacto-4-epimerase deficiency detected by tandem mass spectrometry. Screening for sugars in urine has allowed the detection of galactosaemia when the accompanying blood sample was invalid because of transfusion or parenteral feeding. The conclusion is that this inexpensive procedure is very useful for the detection of relevant metabolopathies in circumstances where others fail.

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

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. 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. 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. 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. Cataracts which develop in patients with classical Galactosaemia do not usually affect vision and may be unrelated to compliance to diet.

Classical galactosemia in Estonia: selective neonatal screening, incidence, and genotype/phenotype data of diagnosed patients

Classical galactosemia (McKusick 230400) is an autosomal recessive genetic disease caused by deficiency of galactose-1-pbospbate uridyltransferase (GALT) activity. The gene that encodes GALT is located on chromosome 9p13, and more than 230 mutations have been identified so far (Calderon et al 2007).

Molecular and clinical analysis of patients with classic and Duarte galactosemia in western Hungary

Classic galactosemia is an autosomal recessively inherited disorder caused by deficient activity of the enzyme galactose-1-phosphate uridyltransferase. The disorder can be detected by newborn screening and in Hungary the national screening program was launched in 1976 with two screening centers. The aim of this study was the molecular characterization of the genotypes and analysis of genotype-phenotype correlation among patients with classic or variant galactosemia. DNA samples from 40 patients were analyzed by polymerase chain reaction followed by direct sequencing. 16 different sequence variations were identified, including two novel missense mutations (p.S297P, p.E146D). The two most common mutations were p. Q188R and p.K285N with allele frequencies of 45% and 31.2%, respectively. Clinical data were evaluated with respect to the genotypes found. The most serious clinical phenotypes in our population were associated with mutations p. Q188R, p.K285N, p.X380R, p.S297P, p.M142K, p.R.204X, p.Q169K and p.R407P, but manifestations depend on other genetic and environmental factors.

Longitudinal Assessment of Intellectual Achievement in Patients With Classical Galactosemia

To conduct a longitudinal assessment of long-term cognitive outcome in patients with classical galactosemia. Inclusion criteria were (1) previous assessment of IQ dating back >10 years with tests being comparable with the recent German tests HAWIK-III and HAWIE-R, (2) absence of illnesses other than galactosemia, (3) absence of foreign language problems, (4) enzymatic-metabolic proof of classical galactosemia, (5) compliance with dietary therapy, and (6) written informed consent. Twenty-three patients who fulfilled these criteria were found. They underwent the first IQ test at a mean age of 11 +/- 5 years and the second 13.6 to 15.5 years later at a mean age of 26 +/- 5 years. Results were corrected for the obsolescence of test norms (Flynn effect). Mean total IQ scores on the first and second tests were 78 +/- 14 and 73 +/- 15, respectively, and not significantly different. IQ scores in the average range were observed for 7 patients on the first test and for 5 patients on the second test. For 17 patients, the intraindividual IQ scores remained essentially unchanged. Five patients showed a decrease and 1 an increase of the IQ score over time. No consistent pattern of change was found with respect to performance or verbal IQ subscores or in achievements in the individual subtest. The results confirm the presence of reduced cognitive ability in classical galactosemia and present evidence for an absence of substantial galactosemia-induced aggravation of this impairment with increasing age, at least in patients from 4 to 40 years of age. It remains to be clarified whether a reduction of cognitive function in galactosemia may be initiated by an in utero toxicity of endogenously formed galactose and which role such a process may play in the development of intellectual deficiencies that are later maintained throughout life.

Coexistence of Duarte 1 and Duarte 2 variants of galactosemia with extrahepatic biliary atresia

Galactosemia is an autosomal recessive disorder caused by deficient or absent activities of one of the three enzymes involved in the galactose metabolic pathway. The predominant form is classic type galactosemia caused by severe reduction or absence of the galactose- 1-phosphate uridyl transferase (GALT) enzyme. Coexistence of extrahepatic biliary atresia (EHBA) with Duarte 1 and 2 variants of galactosemia has not been described earlier. Here we report a case of EHBA with concordant Duarte 1 and 2 variants of galactosemia in an infant with cholestasis. Genetic analysis of the index patient for galactosemia revealed presence of Duarte 1/Duarte 2 variants of galactosemia with genotype N314D-L218L/N314D-G1105C-GI391A- G1323A-5’UTR-119delGTCA. Clinical evaluation of the patient showed the presence of EHBA. Henceforth, it may be hypothesized that EHBA may have a genetic basis with simultaneous involvement of the GALT gene.

