Multiple phenotypes in phosphoglucomutase 1 deficiency.

BACKGROUND: Congenital disorders of glycosylation are genetic syndromes that result in impaired glycoprotein production. We evaluated patients who had a novel recessive disorder of glycosylation, with a range of clinical manifestations that included hepatopathy, bifid uvula, malignant hyperthermia, hypogonadotropic hypogonadism, growth retardation, hypoglycemia, myopathy, dilated cardiomyopathy, and cardiac arrest. METHODS: Homozygosity mapping followed by whole-exome sequencing was used to identify a mutation in the gene for phosphoglucomutase 1 (PGM1) in two siblings. Sequencing identified additional mutations in 15 other families. Phosphoglucomutase 1 enzyme activity was assayed on cell extracts. Analyses of glycosylation efficiency and quantitative studies of sugar metabolites were performed. Galactose supplementation in fibroblast cultures and dietary supplementation in the patients were studied to determine the effect on glycosylation. RESULTS: Phosphoglucomutase 1 enzyme activity was markedly diminished in all patients. Mass spectrometry of transferrin showed a loss of complete N-glycans and the presence of truncated glycans lacking galactose. Fibroblasts supplemented with galactose showed restoration of protein glycosylation and no evidence of glycogen accumulation. Dietary supplementation with galactose in six patients resulted in changes suggestive of clinical improvement. A new screening test showed good discrimination between patients and controls. CONCLUSIONS: Phosphoglucomutase 1 deficiency, previously identified as a glycogenosis, is also a congenital disorder of glycosylation. Supplementation with galactose leads to biochemical improvement in indexes of glycosylation in cells and patients, and supplementation with complex carbohydrates stabilizes blood glucose. A new screening test has been developed but has not yet been validated. (Funded by the Netherlands Organization for Scientific Research and others.).

Features and outcome of galactokinase deficiency in children diagnosed by newborn screening.

Galactokinase deficiency (GALK-D), an autosomal recessive disorder in the Leloir pathway, results in accumulation of galactose, galactitol, and galactonate and leads to early onset of juvenile bilateral cataract. Highest incidence of GALK-D is found in Romani populations. The migration wave due to the Yugoslavian civil war has changed the spectrum of inborn errors of metabolism within Europe. Hence, newborn screening (NBS) in the Berlin region, performed from 1991 until 2010 in 683,675 neonates, revealed an increased incidence of GALK-D of 1:40,000, comparable to that of galactose-1-phosphate-uridyltransferase deficiency. A total of 44% of GALK-D patients were of Romani origin. All patients of Bosnian or Serbian origin were homozygous for the Romani founder mutation p.P28T. Detection of GALK-D by NBS and early start of galactose-restricted diet resulted in regression or prevention of cataracts. Slight cataracts without visual impairment occurred in 50% of the patients, 56% of whom were noncompliant. Further clinical symptoms, e.g., hypoglycemia, mental retardation, microcephaly, and failure to thrive, were associated with noncompliance. With treatment, galactose in blood decreased from 8,892 ± 5,243 to 36.5 ± 49.3 µmol/l, galactose in urine from 31,820 ± 32,103 to 30.0 ± 36.1 µmol/mmol creatinine, galactitol in RBC from 1,584 ± 584 to 12.3 ± 9.4 µmol/l, and galactitol in urine from 11,724 ± 4,496 to 236 ± 116 µmol/mmol creatinine. This is the first presentation of outcome and clinical features in GALK-D patients diagnosed by NBS. As our data suggest, GALK-D should be considered for inclusion in NBS in populations expected to have substantial numbers of GALK-D carriers, e.g., Yugoslavian immigrants.

Molecular features of 23 patients with glycogen storage disease type III in Turkey: a novel mutation p.R1147G associated with isolated glucosidase deficiency, along with 9 AGL mutations.

