Effects of SPTA1 Gene Variants on the Hematological Phenotype of Mexican Patients with Hereditary Spherocytosis.

Introduction: Hereditary spherocytosis (HS) is a common hereditary hemolytic anemia characterized by chronic hemolysis, increased indirect serum bilirubin, the presence of reticulocytes and spherocytes in blood smears, and great heterogeneity at the clinical, biochemical, and molecular levels. The molecular pathology of HS includes genetic variants at five genes: ANK1, EPB42, SLC4A1, SPTA1, and SPTB. Alpha spectrin (SPTA1) deficiency is the second leading cause of HS in Mexican patients. Aim: To assess the effects of five SPTA1 variants on the hematological phenotype of Mexican patients with HS. Materials and Methods: This study included a retrospective cohort of 227 biologically unrelated patients with HS. Variants c.4339-99C>T and c.6531-12C>T in SPTA1 were identified by the amplification-refractory mutation system polymerase chain reaction (ARMS-PCR), and variants c.5572C>T, c.5992C>G, and c.6794T>C were identified by quantitive Real Time-Polymerase Chain Reaction (qRT-PCR) allelic discrimination. Risk tests were performed for each variant with respect to HS clinical severity. Results: The SPTA1 c.5992C>G variant showed association with moderately severe HS (p = 0.006, odds ratio = 5.67, confidence interval95% = 1.6-19.9); the risk increased when the variant was in compound heterozygosity with αLELY and c.6794T>C. Lower hematological levels were observed in simple αLely (c.5572C>T and c.6531-12C>T), and c.5992C>G heterozygotes (red blood cell [RBC] p = 0.028 and 0.010; hemoglobin [Hb] p = 0.030 and 0.002; packed cell volume [PCV] p = 0.034 and 0.002 respectively), and in c.5992C>G+c.6794T>C compound heterozygotes (RBC p = 0.043; Hb p = 0.033; PCV p = 0.043). Additional genetic traits were observed: 15% had HS+Gilbert syndrome and 13% HS+thalassemia. Conclusion: Although most of the studied variants are considered benign, we observed significant associations with phenotypic severity. Therefore, we recommend the inclusion of these variants in molecular screening for HS.

Causas del hidrops fetal: experiencia en un hospital obstétrico del Occidente de México / Etiology of fetal hydrops: experience in an obstetric hospital in western Mexico

Resumen OBJETIVO: Identificar las causas de hidrops fetal no inmunitario en un hospital obstétrico de referencia del Occidente de México. MATERIALES Y MÉTODOS: Estudio de serie de casos, con un muestreo no probabilístico por conveniencia, llevado a cabo de octubre de 2014 a septiembre de 2015 al que se incluyeron pacientes (entre las 15 y 38 semanas de embarazo), mayores de edad (en casos de menores de edad se solicitó consentimiento informado a los padres o tutores), con diagnóstico de hidrops fetal por ultrasonido obstétrico. Para el análisis estadístico se generó una base de datos en Excel y se aplicó estadística descriptiva. RESULTADOS: Se reunieron 33 embarazadas en quienes el hidrops fetal no inmunitario fue el más frecuente (n = 31) y la causa idiopática más común (n = 10) seguida por errores innatos del metabolismo, alteraciones cromosómicas y cardiacas (n = 6 de cada una). Posteriormente, las causas hematológicas (n = 4), linfáticas y sindrómicas (n = 3 de cada una), y las infecciosas y tumorales (n = 1 de cada una). En este estudio los errores innatos del metabolismo (específicamente síndrome Sly) tuvieron una frecuencia superior a la referida en la bibliografía. CONCLUSIONES: Los errores innatos del metabolismo, las anomalías cromosómicas y cardiacas fueron la segunda causa más frecuente de hidrops fetal no inmunitario. Se sugiere tener en cuenta las causas metabólicas en el enfoque diagnóstico del hidrops fetal, sobre todo para el establecimiento del tratamiento temprano.

