Clinical and molecular diagnosis of non-phosphomannomutase 2 N-linked congenital disorders of glycosylation in Spain.

The congenital disorders of glycosylation (CDG) are defects in glycoprotein and glycolipid glycan synthesis and attachment. They affect multiple organ/systems, but non-specific symptoms render the diagnosis of the different CDG very challenging. Phosphomannomutase 2 (PMM2)-CDG is the most common CDG, but advances in genetic analysis have shown others to occur more commonly than previously thought. The present work reports the clinical and mutational spectrum of 25 non-PMM2 CDG patients. The most common clinical symptoms were hypotonia (80%), motor or psychomotor disability (80%) and craniofacial dysmorphism (76%). Based on their serum transferrin isoform profile, 18 were classified as CDG-I and 7 as CDG-II. Pathogenic variations were found in 16 genes (ALG1, ALG6, ATP6V0A2, B4GALT1, CCDC115, COG7, DOLK, DPAGT1, DPM1, GFPT1, MPI, PGM1, RFT1, SLC35A2, SRD5A3, and SSR4). Overall, 27 variants were identified, 12 of which are novel. The results highlight the importance of combining genetic and biochemical analyses for the early diagnosis of this heterogeneous group of disorders.

Two novel variants of the ABCG5 gene cause xanthelasmas and macrothrombocytopenia: a brief review of hematologic abnormalities of sitosterolemia.

Essentials Diagnosis of sitosterolemia, a rare recessive or syndromic disorder, is usually delayed. Peripheral blood smear is extremely useful for establishing the suspicion of sitosterolemia. High-throughput sequencing technology enables the molecular diagnosis of inherited thrombocytopenias. Accurate characterization of sitosterolemia helps us determine appropriate management. SUMMARY: Background Sitosterolemia (STSL) is a recessive inherited disorder caused by pathogenic variants in the ABCG5 and ABCG8 genes. Increased levels of plasma plant sterols (PSs) usually result in xanthomas and premature coronary atherosclerosis, although hematologic abnormalities may occasionally be present. This clinical picture is unfamiliar to many physicians, and patients may be at high risk of misdiagnosis. Objectives To report two novel ABCG5 variants causing STSL in a Spanish patient, and review the clinical and mutational landscape of STSL. Patient/Methods A 46-year-old female was referred to us with lifelong macrothrombocytopenia. She showed familial hypercholesterolemia-related xanthomas. Molecular analysis was performed with high-throughput sequencing. Plasma PS levels were evaluated with gas-liquid chromatography. The STSL landscape was reviewed with respect to specific online databases and all reports published since 1974. Results A blood smear revealed giant platelets and stomatocytes. Novel compound heterozygous variants were detected in exons 7 (c.914C>G) and 13 (c.1890delT) of ABCG5. The patient showed an increased plasma level of sitosterol. These findings support the diagnosis of STSL. In our review, we identified only 25 unrelated STLS patients who presented with hematologic abnormalities including macrothrombocytopenia. It remains unknown why only some patients develop hematologic abnormalities. Conclusions This is the first Spanish STSL patient to be reported and molecularly characterized. The early diagnosis of STLS is strongly supported by the presence of stomatocytes in blood smears. The definitive diagnosis of STSL by measurement of serum PS levels and molecular analyses prompted the use of ezetimibe therapy.

Clinical, molecular and biochemical characterization of nine Spanish families with Conradi-Hünermann-Happle syndrome: new insights into X-linked dominant chondrodysplasia punctata with a comprehensive review of the literature.

BACKGROUND: Conradi-Hünermann-Happle syndrome (CDPX2, OMIM 302960) is an inherited X-linked dominant variant of chondrodysplasia punctata which primarily affects the skin, bones and eyes. CDPX2 results from mutations in EBP (emopamil binding protein), and presents with increased levels of sterol precursors 8(9)-cholesterol and 8-dehydrocholesterol. OBJECTIVES: To expand the understanding of CDPX2, clinically, biochemically and genetically. METHODS: We present one of the largest series reported to date, including 13 female patients belonging to nine Spanish families. Patients were studied biochemically using gas chromatography-mass spectrometry, genetically using polymerase chain reaction and in their methylation status using the HUMARA assay. RESULTS: In our cases, there was a clear relationship between abnormal sterol profile and the EBP gene mutation. We describe three novel mutations in the EBP gene. EBP mutations were inherited in three out of nine families and were sporadic in the remaining cases. CONCLUSIONS: No clear genotype-phenotype correlation was found. Patients' biochemical profiles did not reveal a relationship between sterol profiles and severity of disease. A skewed X-chromosome inactivation may explain the clinical phenotype in CDPX2 in some familial cases.