Remarkable differences: the course of life of young adults with galactosaemia and PKU

Although the need for insight in factors influencing the quality of life of patients with an inborn error of metabolism is recognized, psychological adjustment of adults with metabolic diseases has not been properly studied. Adult patients with PKU were demonstrated not to differ from healthy controls in terms of their course of life (CoL) and health-related quality of life (HRQoL). However, adults with galactosaemia had a lower HRQoL with significant lower scores on the domains of cognitive and social function. This study investigated the CoL and the social demographical outcomes in these young adults with galactosaemia, and compared them with the general population and with PKU patients. A total of 15 (88%) adult patients with classical galactosaemia participated in this study. Classical galactosaemia patients had a delayed social and psychosexual development compared to their peers from the general population and to PKU patients. Also, they were significantly less frequently married or living together and significantly less frequently employed than the general population. Our study shows a stark contrast between patients with galactosaemia and patients with PKU, although both are diagnosed in the neonatal period and need life-long dietary restrictions. The observed difference is likely due to the long-term somatic complications frequently seen in galactosaemia and thus not due to the burden of a chronic disease necessitating life-long dietary restrictions. We conclude that it is essential that parents and clinicians encourage children with galactosaemia to participate in peer-related activities in order to stimulate social performance, which may result in a more normal CoL.

Gonadal function in male and female patients with classic galactosemia

Hypergonadotropic hypoestrogenic infertility is the most burdensome complication for females suffering from classic galactosemia. In contrast, male gonadal function seems less affected. The underlying mechanism is not understood and several pathogenic mechanisms have been proposed. Timing of the lesion, prenatal or chronic post-natal, or a combination of both are not yet clear. This review focuses on gonadal function in males and females, ovarian imaging and histology in this disease. It is based on the literature known to the authors and a Pubmed search using the keywords galactosemia, GALT deficiency, (premature) ovarian failure/insufficiency/dysfunction, testicular function, gonadotrophins, FSH, LH (published between January 1971 and April 2009). Male gonads are less affected, boys spontaneously reach puberty, although onset can be delayed. Semen quality has not been extensively studied. Several affected males are known to have fathered a child. Female gonads are invariably affected, although to a varied extent (hypergonadotropic hypoestrogenic ovarian dysfunction). Intriguingly, FSH is often already increased in infancy. Imaging usually shows hypoplastic and streak-like ovaries. Histological findings in some cases reveal the presence of morphologically normal but decreased numbers of primordial follicles, with the absence of intermediate and Graafian follicles. Gonads in males seem less affected than in females who exhibit hypergonadotropic hypoestrogenic subfertility. FSH can be elevated in infancy, and ovarian histology sometimes shows the presence of normal primordial follicles with absence of intermediate and Graafian follicles. These findings are similar to other genetic diseases primarily affecting the ovary.

The role of human demographic history in determining the distribution and frequency of transferase-deficient galactosaemia mutations

Classical or transferase-deficient galactosaemia is an inherited metabolic disorder caused by mutation in the human Galactose-1-phosphate uridyl transferase (GALT) gene. Of some 170 causative mutations reported, fewer than 10% are observed in more than one geographic region or ethnic group. To better understand the population history of the common GALT mutations, we have established a haplotyping system for the GALT locus incorporating eight single nucleotide polymorphisms and three short tandem repeat markers. We analysed haplotypes associated with the three most frequent GALT gene mutations, Q188R, K285N and Duarte-2 (D2), and estimated their age. Haplotype diversity, in conjunction with measures of genetic diversity and of linkage disequilibrium, indicated that Q188R and K285N are European mutations. The Q188R mutation arose in central Europe within the last 20 000 years, with its observed east-west cline of increasing relative allele frequency possibly being due to population expansion during the re-colonization of Europe by Homo sapiens in the Mesolithic age. K285N was found to be a younger mutation that originated in Eastern Europe and is probably more geographically restricted as it arose after all major European population expansions. The D2 variant was found to be an ancient mutation that originated before the expansion of Homo sapiens out of Africa.

