Severe neurological abnormalities in a young boy with impaired thyroid hormone sensitivity due to a novel mutation in the MCT8 gene.

Monocarboxylate transporter 8 (MCT8) is an active and specific thyroid hormone transporter into neurons. MCT8 mutations cause an X-linked condition known as Allan-Herndon-Dudley syndrome and are characterized by impaired psychomotor development and typical abnormal thyroid function. We describe a 10-year-old boy with severe cognitive disability, axial hypotonia, spastic quadriplegia and sporadic dyskinetic episodes. He initially presented with thyroid dysfunction (high FT3, low rT3, low FT4 and normal TSH) and generalized retardation of the cerebral and cerebellar myelination in brain magnetic resonance imaging. The clinical and laboratory findings led to sequencing of the SLC16A2/MCT8 gene, which identified a novel missense mutation in exon 5. The study of peripheral markers of thyroid function suggests a paradoxical state of thyrotoxicosis in some peripheral tissues. Our patient had a typical clinical presentation at birth but because of the rarity of his disease his diagnosis was not made until the age of 7. The delay can also be explained by the omission of the free T3 assay in the first thyroid evaluation performed. This case therefore highlights the possible benefit of including the T3 assay in the study of patients with severe psychomotor disability of unknown etiology, thus eliminating extra costs for unnecessary complementary diagnostic tests.

Copy number variation analysis of patients with intellectual disability from North-West Spain.

Intellectual disability (ID) is a complex and phenotypically heterogeneous neurodevelopmental disorder characterized by significant deficits in cognitive and adaptive skills, debuting during the developmental period. In the last decade, microarray-based copy number variation (CNV) analysis has been proved as a strategy particularly useful in the discovery of loci and candidate genes associated with these phenotypes and is widely used in the clinics with a diagnostic purpose. In this study, we evaluated the usefulness of two genome-wide high density SNP microarrays -Cytogenetics Whole-Genome 2.7M SNP array (n=126 patients; Group 1) and CytoScan High-Density SNP array (n=447 patients; Group 2)- in the detection of clinically relevant CNVs in a cohort of ID patients from Galicia (NW Spain). In 159 (27.7%) patients, we detected 186 rare exonic chromosomal imbalances, that were grouped into the following classes: Clinically relevant (67/186; 36.0%), of unknown clinical significance (93/186; 50.0%) and benign (26/186; 14.0%). The 67 pathogenic CNVs were identified in 64 patients, which means an overall diagnostic yield of 11.2%. Overall, we confirmed that ID is a genetically heterogeneous condition and emphasized the importance of using genome-wide high density SNP microarrays in the detection of its genetic causes. Additionally, we provided clinical and molecular data of patients with pathogenic or likely pathogenic CNVs and discussed the potential implication in neurodevelopmental disorders of genes located within these variants.

Articular manifestations in patients with Lyme disease. / Manifestaciones articulares en enfermos de Lyme.

OBJECTIVES: To determine the percentage of Lyme patients with articular manifestations in NW Spain and to know their evolution and response to treatment. PATIENTS: A retrospective study (2006-2013) was performed using medical histories of confirmed cases of Lyme disease showing articular manifestations. Clinical and laboratory characteristics, together with the treatment and evolution of the patients, were analysed. RESULTS: Seventeen out of 108 LD confirmed patients (15.7%) showed articular manifestations. Regarding those 17 patients, 64.7%, 29.4% and 5.9% presented arthritis, arthralgia and bursitis, respectively. The knee was the most affected joint. Articular manifestations were often associated to neurological, dermatological and cardiac pathologies. Otherwise, most patients were in Stage III. The 11.8% of the cases progressed to a recurrent chronic arthritis despite the administration of an appropriate treatment. CONCLUSIONS: Lyme disease patients showing articular manifestations should be included in the diagnosis of articular affections in areas of high risk of hard tick bite, in order to establish a suitable and early treatment and to avoid sequels.

Congenital neurogenic muscular atrophy in megaconial myopathy due to a mutation in CHKB gene.