Utilidad de los niveles de colestanol en el diagnóstico y seguimiento de los pacientes con xantomatosis cerebrotendinosa / Usefulness of cholestanol levels in the diagnosis and follow-up of patients with cerebrotendinous xanthomatosis

Introducción: la xantomatosis cerebro-tendinosa (XCT) es una enfermedad autosómica recesiva producida por un déficit de la enzima 27-hidroxilasa. Como consecuencia, existe una deficiencia de ácido quenodeoxicólico y una sobreproducción de colestanol que se deposita en los tejidos. Clínicamente cursa con cataratas, diarrea, xantomas y diferentes síntomas neurológicos. A pesar de que los niveles de colestanol se emplean en el diagnóstico de la XCT, se desconoce su correlación con la clínica y el pronóstico. Métodos: se han revisado 14 pacientes afectos de XCT, diagnosticados entre 1995 y 2008 en dos centros de referencia para el diagnóstico genético, en los que se había determinado el colestanol. Se han estudiado los principales datos demográficos, clínicos y terapéuticos y su posible relación con los niveles de colestanol. Resultados: la media de los niveles de colestanol al diagnóstico fue de 106μmol/ l. No se encontró ninguna relación entre el colestanol plasmático y los diferentes síntomas neurológicos, ni con el grado de discapacidad al diagnóstico medido mediante la EDSS. Tras la instauración del tratamiento se obtuvo una reducción significativa del colestanol plasmático en todos los casos (reducción media de 91μmol/ l en una media de 34 meses), a pesar de lo cual sólo un paciente se estabilizó clínicamente. Conclusiones: la presencia de niveles elevados de colestanol es muy útil para el diagnóstico de la XCT, pero no tiene valor pronóstico (no se correlaciona con la situación funcional). Su normalización no siempre se acompaña de una estabilización clínica, pero su monitorización puede ser útil para el ajuste del tratamiento (AU)

Introduction: cerebrotendinous xanthomatosis (CTX) is an autosomal recessive disease caused by a deficiency of mitochondrial enzyme sterol 27-hydrolylase. Such a deficiency results in a reduced production of chenodeoxycholic acid and in an increased formation of cholestanol. It is clinically characterized by cataracts, diarrhoea, xanthomas, premature arteriosclerosis and a number of progressive neurological symptoms. Although cholestanol levels are used for the diagnosis of CTX, their correlation with the clinical symptoms and their prognostic usefulness have not been assessed so far. Methods: we reviewed 14 CTX patients diagnosed between 1995 and 2008 in two reference centres for the genetic diagnosis of this disorder, whose cholestanol levels had been recorded. We studied the main demographic, clinical and therapeutical data and their correlation with plasma cholestanol levels. Results: the average cholestanol level at diagnosis was 105.8μmol/l. These levels did not correlate with any neurological symptoms or with disability at diagnosis scored by the EDSS. After treatment, all patients achieved a significant reduction in plasma cholestanol levels (average reduction of 91μmol/l in an average follow-up of 34 months), although only one patient remained clinically stable. Conclusions: high cholestanol levels are very useful for diagnosis of CTX but they do not have a prognostic value (they do not correlate with severity). Normalisation of cholestanol levels is not always associated with clinical stabilisation. However, follow-up of cholestanol levels can be useful for the dose adjustment (AU)

[Usefulness of cholestanol levels in the diagnosis and follow-up of patients with cerebrotendinous xanthomatosis]. / Utilidad de los niveles de colestanol en el diagnóstico y seguimiento de los pacientes con xantomatosis cerebrotendinosa.