Glycogen storage disease type III (GSD III) is an autosomal recessive disorder caused by deficiency in the glycogen debranching enzyme (gene symbol: AGL) with two enzyme activities: transferase and glucosidase. A missense mutation causing isolated glucosidase deficiency has never been reported. In this study, we examined 23 patients of Turkish ancestry and identified a novel missense mutation p.R1147G with isolated glucosidase deficiency, along with nine AGL mutations: six nonsense mutations (p.W373X, p.R595X, p.Q667X, p.Q1205X, p.W1327X and p.Q1376X), one deletion (c.1019delA) and two splicing mutation (c.293+2T>G and c.958+1G>A). As p.R1147G impaired glucosidase activity, but maintained transferase activity in vitro, a 12-year-old girl homozygous for p.R1147G was diagnosed with having isolated glucosidase deficiency. Of nine other mutations, p.W1327X and c.1019delA were recurrent, whereas seven mutations were novel. Six patients with p.W1327X were all from two nearby cities on the East Black Sea and shared the same AGL haplotype, indicating a founder effect in Turkish patients. Patients with the same mutations had identical haplotypes. Our results provide the first comprehensive overview of clinical and molecular features of Turkish GSD III patients and the first description of the missense mutation associated with isolated glucosidase deficiency.

Egyptian glycogen storage disease type III - identification of six novel AGL mutations, including a large 1.5 kb deletion and a missense mutation p.L620P with subtype IIId.

BACKGROUND: Glycogen storage disease type III (GSD III) is caused by mutations in AGL which encodes for a single protein with two enzyme activities: oligo-1, 4-1, 4-glucantransferase (transferase) and amylo-1, 6-glucosidase. Activity of both enzymes is lost in most patients with GSD III, but in the very rare subtype IIId, transferase activity is deficient. Since the spectrum of AGL mutations is dependent on the ethnic group, we investigated the clinical and molecular characteristics in Egyptian patients with GSD III. METHODS: Clinical features were examined in five Egyptian patients. AGL was sequenced and AGL haplotypes were determined. RESULTS: Six novel AGL mutations were identified: a large deletion (c.3481-3588+1417del1525 bp), two insertions (c.1389insG and c.2368insA), two small deletions (c.2223-2224delGT and c.4041delT), and a missense mutation (p.L620P). p.L620P was found in a patient with IIId. Each mutation was located on a different AGL haplotype. CONCLUSIONS: Our results suggest that there is allelic and phenotypic heterogeneity of GSD III in Egypt. This is the second description of a large deletion in AGL. p.L620P is the second mutation found in GSD IIId.

Unclassified polysaccharidosis of the heart and skeletal muscle in siblings.

We describe a 15-year-old boy and his 19-year-old sister with progressive dilated cardiomyopathy and mild non-progressive proximal lower limb myopathy, secondary to the accumulation of amylopectin-like fibrillar glycogen, (polyglucosan) bodies, in heart and skeletal muscle. Evidence of idiopathic amylopectinosis or polysaccharidosis was demonstrated in heart and skeletal muscle tissue by histology, electron microscopy, biochemical, and genetic analysis. In both siblings the heart muscle stored PAS-positive, proteinase-k resistant and partly diastase resistant granulo-filamentous material, simulating polyglucosan bodies. Glycogen branching enzyme activity, and phosphofructokinase enzyme activity, measured in skeletal muscle tissue and explanted heart tissue were all within the normal limits, however glycogen content was elevated. Furthermore, GBE1, PRKAG2, desmin, alphabeta-crystallin, ZASP, myotilin, and LAMP-2 gene sequencing revealed no mutation, excluding e.g. glycogen storage disease type 4 and desmin-related myofibrillar cardiomyopathies. In both patients the diagnosis of an idiopathic polysaccharidosis with progressive dilated cardiomyopathy was made, requiring heart transplantation at age 13 and 14, respectively. Both patients belong to an autosomal recessive group of biochemically and genetically unclassified severe vacuolar glycogen storage disease of the heart and skeletal muscle. Up to now unidentified glycogen synthesis or glycogen degradation pathways are supposed to contribute to this idiopathic glycogen storage disease.

Glycogen storage disease: clinical, biochemical, and molecular heterogeneity.

Glycogen storage diseases (GSDs) are characterized by abnormal inherited glycogen metabolism in the liver, muscle, and brain and divided into types 0 to X. GSD type I, glucose 6-phosphatase system, has types Ia, Ib, Ic, and Id, glucose 6-phosphatase, glucose 6-phosphate translocase, pyrophosphate translocase, and glucose translocase deficiencies, respectively. GSD type II is caused by defective lysosomal alpha-glucosidase (GAA), subdivided into 4 onset forms. GSD type III, amylo-1,6-glucosidase deficiency, is subdivided into 6 forms. GSD type IV, Andersen disease or amylopectinosis, is caused by deficiency of the glycogen-branching enzyme in numerous forms. GSD type V, McArdle disease or muscle phosphorylase deficiency, is divided into 2 forms. GSD type VI is characterized by liver phosphorylase deficiency. GSD type VII, phosphofructokinase deficiency, has 2 subtypes. GSD types VIa, VIII, IX, or X are supposedly caused by tissue-specific phosphorylase kinase deficiency. GSD type 0, glycogen synthase deficiency, is divided into 2 subtypes.