Galactose-1-Phosphate Uridyl Transferase Deficiency Is Not Associated with Müllerian Aplasia in Dutch Patients

Study Objective To study whether a deficiency in galactose-1-phosphate uridyl transferase (GALT) activity of mothers was an explanation for the occurrence of Müllerian aplasia of their daughters. Design A case control study. Setting The patients were selected from the outpatient clinic of the University Medical Center Nijmegen, and compared with the general population in The Netherlands. Participants Patients (n = 9) diagnosed with the syndrome of Müllerian aplasia and their mothers were included. Interventions A questionnaire for medical and family history was taken, and a venous blood sample and urine were collected. Main Outcome Measures GALT activity (in blood), galactose and galactilol (in urine) were measured. Measured values were analyzed by Student's paired t-test. Results All patients and their mothers had normal GALT activities ≥ 20 μmol/h/g Hb. The mean value did not differ from the mean of the normal Dutch population, which was 31.6 (SD = 5.0) μmol/h/g Hb. Conclusion GALT deficiency is not an explanation for Müllerian aplasia, at least in the Dutch population.

Frequencies of the Los Angeles and Duarte galactose-1-phosphate uridyltransferase variant alleles in the Hungarian population

Classical galactosaemia is an autosomal recessively inherited disorder caused by deficient activity of the enzyme galactose-1-phosphate uridyltransferase (GALT), which can be detected by newborn screening. The p.N314D mutation defines two variant forms of the GALT enzyme, the Los Angeles and Duarte, depending on the presence of additional base changes. The aim of our study was to analyze a healthy Hungarian population for the frequencies of the Los Angeles and Duarte galactose-1-phosphate uridyltransferase variant alleles. DNA samples from 100 subjects were analyzed by polymerase chain reaction, followed by digestion with restriction endonucleases. The frequencies of the p.N314D, the Los Angeles and the Duarte variants were 11.5%, 2.5% and 9%, respectively. The allele frequencies of the Los Angeles and Duarte variant alleles in the Hungarian population correlate well with the allele frequencies in other healthy Caucasian populations.

Negative screening tests in classical galactosaemia caused by S135L homozygosity

Classical galactosaemia is relatively common in Ireland due to a high carrier rate of the Q188R GALT mutation. It is screened for using a bacterial inhibition assay (BIA) for free galactose. A Beutler assay on day one of life is performed only in high risk cases (infants of the Traveller community and relatives of known cases). A 16-month-old Irish-born boy of Nigerian origin was referred for investigation of developmental delay, and failure to thrive. He had oral aversion to solids and his diet consisted of cow's milk and milk-based cereal mixes. He was found to have microcephaly, weight <2nd percentile, hepatomegaly and bilateral cataracts. Coagulation screen was normal and transaminases were slightly elevated. His original newborn screen was reviewed and confirmed to have been negative; urinary reducing substances on three separate occasions were negative. Beutler assay demonstrated "absent" red cell galactose-1-phosphate uridyltransferase (GALT) activity. GALT enzyme activity was <0.5 gsubs/h per gHb confirming classical galactosaemia. Gal-1-P was elevated at 1.88 micromol/gHb. Mutation analysis of the GALT gene revealed S135L homozygosity. S135L/S135L galactosaemia is associated with absent red cell GALT activity but with approximately 10% activity in other tissues such as the liver and intestines, probably explaining the negative screening tests and the somewhat milder phenotype associated with this genotype. The patient was commenced on galactose-restricted diet; on follow-up at 2 years of age, growth had normalized but there was global developmental delay. In conclusion, galactosaemia must be considered in children who present with poor growth, hepatomegaly, developmental delay and cataracts and GALT enzyme analysis should be a first line test in such cases. Non-enzymatic screening methods such as urinary reducing substances and BIA for free galactose are not reliable in S135L homozygous galactosaemia.

