Creatine and guanidinoacetate reference values in a French population

Creatine and guanidinoacetate are biomarkers of creatine metabolism. Their assays in body fluids may be used for detecting patients with primary creatine deficiency disorders (PCDD), a class of inherited diseases. Their laboratory values in blood and urine may vary with age, requiring that reference normal values are given within the age range. Despite the long known role of creatine for muscle physiology, muscle signs are not necessarily the major complaint expressed by PCDD patients. These disorders drastically affect brain function inducing, in patients, intellectual disability, autistic behavior and other neurological signs (delays in speech and language, epilepsy, ataxia, dystonia and choreoathetosis), being a common feature the drop in brain creatine content. For this reason, screening of PCDD patients has been repeatedly carried out in populations with neurological signs. This report is aimed at providing reference laboratory values and related age ranges found for a large scale population of patients with neurological signs (more than 6 thousand patients) previously serving as a background population for screening French patients with PCDD. These reference laboratory values and age ranges compare rather favorably with literature values for healthy populations. Some differences are also observed, and female participants are discriminated from male participants as regards to urine but not blood values including creatine on creatinine ratio and guanidinoacetate on creatinine ratio values. Such gender differences were previously observed in healthy populations; they might be explained by literature differential effects of testosterone and estrogen in adolescents and adults, and by estrogen effects in prepubertal age on SLC6A8 function. Finally, though they were acquired on a population with neurological signs, the present data might reasonably serve as reference laboratory values in any future medical study exploring abnormalities of creatine metabolism and transport

A Solve-RD ClinVar-based reanalysis of 1522 index cases from ERN-ITHACA reveals common pitfalls and misinterpretations in exome sequencing

Purpose Within the Solve-RD project (https://solve-rd.eu/), the European Reference Network for Intellectual disability, TeleHealth, Autism and Congenital Anomalies aimed to investigate whether a reanalysis of exomes from unsolved cases based on ClinVar annotations could establish additional diagnoses. We present the results of the “ClinVar low-hanging fruit” reanalysis, reasons for the failure of previous analyses, and lessons learned. Methods Data from the first 3576 exomes (1522 probands and 2054 relatives) collected from European Reference Network for Intellectual disability, TeleHealth, Autism and Congenital Anomalies was reanalyzed by the Solve-RD consortium by evaluating for the presence of single-nucleotide variant, and small insertions and deletions already reported as (likely) pathogenic in ClinVar. Variants were filtered according to frequency, genotype, and mode of inheritance and reinterpreted. Results We identified causal variants in 59 cases (3.9%), 50 of them also raised by other approaches and 9 leading to new diagnoses, highlighting interpretation challenges: variants in genes not known to be involved in human disease at the time of the first analysis, misleading genotypes, or variants undetected by local pipelines (variants in off-target regions, low quality filters, low allelic balance, or high frequency). Conclusion The “ClinVar low-hanging fruit” analysis represents an effective, fast, and easy approach to recover causal variants from exome sequencing data, herewith contributing to the reduction of the diagnostic deadlock

Trisomie 22 en mosaïque (difficulté du diagnostic anténatal)

LILLE2-BU Santé-Recherche (593502101) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Methodology and geneticist's responsibility facing sociological aspects and specificities of a multiethnic society: The case of Reunion Island (Indian Ocean)

International audienceReunion Island, a French 'département' located in the Indian Ocean, is a multiethnic and multicultural society. Through a process of creolisation, it was shaped by biological and cultural contributions from Africa, Madagascar, Europe, and Asia (mainly India and China).The events involved in its settlement are highly documented by historical, archival, and genealogical sources and studies. Thus, concerning population genetics, this population appears to be a favourable field in order to study the formation processes of a population stemming from numerous admixtures. Nevertheless, through the example of Reunion, we show in this paper how it is important to take into consideration the ethno-social context of a multiethnic society, when one wants to study its shaping processes. The anthropologist has to take into account numerous sociological elements, such as folk knowledge and representations about DNA or race, and the socioeconomic context of the society formation. Indeed, the anthropologist has to reduce the potential gap between folk culture and scientific knowledge to be able to explain his aims and the methods he uses. In this way, the anthropologist will minimise the negative impact his work might have on the studied population. Lastly, in order to make the methodology more suited to the local specificities, we also show how the molecular anthropologist has to consider the cognitive anthropological and sociological studies dealing with the inquired population

À propos de six observations de double discordance cardiaque : faisabilité du diagnostic anténatal ?

International audienceThe double discrepancy (DD) is an exceptional cardiopathy, manifested by atrioventricular and ventriculo-arterial discordances. DD is rarely diagnosed in the antenatal period and is often found in adults when cardiac complications occur. We describe six cases of DD, the different forms, their ultrasound semiology, and the assessment of prognosis, correlated with the existence of associated cardiac anomalies.La double discordance (DD) est une cardiopathie exceptionnelle, se manifestant par une discordance auriculoventriculaire et ventriculoartérielle. La DD est rarement diagnostiquée en période anténatale et est souvent découverte chez l’adulte lorsque surviennent les complications cardiaques. Nous décrivons six observations de DD, les différentes formes et leur sémiologie échographique ainsi que l’évaluation du pronostic, corrélé à l’existence des anomalies cardiaques associées

Genetic data analysis of 10 Y-STR loci in two ethnic groups of Asian ancestry (Gujarat and Guangdong-Fujian provinces) from Reunion Island (Indian Ocean).