Abstract OBJECTIVE: To identify the causes of nonimmune fetal hydrops fetalis in an obstetric referral hospital in Western Mexico. MATERIALS AND METHODS: Case series study, with non-probabilistic sampling by convenience, carried out from October 2014 to September 2015 which included patients (between 15 and 38 weeks of pregnancy), of legal age (in cases of minors, informed consent was requested from parents or guardians), with a diagnosis of fetal hydrops fetalis by obstetric ultrasound. For statistical analysis, an Excel database was generated and descriptive statistics were applied. RESULTS: Thirty-three pregnant women were included, in whom non-immune fetal hydrops fetalis was the most frequent (94%) and idiopathic was the most common cause (n = 10), followed by inborn errors of metabolism, chromosomal and cardiac alterations (n = 6 each). This was followed by hematologic (n = 4), lymphatic and syndromic causes (n = 3 each), and infectious and tumor causes (n = 1 each). In this study, inborn errors of metabolism (specifically Sly syndrome) had a higher frequency than that reported in the literature. CONCLUSIONS: Inborn errors of metabolism, chromosomal and cardiac abnormalities were the second most frequent cause of nonimmune fetal hydrops. It is suggested that metabolic causes be taken into account in the diagnostic approach to fetal hydrops, especially for the establishment of early treatment.

Clinical Exome Sequencing Enables Congenital Sialidosis Type II Diagnosis in Two Siblings Presenting with Unreported Clinical Features from a Rare Homozygous Sequence Variant p.(Tyr370Cys) in NEU1.

Sialidosis is a rare autosomal recessive disease that presents with progressive lysosomal storage of sialylated glycopeptides and oligosaccharides caused by homozygous or compound heterozygous sequence variants in the neuraminidase 1 (NEU1) gene. These sequence variants can lead to sialidosis type I and II; the latter is the most severe and presents prenatally or at early age. However, sialidosis diagnosis is challenging, especially in those health systems with limited resources of developing countries. Consequently, it is necessary to dip into high-throughput molecular diagnostic tools to allow for an accurate diagnosis with better cost-effectiveness and turnaround time. We report a 4-member pedigree segregating an ultrarare missense variant, c.1109A>G; p.Tyr370Cys, in NEU1 as detected by whole-exome sequencing. Two short-lived siblings, who presented with previously unreported clinical features from such a homozygous sequence variant, were diagnosed with sialidosis type II. Additionally, we present a novel molecular model exhibiting the consequences of the variant in the sialidase-1 tridimensional structure. This study allowed us to provide a definitive diagnosis for our patients, increase our understanding of this pathogenic variant, and improve genetic counseling.

Microcephaly, an etiopathogenic vision.

Microcephaly is defined by an occipital-frontal head circumference (OFD) 2 standard deviations (SD) smaller than the average expected for age, gender and population. Its incidence has been reported between 1.3 and 150 cases per 100,000 births. Currently, new clinical characteristics, causes and pathophysiological mechanisms related to microcephaly continue to be identified. Its etiology is varied and heterogeneous, with genetic and non-genetic factors that produce alterations in differentiation, proliferation, migration, repair of damage to deoxyribonucleic acid and neuronal apoptosis. It requires a multidisciplinary diagnostic approach that includes a medical history, detailed prenatal and postnatal clinical evaluation, cerebral magnetic resonance imaging, neuropsychological evaluation, and in some cases complementary tests such as metabolic screening, tests to rule out infectious processes and genetic testing. There is no specific treatment or intervention to increase cerebral growth; however, timely intervention strategies and programs can be established to improve motor and neurocognitive development, as well as to provide genetic counseling. The objective of this work is to review the available information and reinforce the proposal to carry out an etiopathogenic approach for microcephaly diagnosis and management.