Identification of a novel mevalonate kinase gene mutation in combination with the common MVK V377I substitution and the low-penetrance TNFRSF1A R92Q mutation.

The hyperimmunoglobulinemia D and periodic fever syndrome (HIDS) is an autosomal recessively inherited autoinflammatory disease caused by mutations in the mevalonate kinase (MVK) gene on chromosome 12q24, which lead to a depressed enzymatic activity of mevalonate kinase (MK). TNF-receptor associated periodic syndrome (TRAPS), on the other hand, is the most frequent autosomal dominantly inherited periodic fever syndrome due to mutations in exons 2-4 and 6 of the TNFRSF1A gene on chromosome 12p13.2. We describe a girl with heterozygosity for the common MVK V377I mutation and for a novel T(1132) --> C transition, leading to the exchange of serine (TCC) by proline (CCC) at amino-acid position 378. Interestingly, our patient presented only with mild clinical features typical of HIDS and slightly increased immunoglobulin D levels, but a distinctly diminished MK activity. The girl was also heterozygous for the TNFRSF1A R92Q low-penetrance mutation, which may have significant proinflammatory effects. However, at the time of presentation, the patient had no TRAPS-associated symptoms.

Molecular and clinical delineation of 12 patients with glycogen storage disease type III in Western Turkey.

BACKGROUND: Glycogen storage disease type III (GSD III; MIM #232400) is an autosomal recessive inherited disorder characterized by fasting hypoglycemia, growth retardation, hepatomegaly, progressive myopathy, and cardiomyopathy. GSD III is caused by deficiency in the glycogen debranching enzyme (gene symbol: AGL). Molecular analyses of AGL have indicated heterogeneity depending on ethnic groups. In Turkey we reported 13 different AGL mutations from GSD III patients in the Eastern region; however, the full spectrum of AGL mutations in Turkish population remains unclear. Here we investigated 12 GSD III patients mostly from Western Turkey. METHODS: The full coding exons, their relevant exon-intron boundaries, and the 5'- and 3'-flanking regions of the patients' AGL were sequenced. AGL haplotypes were determined. Splicing mutations were characterized by RNA transcript analysis. RESULTS: Twelve different mutations were identified: 7 novel AGL mutations [69-base pair deletion (c.1056_1082+42del69), 21-base par deletion (c.3940_3949+11del21), two small duplications (c.364_365dupCT and c.1497_1500dupAGAG), and 3 splicing mutations (c.1736-11A>G, c.3259+1G>A and c.3588+2T>G)], along with 5 known mutations (c.1019delA, c.958+1G>A, c.4161+5G>A, p.R864X and p.R1218X). Transcripts of splicing mutations (c.1736-11A>G, c.3588+2T>G and c.4161+5G>A) were shown to cause aberrant splicing. AGL haplotype analyses suggested that c.1019delA and c.958+1G>A are founder mutations in Turkish patients, while p.R864X is a recurrent mutation. CONCLUSIONS: Our study broadens the spectrum of AGL mutations and demonstrates that mutations in Western Turkey are different from those in the Eastern region.

Clinical, Biochemical, and Genetic Characterization of Glycogen Storage Type IX in a Child with Asymptomatic Hepatomegaly.

Glycogen storage disease type IX (GSD IX) is caused by a defect in phosphorylase b kinase (PhK) that results from mutations in the PHKA2, PHKB, and PHKG2 genes. Patients usually manifest recurrent ketotic hypoglycemia with growth delay, but some may present simple hepatomegaly. Although GSD IX is one of the most common causes of GSDs, its biochemical and genetic diagnosis has been problematic due to its rarity, phenotypic overlap with other types of GSDs, and genetic heterogeneities. In our report, a 22-month-old boy with GSD IX is described. No other manifestations were evident except for hepatomegaly. His growth and development also have been proceeding normally. Diagnosed was made by histologic examination, an enzyme assay, and genetic testing with known c.3210_3212del (p.Arg1070del) mutation in PHKA2 gene.

Muscle glycogenosis with low phosphorylase kinase activity: mutations in PHKA1, PHKG1 or six other candidate genes explain only a minority of cases.