Choline kinase beta gene (CHKB) mutations have been identified in Megaconial Congenital Muscular Dystrophy (MDCMC) patients, a very rare inborn error of metabolism with 21 cases reported worldwide. We report the case of a Spanish boy of Caucasian origin who presented a generalized congenital muscular hypotonia, more intense at lower limb muscles, mildly elevated creatine kinase (CK), serum aspartate transaminase (AST) and lactate. Electromyography (EMG) showed neurogenic potentials in the proximal muscles. Histological studies of a muscle biopsy showed neurogenic atrophy with enlarged mitochondria in the periphery of the fibers, and complex I deficiency. Finally, genetic analysis showed the presence of a homozygous mutation in the gene for choline kinase beta (CHKB: NM_005198.4:c.810T>A, p.Tyr270(∗)). We describe here the second Spanish patient whit mutation in CHKB gene, who despite having the same mutation, presented an atypical aspect: congenital neurogenic muscular atrophy progressing to a combined neuropathic and myopathic phenotype (mixed pattern).

Interstitial microdeletions including the chromosome band 4q13.2 and the UBA6 gene as possible causes of intellectual disability and behavior disorder.

The few proximal 4q chromosomal aberrations identified in patients with neurodevelopmental phenotypes that have been published to date are variable in type, size and breakpoints and, therefore, encompass different chromosome bands and genes, making the establishment of genotype-phenotype correlations a challenging task. Here, microarray-based copy number analysis allowed us the detection of two novel and partially overlapping deletions in two unrelated families. In Family 1, a 4q13.1-q13.2 deletion of 3.84 Mb was identified in a mother with mild intellectual disability and in her two children, both with mild intellectual disability and attention deficit hyperactivity disorder. In Family 2, a de novo 4q13.2-q13.3 deletion of 6.81 Mb was detected in a female patient, born to unaffected parents, with a diagnosis of mild intellectual disability, behavioral disorder and facial dysmorphism. The shortest region of overlap between these two aberrations is located at chromosome 4q13.2 and includes 17 genes amongst of which we suggest UBA6 (ubiquitin-like modifier-activating enzyme 6) as a strong candidate gene for these phenotypes.

Clinical characterization of a male patient with the recently described 8q21.11 microdeletion syndrome.

The 8q21.11 microdeletion syndrome (OMIM # 614230) has been recently described and is primarily characterized by intellectual disability and facial dysmorphism. We describe here a male patient of 9 years 9 months of age with moderate intellectual disability and dysmorphic facial features. A high resolution copy number variation analysis, performed with the Affymetrix Cytogenetics Whole-Genome 2.7 M SNP array, allowed the identification of a heterozygous 7.069 Mb microdeletion at chromosome 8q21.11-q21.13. Clinical comparison of our patient with literature shows many similarities. However, the whole facial appearance of our patient, especially the elongated rather than rounded face and the absence of a wide nasal bridge and epicanthal folds, confers him a phenotype similar only to a subset, but not to the majority, of the hitherto described patients.

A maternally inherited 16p13.11-p12.3 duplication concomitant with a de novo SOX5 deletion in a male patient with global developmental delay, disruptive and obsessive behaviors and minor dysmorphic features.

We detail here the clinical description and the family genetic study of a male patient with global developmental delay, disruptive and obsessive behaviors and minor dysmorphic features and a combination of two rare genetic variants: a maternally inherited 16p13.11-p12.3 duplication and a de novo 12p12.1 deletion affecting SOX5. The 16p13.11 microduplication has been implicated in several neurodevelopmental and behavioral disorders and is characterized by variable expressivity and incomplete penetrance. The causes of this variation in phenotypic expression are not fully clear, representing a challenge in genetic diagnosis and counseling. However, several authors have proposed the two-hit model as one of the underlying mechanisms for this phenotypic heterogeneity. Our data could also support this two-hit model in which the 16p13.11-p12.3 duplication might contribute to the phenotype, not only as a single event but also in association with the SOX5 deletion. The SOX5 gene plays important roles in various developmental processes and has been associated with several neurodevelopmental disorders, mainly intellectual disability, developmental delay and language and/or speech delay as well as with behavior problems and dysmorphic features. However, many of the physical features and behavioral manifestations as well as language deficiencies present in our patient are consistent with those previously reported for SOX5 deletions. Patients carrying multiple genomic variants, as the one presented here, illustrate the difficulty in analyzing genotypes when the contribution of each variant results in overlapping phenotypes and/or, alternatively, in the modification of the clinical manifestations defined by the coexisting variant.