INTRODUCTION: cerebrotendinous xanthomatosis (CTX) is an autosomal recessive disease caused by a deficiency of mitochondrial enzyme sterol 27-hydrolylase. Such a deficiency results in a reduced production of chenodeoxycholic acid and in an increased formation of cholestanol. It is clinically characterized by cataracts, diarrhoea, xanthomas, premature arteriosclerosis and a number of progressive neurological symptoms. Although cholestanol levels are used for the diagnosis of CTX, their correlation with the clinical symptoms and their prognostic usefulness have not been assessed so far. METHODS: we reviewed 14 CTX patients diagnosed between 1995 and 2008 in two reference centres for the genetic diagnosis of this disorder, whose cholestanol levels had been recorded. We studied the main demographic, clinical and therapeutical data and their correlation with plasma cholestanol levels. RESULTS: the average cholestanol level at diagnosis was 105.8 µmol/l. These levels did not correlate with any neurological symptoms or with disability at diagnosis scored by the EDSS. After treatment, all patients achieved a significant reduction in plasma cholestanol levels (average reduction of 91 µmol/l in an average follow-up of 34 months), although only one patient remained clinically stable. CONCLUSIONS: high cholestanol levels are very useful for diagnosis of CTX but they do not have a prognostic value (they do not correlate with severity). Normalisation of cholestanol levels is not always associated with clinical stabilisation. However, follow-up of cholestanol levels can be useful for the dose adjustment.

[Cerebrotendinous xanthomatosis: report of 4 patients]. / Xantomatosis cerebrotendinosa: descripción de 4 casos.

Cerebrotendinous xanthomatosis (CTX) is an uncommon autosomal recessive disease caused by mutation of the CYP27A1 gene. It is characterized by the presence of xanthomas in different tissues, principally brain and tendon, due to the accumulation of beta-cholestanol. Diagnosis is confirmed by measurement of serum beta-cholestanol and urinary bile alcohol levels. Therapy with chenodeoxycholic acid has been shown to be the most effective treatment and can halt progression of the disease. We present 4 patients with a history of neurological disorders since childhood and who were diagnosed with CTX after developing tendon xanthomas. Although diagnostic suspicion depends to a large extent on recognition of tendon xanthomas, these are not an early sign of the disease, which can present with neurological disorders, cataracts, and chronic diarrhea. Early diagnosis of CTX therefore rests on measurement of serum beta-cholestanol levels, even in absence of tendon xanthomas.

Xantomatosis cerebrotendinosa: descripción de 4 casos / Cerebrotendunous Xanthomatosis: report of 4 patients

La xantomatosis cerebrotendinosa (XCT) es una enfermedad hereditaria infrecuente causada por la mutación del gen CYP27A1. Es característica la aparición de xantomas en diferentes tejidos, principalmente en el cerebro y los tendones, secundarios al depósito de -colestanol. El diagnóstico se confirma mediante la determinación de -colestanol en suero, y de los alcoholes biliares en orina. El ácido quenodesoxicólico es la terapia más eficaz, pudiendo llegar a frenar la progresión de la enfermedad. Presentamos 4 pacientes con alteraciones neurológicas desde la infancia que fueron diagnosticados de XCT tras el desarrollo de xantomas tendinosos. El reconocimiento de los xantomas tendinosos es fundamental para orientar el diagnóstico de XCT, pero estos no son un signo inicial de la enfermedad, que debuta con alteraciones neurológicas, cataratas o diarrea crónica. Por lo tanto, el diagnóstico temprano de la XCT requiere la determinación del -colestanol sérico en estos pacientes, aun en ausencia de xantomas (AU)

Cerebrotendinous xanthomatosis (CTX) is an uncommon autosomal recessive disease caused by mutation of the CYP27A1 gene. It is characterized by the presence of xanthomas in different tissues, principally brain and tendon, due to the accumulation of -cholestanol. Diagnosis is confirmed by measurement of serum -cholestanol and urinary bile alcohol levels. Therapy with chenodeoxycholic acid has been shown to be the most effective treatment and can halt progression of the disease. We present 4 patients with a history of neurological disorders since childhood and who were diagnosed with CTX after developing tendon xanthomas. Although diagnostic suspicion depends to a large extent on recognition of tendon xanthomas, these are not an early sign of the disease, which can present with neurological disorders, cataracts, and chronic diarrhea. Early diagnosis of CTX therefore rests on measurement of serum -cholestanol levels, even in absence of tendon xanthomas (AU)