Muscle-specific deficiency of phosphorylase kinase (Phk) causes glycogen storage disease, clinically manifesting in exercise intolerance with early fatiguability, pain, cramps and occasionally myoglobinuria. In two patients and in a mouse mutant with muscle Phk deficiency, mutations were previously found in the muscle isoform of the Phk alpha subunit, encoded by the X-chromosomal PHKA1 gene (MIM # 311870). No mutations have been identified in the muscle isoform of the Phk gamma subunit (PHKG1). In the present study, we determined Q1the structure of the PHKG1 gene and characterized its relationship to several pseudogenes. In six patients with adult- or juvenile-onset muscle glycogenosis and low Phk activity, we then searched for mutations in eight candidate genes. The coding sequences of all six genes that contribute to Phk in muscle were analysed: PHKA1, PHKB, PHKG1, CALM1, CALM2 and CALM3. We also analysed the genes of the muscle isoform of glycogen phosphorylase (PYGM), of a muscle-specific regulatory subunit of the AMP-dependent protein kinase (PRKAG3), and the promoter regions of PHKA1, PHKB and PHKG1. Only in one male patient did we find a PHKA1 missense mutation (D299V) that explains the enzyme deficiency. Two patients were heterozygous for single amino-acid replacements in PHKB that are of unclear significance (Q657K and Y770C). No sequence abnormalities were found in the other three patients. If these results can be generalized, only a fraction of cases with muscle glycogenosis and a biochemical diagnosis of low Phk activity are caused by coding, splice-site or promoter mutations in PHKA1, PHKG1 or other Phk subunit genes. Most patients with this diagnosis probably are affected either by elusive mutations of Phk subunit genes or by defects in other, unidentified genes.

Congenital ocular malformations (lens subluxation, pupillary displacement, cataract, myopia) and classic galactosaemia associated with Q188R and /or G1391A mutations.

PURPOSE: Observations of multiple ocular malformations together with heterozygosity for galactosaemia in siblings and homozygosity in one child are highly unusual. In these case histories, a series of investigations in one family are reported. METHODS: Members of a family of two brothers and one sister and their children were pre- and post-surgically examined over several years. Blood examination was carried out in a laboratory specializing in investigation into genetic diseases (Dr Podskarbi, Munich). RESULTS: Two brothers and one sister suffered from cataract-induced visual deterioration at 38, 34 and 35 years of age, respectively. All three siblings reported having had bilateral poor vision since early childhood. The three siblings' parents had no congenital ocular malformations, nor was there any parental consanguinity. One child, the 10-year-old son of the 35-year-old sister, exhibited classic galactosaemia and normal ocular findings. This sister's other child was healthy. All three siblings presented congenital lens luxation, axial myopia, cataract and iridodonesis. In addition, the 34-year-old brother showed unilateral right corectopia and left coloboma adjacent to the optic disc. The 38-year-old brother revealed myopic fundus changes, but no coloboma. The three siblings experienced a distinct increase in visual acuity after cataract surgery. Both eyes of the patients were partially or distinctly amblyopic, respectively. We assume an autosomal-recessive transmission. Molecular genetic examination of the 10-year-old child with classic galactosaemia showed homozygosity for the mutation Q188R with a complete galactose-1-phosphate-uridyltransferase (GALT) deficiency. Because of his galactose-free diet, the child showed normal values for galactose-1-phosphate. The 35-year-old mother showed compound heterozygosity for Q188R and G1391A (D2/G). The 10-year-old boy's father also revealed heterozygosity for galactosaemia caused by GALT deficiency. The two children of the 38-year-old brother were heterozygous for G1391A. They did not show any clinical abnormality. None of the family members had clinical signs of Marfan's syndrome or homocysteinuria. The three siblings' parents were not consanguineous. CONCLUSIONS: Patients with worsening cataracts occurring at a pre-senile age should be examined for galactosaemia. We describe for the first time the molecular genetic findings in congenital ectopia lentis et pupillae. Early treatment in conjunction with a galactose-free diet is mandatory in patients with galactosaemia. Members of a family with heterozygosity for galactosaemia should be advised to attend a human genetic consultation.

Early cataract formation due to galactokinase deficiency: impact of newborn screening.