An update on the molecular analysis of classical galactosaemia patients diagnosed in Spain and Portugal: 7 new mutations in 17 new families

Classical galactosaemia is an inherited metabolic disorder due to mutations in the galactose-1-phosphate uridyltransferase gene (GALT). We previously reported molecular analysis of 83 Spanish and Portuguese unrelated galactosaemic patients. Here we present the results of another seventeen unreported affected individuals. DNA from patients was PCR-amplified and sequenced following standard protocols. Twelve patients diagnosed in Spain were studied. We detected five alleles carrying p.Q188R, accounting for 21%. Other six alleles (25%) were identified with the mutation p.K285N. We also identified six novel mutations: p.Q9X, c.328+2T>C, p.I170N, p.C180F, p.V233L and p.P257L. Taking into account all the Spanish galactosaemic diagnosed patients, mutation p.Q188R is still the most frequent mutation identified (44.4%). In five new Portuguese patients, five alleles p.Q188R were detected, representing 50%. One novel mutation (p.F171C) was identified. Our results confirm our previous observations that p.Q188R is the most frequent mutation in Iberian Peninsula galactosaemic patients (49%), and that Portuguese and Spanish genotypes differ.

Functional studies of rat galactokinase

Galactokinase is an ATP-dependent enzyme that catalyzes the phosphorylation of galactose to form galactose-1-phosphate. The defect in human galactokinase can result in the disease of galactosemia. On the other hand, the control of galactose-1-phosphate production by inhibiting galactokinase is a potential therapy for another disease referred to as classic galactosemia. Many pharmaceutically important compounds derive from carbohydrate-containing natural products, and glycorandomization is one of the most efficient approaches for complex secondary metabolites. Therefore, it is important to further understand the interaction between galactokinase and its substrate or substrate analogs. In the present study, we cloned and purified both N- and C-terminal His-tagged rat galactokinase. We then constructed and purified a variety of variant enzymes, which were studied using kinetics with galactose and its analogs as substrates. We found that the binding of the ATP may induce conformational change to the enzyme so that the enzyme can bind galactose specifically. Asp186 was found to be a possible catalytic residue. The mutants were incubated with fluorescent trinitrophenyl-ATP for the characterization of their ATP binding sites. Various other substrate analogs, aminoglycosides and flavanoids were also tested and found to be competitive inhibitors of rat galactokinase.

Pregnancy in classic galactosemia despite undetectable anti-Müllerian hormone

To report a pregnancy in a patient with classic galactosemia despite signs of no ovarian reserve to draw attention to the limited predictive value of ovarian reserve tests in these patients. Case report. Secondary and tertiary care center. A patient with classic galactosemia with premature ovarian failure and two previous pregnancies. Exogenous FSH ovarian reserve test and anti-Müllerian hormone (AMH) measurement. 17beta-Estradiol response, AMH level. Pregnancy despite undetectable AMH (<0.1 microg/L) and no E(2) response (exogenous FSH ovarian reserve test). Fluctuating premature ovarian failure makes fertility counseling of patients with classic galactosemia difficult. Commonly used ovarian function and reserve tests seem to have no significance.

Outcomes of Siblings with Classical Galactosemia

To determine the long-term outcome of dietary intervention in siblings from 14 Irish families with classical galactosemia (McKusick 230400), an autosomal recessive disorder of carbohydrate metabolism and galactose-1-phosphate uridyltransferase (GALT) deficiency. Outcomes in siblings on dietary galactose restriction were studied to evaluate whether birth order (ie, time of commencement of diet) and compliance with lactose-restricted diet (galactose intake > or < 20 mg /day), assessed by dietary recall and biochemical monitoring of galactose-1-phosphate [Gal-1-P] and galactitol values, affected outcomes. The outcome variables assessed were IQ, speech, and language assessment scores, neurologic examination results, and magnetic resonance imaging (MRI) of the brain. There was a high incidence of complications in the overall group, particularly speech and language delay (77%) and low IQ (71%). There was no significant difference in outcome between earlier-treated and later-treated siblings or any correlation with mean Gal-1-P or galactitol values. In most cases, cerebral white matter disease was evident on MRI scanning, with evidence of progressive cerebellar degeneration seen in 2 highly compliant families. The subjects with a higher galactose intake did not exhibit an increased incidence of complications; conversely, those who were very compliant with dietary restrictions did not have more favorable outcomes.