Adrenoleucodistrofia ligada al cromosoma X: diagnóstico olvidado en niños con enfermedad de Addison idiopática / X- linked Adrenoleukodystrophy: misdiagnosed disease in children with idiopathic Addison´s disease

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Calidad en genética bioquímica prenatal / Quality in prenatal biochemical genetics

Para diagnosticar enfermedades metabólicas hereditarias(EMH), tanto postnatales como prenatalmente, se empleanlos recursos de la genética bioquímica, que se basanmayoritariamente en el estudio en fluidos biológicos y tejidos de productos génicos (proteínas) y de metabolitos específicos que sean demostrativos o estén directamente relacionados con la pérdida de función de un gen. Las EMH, debido a sus bajas prevalencias individuales, entran en la categoría de enfermedades raras o minoritarias, pero se han descrito centenares de ellas y en general son enfermedades abrumadoras y a menudo letales. Debido a ello y a las dificultadesde tratamiento, su diagnóstico prenatal es muy relevante.En el presente artículo se resumen unos conocimientosmínimos indispensables sobre su complejidad y losmedios del laboratorio para llegar al diagnóstico, a fin de demostrar la importancia que tiene en el diagnóstico prenatal la labor de reunir la máxima información posible acerca del caso índice y de los padres (heterocigotos). Seguidamente se trata el tema de la calidad de los laboratorios y de laspruebas o ensayos de genética bioquímica, incluyendo elcontrol europeo específico de la ERNDIM, el proyecto Eurogentest de la CE para la armonización, validación y estandarización de pruebas genéticas, la Ley 14/2007 de 3 de julio de 2007 de investigación biomédica que define y regula el marco para la realización de pruebas genéticas en investigación y en asistencia y las Normas ISO para la certificación y acreditación de los laboratorios. El artículo finaliza con unrecordatorio de las técnicas y materiales fetales utilizados para el diagnóstico prenatal de las EMH

For the diagnosis of Inherited disorders of metabolism(IDM), postnatal as well as prenatal, we need the resources of Biochemical genetics, which are mainly based in the studies in biological fluids and tissues of the gene products (proteins) and specific metabolites, directly related or demonstratives of a gene function impairment. Because of the very low individual prevalence of IDM, they are consideredrare diseases, but it had been described hundreds ofthem, being moreover overwhelming and often lethal diseases. These facts, together with difficulties for treatment made prenatal diagnosis very relevant. In this paper, there are summarised some essential knowledge on the complexity of IDM and the resources of the laboratory for its diagnosis, in order to show how it is important for the prenatal diagnosis, to collect all the possible information about the index case and the parents (heterozygous). Next, issues are the quality of the biochemical genetics tests and laboratories,including the specific ERNDIM QAP; the FP6 projectEurogentest for the harmonization, validation andstandardization of diagnostic genetic testing; the Spanish bill 14/2007 on biomedical research, that among other issues provides for genetic testing for research as well as for medical care purposes and some concepts on ISO norms for the certification/accreditation of laboratories. Finally, there is a reminder of the technology and foetal materials suitable for the prenatal diagnosis of IDM

Age and origin of major Smith-Lemli-Opitz syndrome (SLOS) mutations in European populations.