Whole-exome sequencing in three children with sporadic Blau syndrome, one of them co-presenting with recurrent polyserositis.

Blau syndrome (BS) is a rare, chronic autoinflammatory disease with onset before age 4 and mainly characterised by granulomatous arthritis, recurrent uveitis, and skin rash. Sporadic (also known as early-onset sarcoidosis) or familial BS is caused by gain-of-function mutations in the NOD2 gene, which encodes for a multi-task protein that plays a crucial role in the innate immune defense. We report on three Mexican patients clinically diagnosed with BS who exhibited a likely pathogenic variant in NOD2 as revealed by whole-exome sequencing (WES) and Sanger sequencing: two variants (c.1000 C > T/p.Arg334Trp and c.1538 T > C/p.Met513Thr) lie in the ATP/Mg2+ binding site, whereas the other (c.3019dupC/p.Leu1007ProfsTer2) introduces a premature stop codon disrupting the last LRR domain (LRR9) formation; all three variants are consistent with gain-of-function changes. Interestingly, all these patients presented concomitant likely pathogenic variants in other inflammatory disease-related genes, i.e. TLR10, PRR12, MEFV and/or SLC22A5. Although the clinical presentation in these patients included the BS diagnostic triad, overall it was rather heterogeneous. It is plausible that this clinical variability depends partly on the patients' genetic background as suggested by our WES results. After this molecular diagnosis and given the absence of NOD2 mutations (demonstrated in two trios) and related symptoms in the respective parents (confirmed in all trios), patients 1 and 2 were considered to have sporadic BS, while patient 3, a sporadic BS-recurrent polyserositis compound phenotype. Altogether, our observations and findings underscore the overlapping among inflammatory diseases and the importance of determining the underlying genetic cause by high-throughput methods. Likewise, this study further reinforces a pathogenic link between the here found NOD2 variants and BS and envisages potential additive effects from other loci in these, and probably other patients.

Severe Craniofacial Involvement due to Amniotic Band Sequence.

BACKGROUND: Disruptive amniotic band sequence (DABS) is a sporadic, non-familial disorder with unclear etiology. Diagnosis is based on clinical features because there is currently no reliable laboratory diagnostic tests. OBJECTIVE: We describe six cases of DABS with severe craniofacial deformations, three with and three without classical constrictive limb deformation. RESULTS: The craniofacial deformities were delimited by peripheral sharply demarcated scarring. CONCLUSION: When a sharply demarcated linear disruptive craniofacial lesion is observed, DABS should be considered despite the absence of constrictive limb scarring.

A 9p13-->p24 duplication coupled with a whole 22q translocation onto 9p24.

We report on a 3-year-old girl with a typical 9p trisomy syndrome, whose 45-chromosome karyotype includes a 9p+. As assessed by G, C and Ag-NOR bands, the rearranged chromosome resulted from a 9p13-->p24 direct duplication coupled with a translocation of the whole 22q onto 9pter, had heterochromatin at the junction site, lacked both nucleolar organizing regions (NORs) and centromere dots at the unconstricted fusion point, and was present in all metaphases scored. FISH results: a 9p subtelomere probe gave a diminished signal on the 9p+ precisely at the duplication junction 9p24::9p13, but no labeling was observed at the 9;22 translocation site; a pancentromeric alphoid probe labeled all centromeres, and gave a distinct signal at the 9pter;22cen junction. Hence, her karyotype was 45,XX,rea(9;22)(9qter-->9p24::9p13-->9p24::22p10-->22qter).ish rea(9;22) (9psubtel+dim,pancen+). Parental chromosomes were normal. The distinctiveness of the present centromere-telomere fusion rests on the coupling of an intrachromosomal distal duplication with a whole-arm translocation including alphoid DNA onto the duplicated segment. The centromeric inertia of the residual alphoid DNA in the present case compares with the variable functional status of the chromosome 22 centromere in true heterodicentrics involving such a chromosome.