BACKGROUND AND AIMS: Galactokinase (GALK) deficiency is an autosomal recessive disorder causing cataract formation that can be prevented or mitigated by early diagnosis and galactose-restricted diet. The aim of this retrospective study was to explore whether GALK-deficiency meets the criteria for neonatal mass screening programs. METHODS: From 2000 until 2010, the Screening Laboratory Hannover performed newborn screening in 1,950,927 infants from Germany for galactosemia by measuring galactose-1-phosphate-uridyl-transferase and total galactose concentration (free galactose plus galactose-1-phosphate), including automatic screening for GALK deficiency. RESULTS: Eleven cases were found with elevated galactose levels accompanied by normal transferase activity. Nine of 11 cases were informative; the diagnosis was established by demonstrating deficient activity of the GALK enzyme in erythrocytes. To our knowledge, screening did not produce any false negative results. All patients were treated with a galactose-restricted diet from the neonatal period or infancy. Three of nine patients suffered from congenital cataracts or eventual development of cataracts, despite normal galactose concentrations in blood. CONCLUSIONS: Newborn screening for GALK deficiency prevents or at least mitigates cataract formation. As screening for GALK deficiency is technically simple, it seems to be reasonable to include this disorder in routine screening programs by simultaneous determination of transferase activity and quantification of galactose plus galactose-1-phosphate in dried blood spots.

A Japanese patient with cardiomyopathy caused by a novel mutation R285X in the AGL gene.

Left ventricular hypertrophy (LVH) is primarily or secondarily caused by a cardiovascular or systemic disease. The pattern of LVH is distinctive in hypertrophic or metabolic cardiomyopathy and differs from that seen in LVH caused by hypertension or aortic stenosis. A 42-year-old Japanese man had LVH similar to that with hypertrophic cardiomyopathy. The patient was diagnosed with glycogen storage disease type IIIa (GSD-IIIa). Echocardiography showed that he had severe LVH, and concomitant hepatomegaly and hypoglycemia, which led to measurement of glycogen debranching enzyme (GDE) activity; it was undetectable. Sequence analysis of the AGL gene encoding GDE showed a novel nonsense mutation: a C-to-T transition at codon 285 in exon 8, resulting in substitution of the arginine codon by the stop codon (R285X). The patient was homozygous for the mutation. Cardiomyopathy in this patient was caused by a nonsense mutation in the AGL gene. Five other Japanese GSD-IIIa patients over 30 years of age have all presented with cardiomyopathy, as well as hepatomegaly and hypoglycemia. Patients with LVH associated with hepatomegaly and hypoglycemia should undergo biochemical and genetic analyses for GSD-IIIa.

Molecular analysis of the AGL gene: heterogeneity of mutations in patients with glycogen storage disease type III from Germany, Canada, Afghanistan, Iran, and Turkey.

Glycogen storage disease type III (GSD III) is an autosomal recessive disorder characterized by excessive accumulation of abnormal glycogen in the liver and/or muscles and caused by deficiency in the glycogen debranching enzyme (AGL). Previous studies have revealed that the spectrum of AGL mutations in GSD III patients depends on ethnic grouping. We investigated nine GSD III patients from Germany, Canada, Afghanistan, Iran, and Turkey and identified six novel AGL mutations: one nonsense (W255X), three deletions (1019delA, 3202-3203delTA, and 1859-1869del11-bp), and two splicing mutations (IVS7 + 5G > A and IVS21 + 5insA), together with three previously reported ones (R864X, W1327X, and IVS21 + 1G > A). All mutations are predicted to lead to premature termination, which abolishes enzyme activity. Our molecular study on GSD III patients of different ethnic ancestry showed allelic heterogeneity of AGL mutations. This is the first AGL mutation report for German, Canadian, Afghan, Iranian and Turkish populations.

Molecular characterization of Egyptian patients with glycogen storage disease type IIIa.

Glycogen storage disease type IIIa (GSD IIIa) is an autosomal recessive disorder characterized by excessive accumulation of abnormal glycogen in the liver and muscles and caused by a deficiency in the glycogen debranching enzyme. The spectrum of AGL mutations in GSD IIIa patients depends on ethnic group-prevalent mutations have been reported in the North African Jewish population and in an isolate such as the Faroe islands, because of the founder effect, whereas heterogeneous mutations are responsible for the pathogenesis in Japanese patients. To shed light on molecular characteristics in Egypt, where high rate of consanguinity and large family size increase the frequency of recessive genetic diseases, we have examined three unrelated patients from the same area in Egypt. We identified three different individual AGL mutations; of these, two are novel deletions [4-bp deletion (750-753delAGAC) and 1-bp deletion (2673delT)] and one the nonsense mutation (W1327X) previously reported. All are predicted to lead to premature termination, which completely abolishes enzyme activity. Three consanguineous patients are homozygotes for their individual mutations. Haplotype analysis of mutant AGL alleles showed that each mutation was located on a different haplotype. Our results indicate the allelic heterogeneity of the AGL mutation in Egypt. This is the first report of AGL mutations in the Egyptian population.