BACKGROUND: Smith-Lemli-Opitz syndrome (SLOS) (MIM 270 400) is an autosomal recessive multiple congenital anomalies/mental retardation syndrome caused by mutations in the Delta7-sterol reductase (DHCR7, E.C.1.3.1.21) gene. The prevalence of SLOS has been estimated to range between 1:15000 and 1:60000 in populations of European origin. METHODS AND RESULTS: We have analysed the frequency, origin, and age of DHCR7 mutations in European populations. In 263 SLOS patients 10 common alleles (c.964-1G>C, p.Trp151X, p.Thr93Met, p.Val326Leu, p.Arg352Trp, p.Arg404Cys, p.Phe302Leu, p.Leu157Pro, p.Gly410Ser, p.Arg445Gln) were found to constitute approximately 80% of disease-causing mutations. As reported before, the mutational spectra differed significantly between populations, and frequency peaks of common mutations were observed in North-West (c.964-1G>C), North-East (p.Trp151X, p.Val326Leu) and Southern Europe (p.Thr93Met). SLOS was virtually absent from Finland. The analysis of nearly 8000 alleles from 10 different European populations confirmed a geographical distribution of DHCR7 mutations as reported in previous studies. The common Null mutations in Northern Europe (combined ca. 1:70) occurred at a much higher frequency than expected from the reported prevalence of SLOS. In contrast the most common mutation in Mediterranean SLOS patients (p.Thr93Met) had a low population frequency. Haplotypes were constructed for SLOS chromosomes, and for wild-type chromosomes of African and European origins using eight cSNPs in the DHCR7 gene. The DHCR7 orthologue was sequenced in eight chimpanzees (Pan troglodytes) and three microsatellites were analysed in 50 of the SLOS families in order to estimate the age of the three major SLOS-causing mutations. CONCLUSIONS: The results indicate a time of first appearance of c.964-1G>C and p.Trp151X some 3000 years ago in North-West and North-East Europe, respectively. The p.Thr93Met mutations on the J haplotype has probably first arisen approximately 6000 years ago in the Eastern Mediterranean. Together, it appears that a combination of founder effects, recurrent mutations, and drift have shaped the present frequency distribution of DHCR7 mutations in Europe.

Mutational spectrum of classical galactosaemia in Spain and Portugal.

Classical galactosaemia is an autosomal recessive inherited metabolic disorder due to deficient galactose-1-phosphate uridyltransferase (GALT). Over 180 different base changes and disease-causing mutations have been reported in the GALT gene. Mutation p.Q188R was found to be the most common molecular defect among caucasian classical galactosaemia patients. We have characterized the spectrum of GALT mutations in a group of 51 Spanish families and 32 Portuguese families with this disease. p.Q188R is also the most prevalent mutation in the Spanish and Portuguese population, accounting for 50% and 57.8% of galactosaemic alleles, respectively. An additional 15 mutations were also identified in Spanish patients, four of which were novel: p.D28H, p.S181A, c.658dupG and c.377+53_1059+87del. In the Portuguese population, 11 different mutations were found, three of which were novel: p.R33H, p.P185S, and p.S192G. The differences observed between the genotypes identified in Portuguese and Spanish galactosaemic populations are notable. Only mutations p.Q188R, p.R148Q and c.820+13g>a were identified in both populations. In spite of the geographical proximity of Spain and Portugal, it seems that they have received genetic influences from different populations. The repeated migrations that occurred in the Iberian Peninsula throughout centuries may explain such variability.

X-linked adrenoleukodystrophy in Spain. Identification of 26 novel mutations in the ABCD1 gene in 80 patients. Improvement of genetic counseling in 162 relative females.

In this study, we analyzed the ABCD1 gene in 80 X-linked adrenoleukodystrophy (X-ALD) patients from 62 unrelated families. We identified 53 different mutations, of which 26 are novel and two are non-pathogenic sequence variants (L516L and 3'UTR, 2246C/G) that have been previously described. The Spanish population had significant allelic heterogeneity, in which most of the mutations were exclusive to a single family 47/53 (88.7%). Only six mutations (Y174S, G277R, FsE471, R518Q, P543L, and R554H) were found in more than one family. Mutations G277R, P543L, and R554H were the most frequent, each of them being found in three patients (5%). Intra-familiar phenotype variability was observed in most of the families, but in one, with the novel mutation R120P, only the adult mild phenotype was present (five hemizygous family members). We detected 80 heterozygous women by mutation analysis, but only 78 of them showed increased very-long-chain fatty acid levels. In conclusion, this study extends the spectrum of mutations in X-ALD and facilitates the identification of heterozygous females. Our results are also consistent with previous studies reporting the difficulty of predicting genotype-phenotype correlation.