[Epidemiology of Lyme disease in a healthcare area in north-west Spain]. / Epidemiología de la enfermedad de Lyme en un área sanitaria del noroeste de España.

OBJECTIVE: To evaluate the influence of some risk factors on the incidence rate of Lyme disease and the main clinical manifestations. METHODS: A retrospective study of Lyme disease (2006-2013) was performed in north-west Spain; we included only patients who fulfilled the epidemiological surveillance criteria defined by the Centers for Disease Control and Prevention. RESULTS: The incidence rate varied between 2.64 and 11.61/100,000 inhabitants/year. Significant differences were found in relation to habitat, age and area of residence. Patients showed neurological (67.59%), dermatological (47.22%), rheumatological (15.74%) and cardiac (13.88%) manifestations, alone or combined. CONCLUSIONS: Due to the increase of the disease in north-west Spain and the differences observed between the different areas, epidemiological studies are needed that increase the index of diagnostic suspicion and lead to the implementation of effective prevention measures.

Characterization of human disease phenotypes associated with mutations in TREX1, RNASEH2A, RNASEH2B, RNASEH2C, SAMHD1, ADAR, and IFIH1.

Aicardi-Goutières syndrome is an inflammatory disease occurring due to mutations in any of TREX1, RNASEH2A, RNASEH2B, RNASEH2C, SAMHD1, ADAR or IFIH1. We report on 374 patients from 299 families with mutations in these seven genes. Most patients conformed to one of two fairly stereotyped clinical profiles; either exhibiting an in utero disease-onset (74 patients; 22.8% of all patients where data were available), or a post-natal presentation, usually within the first year of life (223 patients; 68.6%), characterized by a sub-acute encephalopathy and a loss of previously acquired skills. Other clinically distinct phenotypes were also observed; particularly, bilateral striatal necrosis (13 patients; 3.6%) and non-syndromic spastic paraparesis (12 patients; 3.4%). We recorded 69 deaths (19.3% of patients with follow-up data). Of 285 patients for whom data were available, 210 (73.7%) were profoundly disabled, with no useful motor, speech and intellectual function. Chilblains, glaucoma, hypothyroidism, cardiomyopathy, intracerebral vasculitis, peripheral neuropathy, bowel inflammation and systemic lupus erythematosus were seen frequently enough to be confirmed as real associations with the Aicardi-Goutieres syndrome phenotype. We observed a robust relationship between mutations in all seven genes with increased type I interferon activity in cerebrospinal fluid and serum, and the increased expression of interferon-stimulated gene transcripts in peripheral blood. We recorded a positive correlation between the level of cerebrospinal fluid interferon activity assayed within one year of disease presentation and the degree of subsequent disability. Interferon-stimulated gene transcripts remained high in most patients, indicating an ongoing disease process. On the basis of substantial morbidity and mortality, our data highlight the urgent need to define coherent treatment strategies for the phenotypes associated with mutations in the Aicardi-Goutières syndrome-related genes. Our findings also make it clear that a window of therapeutic opportunity exists relevant to the majority of affected patients and indicate that the assessment of type I interferon activity might serve as a useful biomarker in future clinical trials.

Exome sequencing identifies a CHKB mutation in Spanish patient with megaconial congenital muscular dystrophy and mtDNA depletion.