Delayed or late-onset type II glycogenosis with globular inclusions.

Three unrelated patients, one girl, one boy, and an adult female, aged 14, 11 and 41 years, respectively, at the time of biopsy, revealed lysosomal glycogen storage, autophagic vacuoles and peculiar globular inclusions of distinct ultrastructure, which were reducing but did not appear like true "reducing bodies" as described in the congenital myopathy "reducing body myopathy". All three patients had residual activity of acid alpha-glucosidase in their muscle biopsy samples. Leukocytes in the girl showed normal acid alpha-glucosidase activity, but in the boy activity was reduced. Molecular genetic analysis of the GAA gene revealed disease-causing mutations in each patient: H568L/R672W, IVS1-13T>G/G615F, and IVS1-13T>G/IVS1-13T>G. Although only one patient with such globular inclusions has been reported up to now, the three patients described here indicate that in the late-onset type of GSD II such inclusions may not be rare.

[Ocular Manifestation of Mucopolysaccharidosis I-S (Scheie's Syndrome)]. / Okuläre Manifestation bei Mukopolysaccharidose I-S (Scheie-Syndrom).

BACKGROUND: Bilateral stromal corneal opacifications are a differential diagnostical challenge to identify associated systemic diseases. CASE-REPORT: A 47-year old civil engineer (height 167 cm) with bilateral stromal corneal clouding presented with visual loss for the last 27 years: VA 20/100 OD and 20/50 OS (following penetrating keratoplasty OS). The cornea showed milky-whitish, cloudy, diffuse stromal deposits without a separate lipoid arc. The posterior segment showed tapetoretinal degeneration. Scotopic ERG was decreased. A suspicious stiffness of interphalangeal joints on both hands was observed. There was an aortic and mitral insufficiency grade I. Serum levels of LDL, HDL and triglycerides were normal. The biomicroscopical diagnosis of Scheie's syndrome (mucopolysaccharidosis I-S) was confirmed by a deficiency of alpha-L-iduronidase in leukocytes (0.02 nmol/min/mg protein, normal range: 0.3 - 1.5). CONCLUSION: The differential diagnosis of bilateral corneal stromal opacification includes in addition to the mucopolysaccharidoses HDL-deficiency diseases (LCAT deficiency, Tangier disease, Fish eye disease), Schnyder's crystalline stromal dystrophy, cystinosis, gout and mucolipidoses. MPS I-S may easily be detected by alpha-L-iduronidase deficiency in leukocytes and increased mucopolysaccharides in the urine. Furthermore, patients with MPS I-S need general medical care because of cardiovascular abnormalities, joint stiffness and myopathies.

An unexpectedly high frequency of hypergalactosemia in an immigrant Bosnian population revealed by newborn screening.

In galactokinase (GALK) deficiency, galactose cannot be phosphorylated into galactose-1-phosphate, which leads to cataract formation. Neonatal screening for hypergalactosemia in Berlin has been performed by thin-layer chromatography since 1978, which detects classical galactosemia and GALK deficiency. Until 1991, GALK deficiency has not been identified in a total of approximately 260,000 samples. In contrast, from 1992 to 1999, nine patients were detected in a total of approximately 240,000 screened newborns. One Turkish patient was homozygous for two novel S142I/G148C GALK mutations in close proximity to the putative ATP-binding site of the enzyme. The other eight children were born to five families belonging to the Bosnian refugee population consisting of approximately 30,000 individuals who have arrived in Berlin since 1991. In two of these families, GALK deficiency was subsequently diagnosed in siblings who had cataract surgery at 4 and 5 y of age, respectively. In all these 10 Bosnian patients, a homozygous P28T mutation located near the active center of the enzyme was identified. We propose that neonatal screening of populations with a significant proportion of Bosnians and possibly other southeastern Europeans, e.g. Romani, should be particularly directed toward GALK deficiency, an inborn error of metabolism that is readily amenable to effective treatment.