Maternal apo E genotype is a modifier of the Smith-Lemli-Opitz syndrome.

BACKGROUND: Smith-Lemli-Opitz syndrome (MIM 270400) is an autosomal recessive malformation and mental retardation syndrome that ranges in clinical severity from minimal dysmorphism and mild mental retardation to severe congenital anomalies and intrauterine death. Smith-Lemli-Opitz syndrome is caused by mutations in the Delta7 sterol-reductase gene (DHCR7; EC 1.3.1.21), which impair endogenous cholesterol biosynthesis and make the growing embryo dependent on exogenous (maternal) sources of cholesterol. We have investigated whether apolipoprotein E, a major component of the cholesterol transport system in human beings, is a modifier of the clinical severity of Smith-Lemli-Opitz syndrome. METHOD: Common apo E, DHCR7, and LDLR genotypes were determined in 137 biochemically characterised patients with Smith-Lemli-Opitz syndrome and 59 of their parents. RESULTS: There was a significant correlation between patients' clinical severity scores and maternal apo E genotypes (p = 0.028) but not between severity scores and patients' or paternal apo E genotypes. In line with their effects on serum cholesterol levels, the maternal apo epsilon2 genotypes were associated with a severe Smith-Lemli-Opitz syndrome phenotype, whereas apo E genotypes without the epsilon2 allele were associated with a milder phenotype. The correlation of maternal apo E genotype with disease severity persisted after stratification for DHCR7 genotype. There was no association of Smith-Lemli-Opitz syndrome severity with LDLR gene variation. CONCLUSIONS: These results suggest that the efficiency of cholesterol transport from the mother to the embryo is affected by the maternal apo E genotype and extend the role of apo E and its disease associations to modulation of embryonic development and malformations.

[Zellweger syndrome. Reports on two new cases]. / Síndrome de Zellweger. Presentación de dos nuevos casos.

INTRODUCTION: Zellweger syndrome, or cerebrohepatorenal syndrome, is the most serious form of the peroxisomal diseases. Clinically, it is characterised by the association between craniofacial dysmorphia and neurological disorders, together with the involvement of other organs. To perform a diagnosis it is advisable to follow a procedural protocol that begins with the quantification of very long chain fatty acids in an assortment of samples (serum, fibroblasts and mononucleate cells), plasmalogens, branched chain fatty acids in serum (phytanic and pristanic acids), polyunsaturated acids and bile salts. Studies conducted with neuroimaging, renal echography, skeletal X rays and biopsy samples of different tissues will provide us with information about the involvement of different organs. CASE REPORTS: The first case we report is that of a male who, from birth, presented a distinctive phenotype with very large fontanelles, important hypotonia, epileptic seizures and acute organic disorders that led to death at the age of seven weeks. The second case involved a new born male suffering from prenatally diagnosed heart disease and craniofacial dysmorphia with hypotonia. CONCLUSIONS: Given the scarce survival rate of patients, early diagnosis of this type of disease is crucial and, although complex, a study must be conducted so as to be able to provide genetic counselling.

Síndrome de Zellweger. Presentación de dos nuevos casos / Zellweger syndrome. Reports on two new cases

Introducción. El síndrome de Zellweger o síndrome cerebro hepatorrenales la forma más grave de las enfermedades peroxisomales. Clínicamente, se caracteriza por la asociación de dismorfia craneofacial y alteraciones neurológicas, junto con la afectación de otros órganos. Para realizar el diagnóstico es conveniente recurrir a un protocolo de actuación que comienza con la cuantificación de los ácidos grasos de cadena muy larga en diversas muestras (suero,fibroblastos y células mononucleadas), plasmalógenos, ácidos ramificados en el suero (ácidos fitánico y pristánico), ácidos poliinsaturados y sales biliares; continúa con los estudios de neuroimagen, ecografía renal, radiografías de esqueleto, y concluye con la toma de muestras mediante biopsia de diversos tejidos, que nos aportará información acerca de la afectación de distintos órganos. Casos clínicos. Presentamos un primer caso de un varón que ya desde el nacimiento presenta un fenotipo peculiar, con fontanelas muy amplias, hipotonía grave, crisis epilépticas y agudas alteraciones orgánicas que condujeron al fallecimiento a las siete semanas de vida. El segundo caso corresponde a un recién nacido varón afectado de una cardiopatía diagnosticada prenatalmente y dismorfia craneofacial con hipotonía. Conclusiones.El diagnóstico precoz de este tipo de enfermedades es crucial, dada la escasa supervivencia de los pacientes y la necesidad de realizar un estudio que, a pesar de resultar complejo, es necesario para poder ofrecer un consejo genético (AU)