BACKGROUND: Choline kinase beta gene (CHKB) mutations have been identified in Megaconial Congenital Muscular Dystrophy (MDCMC) patients, but never in patients with an additional combined deficiency of complexes I, III and IV and mitochondrial DNA (mtDNA) depletion. AIMS: To report mutations in carry genes for MDCMC with respiratory chain defects and mtDNA depletion. METHODS: Whole-exome sequencing (WES) was used to identify the carry genes in a Spanish child with muscle weakness, mild hypotonia at lower limb muscles, mildly elevated creatine kinase (CK), enlarged mitochondria in the periphery of the fibers, combined deficiency of complex I, III and IV and depletion of mtDNA. RESULTS: With WES data, it was possible to get the whole mtDNA sequencing and discard any pathogenic variant in this genome. The first filter of WES data with the nuclear-encoded mitochondrial genes (MitoCarta) did not get any candidate. However, the analysis of whole exome uncovered a homozygous nonsense pathogenic mutation in CHKB gene (NM_005198.4:c.810T>A, p.Tyr270*). CONCLUSIONS: Our data confirm the role of CHKB in MDCMC and point to this gene as unique candidate for the combined deficiency of respiratory chain and mtDNA depletion observed in this patient.

Assessment of a targeted resequencing assay as a support tool in the diagnosis of lysosomal storage disorders.

BACKGROUND: With over 50 different disorders and a combined incidence of up to 1/3000 births, lysosomal storage diseases (LSDs) constitute a major public health problem and place an enormous burden on affected individuals and their families. Many factors make LSD diagnosis difficult, including phenotype and penetrance variability, shared signs and symptoms, and problems inherent to biochemical diagnosis. Developing a powerful diagnostic tool could mitigate the protracted diagnostic process for these families, lead to better outcomes for current and proposed therapies, and provide the basis for more appropriate genetic counseling. METHODS: We have designed a targeted resequencing assay for the simultaneous testing of 57 lysosomal genes, using in-solution capture as the enrichment method and two different sequencing platforms. A total of 84 patients with high to moderate-or low suspicion index for LSD were enrolled in different centers in Spain and Portugal, including 18 positive controls. RESULTS: We correctly diagnosed 18 positive blinded controls, provided genetic diagnosis to 25 potential LSD patients, and ended with 18 diagnostic odysseys. CONCLUSION: We report the assessment of a next-generation-sequencing-based approach as an accessory tool in the diagnosis of LSDs, a group of disorders which have overlapping clinical profiles and genetic heterogeneity. We have also identified and quantified the strengths and limitations of next generation sequencing (NGS) technology applied to diagnosis.

Glutaric aciduria type I: outcome of patients with early- versus late-diagnosis.

Patients with Glutaric aciduria type 1 (GA-1) can be identified by newborn screening using tandem mass spectrometry. The clinical evolution of screened patients seems to be more favourable compared with those diagnosed later, although long-term evolution is still doubtful. We have evaluated the outcome in nine GA-1 patients diagnosed in our region during 12 years. Six were detected by newborn screening and 3 clinically. The birth prevalence was 1:35,027. High blood C5DC concentration, in 8/9 patients, was found, whereas all patients exhibited high concentration of this metabolite in urine. Therefore, urine C5DC was a good marker for the detection of this disease. Eight different mutations in the GCDH gene were identified, four of them were novel (p.R88H, p.Y398C, p.R372K, p.D220N); being p.R227P the mostcommon. Macrocephaly with enlarged frontotemporal subarachnoid space was present in 4/6 patients diagnosed by newborn screening, all these patients required high energy intake, and in two cases, enteral feeding during the first year of life was needed. One child had an intercurrent episode of feeding refuse with hypoglycemia at two years of age. The mean follow-up time of screened patients was 56 months, and patients still remain asymptomatic. However, after a mean follow-up of 97 months treatment efficacy was poor in unscreened patients, two of them showing a severe spastic tetraparesis. Plasma levels of lysine, tryptophan and carnitine, were the most useful biomarkers for the follow-up. Our data support that, early diagnosis and treatment strategies are essential measures for the good clinical evolution of GA-1 patients.