Plasma lysosomal enzyme activities in congenital disorders of glycosylation, galactosemia and fructosemia

Background Variable increases in the plasma activity of different lysosomal enzymes have been reported in patients with congenital disorders of glycosylation (CDG). In particular, elevated plasma aspartylglucosaminidase activity (AGA) has been found in the majority of CDG type I patients. We report on the plasma activity of AGA and other lysosomal enzymes in patients with different types of primary and secondary CDG defects. Methods AGA, α-mannosidase, β-mannosidase and β-hexosaminidase activities were assayed in the plasma of patients with CDGI (4CDGIa, 4CDGIx) and CDGIIx (5, all with a combined N- and O-glycosylation defect), classical galactosemia (GALT) ( n = 3) and hereditary fructose intolerance (HFI) ( n = 2). Results Increased AGA and β-hexosaminidase activities were found in all and 7/8 of the GDGI patients respectively. All enzymic activities were normal in the CDGIIx patients. Elevated AGA and β-hexosaminidase activity was also seen in GALT and HFI patients before treatment, when transferrin isoelectric focusing (TfIEF) patterns were also abnormal. Conclusions Increased AGA plasma activity, although a consistent finding in CDGI patients, is not specific to this group of disorders since it is also observed in untreated cases of GALT and HFI. Furthermore, plasma AGA activity cannot serve as a marker for CDGII disorders. In conjunction with TfIEF it could be used in the follow up of GALT and HFI patients.

Galactosemia Screening by Simultaneous Blood Spot Quantification of Galactose and Galactose 1-Phosphate

Galactosemia, caused by enzyme deficiencies of galactose metabolism, leads to the accumulation of galactose (Gal)1 and galactose 1-phosphate (Gal 1-P) in blood. The disease is classified into 3 types. The concentrations of Gal and Gal 1-P in galactose 1-phosphate uridyltransferase (GALT) or galactokinase (GALK) deficiency are quite different (1). Therefore, simultaneous monitoring of Gal and Gal 1-P in blood is useful to distinguish infants with GALT deficiency (type I) from those with GALK deficiency (type II). Of the various methods for determining Gal or Gal 1-P in blood spots, none are suitable for simultaneous and direct measurement because of the requirements of special reagents or multistep and time-consuming procedures (2)(3). We developed a novel method based on high-performance anion-exchange chromatography (HPAEC)–pulsed amperometric detection (PAD) that simultaneously measures Gal and Gal 1-P concentrations in patient blood spots. We prepared blood spot standards using healthy male adult blood and stock solutions of Gal and Gal 1-P. We collected blood spot specimens (70 controls and 12 patients) from Korean newborns within 3 days after birth. All of the samples were identified by quantifying Gal concentrations using the enzymatic colorimetric method (ECM) (3). Two 3.2 mm–diameter filter paper …

Low allelic heterogeneity in a sample of Mexican patients with classical galactosaemia

Classical galactosaemia is an autosomal recessive disease of galactose metabolism caused by a deficiency of the enzyme galactose-1-phosphate uridyltransferase (GALT). Galactosaemia is not included in the neonatal screening programme in Mexico and it is necessary to implement methodologies for prompt diagnosis of these patients to establish treatment. To date, more than 190 mutations in the GALT gene have been reported, most in caucasian populations, but there have been no reports of mutations in Latin-American populations. We report here the mutational spectrum in 19 Mexican galactosaemic patients. The most frequent mutations were p.Q188R, p.N314D and IVS2-2A>G, which together represented 71% of detected mutations. The mutation IVS2-2A>G, which has been detected only in Hispanics, was thought to generate a null allele; we identified one patient with a homozygous IVS2-2A>G mutation who showed a mild deficiency of enzyme value in erythrocytes. One patient homozygous for Duarte 2 (p.N314D, IVS5+62G>A) is probably due to a partial uniparental disomy of chromosome 9. In addition, a novel mutation c.336T>C (p.S112R) was detected in one patient with severe enzymatic deficiency. Despite the small number of patients studied, our results suggest that classical galactosaemia shows low allelic heterogeneity in Mexican patients, in contrast what is observed in other Mendelian disorders such as cystinosis or autosomal dominant hypercholesterolaemia. This low allelic heterogeneity might be explained by a "population of origin" effect in the central region of Mexico, as has been described for phenylketonuria.