[Mutation P28T in gene GK1 as the cause of a familial galactokinase deficiency]. / La mutación P28T del gen GK1 como causa de una deficiencia familiar de galactoquinasa.

OBJECTIVE/METHOD: To alert about galactokinase deficiency (GK) as a possible cause of infantile cataracts, and even presenile cataracts in heterozygous carriers. Diagnosis by enzyme and galactitol determination would lead to the introduction of a galactose-free diet which completely prevents the damage. RESULT/CONCLUSIONS: We report on a highly consanguineous Spanish family of gypsy ethnia, with three females of different sibships affected by GK deficiency. The deficiency was due to their homozygosis for mutation P28T in gene GK1. P28T mutation in european Romani gypsies, is also present in Spanish gypsies. It is important to bear in mind that GK deficiency may be an important cause of blindness in that endogamous group.

La mutación P28T del gen GK1 como causa de una deficiencia familiar de galactoquinasa / Mutation P28T in gene GK1 as the cause of a familial galactokinase deficiency

Objetivo/Método: Alertar sobre la deficiencia de galactoquinasa (GK), como posible causa de cataratas infantiles, e incluso cataratas preseniles en los heterozigotes portadores. El diagnóstico mediante determinación del enzima y del galactitol, permitiría la introducción de una dieta exenta de galactosa que previene totalmente el daño. Resultado/Conclusiones: Presentamos una familia española de etnia gitana con alto grado de consanguinidad con tres hembras, de fratrias distintas, afectas de deficiencia de GK. La deficiencia es debida a su homozigosis para la mutación P28T del gen GK1. P28T, con efecto fundador en gitanos Romani europeos, está también presente en los gitanos españoles. Por ello hay que tener en cuenta que la deficiencia de GK puede ser causa importante de ceguera en dicha población (AU)

Objective/Method: To alert about galactokinase deficiency (GK) as a possible cause of infantile cataracts, and even presenile cataracts in heterozygous carriers. Diagnosis by enzyme and galactitol determination would lead to the introduction of a galactose-free diet which completely prevents the damage. Result/Conclusions: We report on a highly consanguineous Spanish family of gypsy ethnia, with three females of different sibships affected by GK deficiency. The deficiency was due to their homozygosis for mutation P28T in gene GK1. P28T mutation in european Romani gypsies, is also present in Spanish gypsies. It is important to bear in mind that GK deficiency may be an important cause of blindness in that endogamous group (AU)

[Cerebrotendinous xanthomatosis without tendinous xanthomas: presentation of two cases]. / Xantomatosis cerebrotendinosa sin xantomas tendinosos: presentación de dos casos.

Cerebrotendinous xanthomatosis (CTX) is a genetic disorder caused by a 27-hydroxilase enzyme deficiency, leading to beta-cholestanol storage in many body tissues. Clinically, the disease is characterised by the presence of tendinous xanthomas, juvenile cataracts and progressive neurologic dysfunction. The diagnosis requires beta-cholestanol quantification in serum. We report two siblings with a history of photosensitive epilepsy of childhood onset, who developed progressive spastic paraparesis and cataracts in their third decade of life. They were diagnosed to have CTX in spite of the absence of tendinous xanthomas. Cranial and spinal MRI only showed bilateral high intensity signal in the dentate nuclei in the T2-weighted and proton-density sequences. Our patients presented with a progressive spastic paraparesis. The delay in the diagnosis in our case could be due to the absence of tendinous xanthomas and late-onset cataracts. The recognition of the disease is important, because the treatment with chenodeoxycholic acid induces a decrement of beta-cholestanol levels in serum and could prevent the progression of the disease.