International audienceOne hundred and twenty-three unrelated individuals belonging to two ethnic groups (Shinwa and Zarab) of Asian ancestry from Reunion Island (Indian Ocean) were analyzed for 10 Y-STR loci. Haplotype diversity and frequencies were determined for loci DYS19, DYS385a/b, DYS388, DYS389I, DYS389II, DYS390, DYS391, DYS392, DYS393 and YCAIIa/b. The two ethnic groups do not share haplotypes, and a total of 98 distinct haplotypes were identified. Unique haplotypes were obtained for 49 Shinwa and 33 Zarab. Moreover, 52 of the identified distinct haplotypes revealed to have not been described to date

Complete Mitochondrial Sequences for Haplogroups M23 and M46: Insights into the Asian Ancestry of the Malagasy Population

Through the sequencing of the complete mitochondrial genome of three individuals of Malagasy ancestry, we completed the characterization of the island southeastern Asian specific M46 haplogroup. We assumed that the association of the np 3588 and np 16278 polymorphisms were M46 specific. In addition, we characterized a novel basal M subhaplogroup: M23. This clade can be defined by one coding region transition at np 10295 and one control region transition at np 16263. Our data suggest the arrival of South Asian migrants before the start of the 15th century and highlights the fact that future studies dealing with the settlement of Madagascar should consider at least three potential source populations (Africa, Indonesia, and India)

Evolution of the proto-MHC ancestral region: More evidence for the plesiomorphic organisation of human chromosome 9q34 region

International audienceThe present day structure of the vertebrate major histocompatibility complex (MHC) and its three paralogous regions has always been a focus of interest. In a recent study, nine human anchor genes located in the MHC region were cloned from a Branchiostoma floridae (amphioxus) cosmid library. The identification and analysis of 31 surrounding genes led to the most probable model of two rounds of en bloc duplication giving rise to these regions. These events were estimated to have occurred after the cephalochordata-craniata divergence [approximately 766 million years ago (Mya)] and before the Gnathostomata radiation (approximately 528 Mya). Furthermore, it was also shown that after this large-scale duplication one of these regions, corresponding to the human 9q33-q34, had retained an ancestral organisation. In the present study, four new cosmids in the amphioxus proto-MHC region were identified by the chromosomal walking technique. These cosmids were sequenced, and their structural annotation was performed, leading to the prediction of eleven genes. Their phylogenetic relationships among species corroborate the results obtained previously and provide more evidence for the plesiomorphic state of the human chromosome 9q33-34 MHC paralogous region

Antenatal presentation of hereditary lymphedema type I.

Fetal edema can present as limited subcutaneous edema, fluid accumulation in body cavities or hydrops fetalis. Hydrops fetalis is the end stage of a variety of fetal/maternal disorders and nonimmune etiology represents more than 3/4 of cases. Lymphatic dysplasia may account for a subset of patients with nonimmune and "idiopathic" hydrops fetalis, fetal chylous ascites or chylothorax. We present two unrelated patients with antenatal features of hereditary lymphedema syndrome, in whom Milroy disease was diagnosed after birth. At least, 20 genes have been identified to cause primary lymphedema, with sometimes antenatal features. Hereditary lymphedema syndrome should be considered in cases of nonimmune hydrops fetalis/fetal edema after ruling out the more common etiologies

Genetic variations creating microRNA target sites in the FXN 3'-UTR affect frataxin expression in Friedreich ataxia.

Friedreich's ataxia (FRDA) is a severe neurodegenerative disease caused by GAA repeat expansion within the first intron of the frataxin gene. It has been suggested that the repeat is responsible for the disease severity due to impaired transcription thereby reducing expression of the protein. However, genotype-phenotype correlation is imperfect, and the influence of other gene regions of the frataxin gene is unknown. We hypothesized that FRDA patients may harbor specific regulatory variants in the 3'-UTR. We sequenced the 3'-UTR region of the frataxin gene in a cohort of 57 FRDA individuals and 58 controls. Seven single nucleotide polymorphisms (SNPs) out of 19 were polymorphic in our case-control sample. These SNPs defined several haplotypes with one reaching 89% of homozygosity in patients versus 24% in controls. In another cohort of 47 FRDA Reunionese patients, 94% patients were found to be homozygous for this haplotype. We found that this FRDA 3'-UTR conferred a 1.2-fold decrease in the expression of a reporter gene versus the alternative haplotype configuration. We established that differential targeting by miRNA could account for this functional variability. We specifically demonstrated the involvement of miR-124 (i.e hsa-mir-124-3p) in the down-regulation of FRDA-3'-UTR. Our results suggest for the first time that post-transcriptional regulation of frataxin occurs through the 3'-UTR and involves miRNA targeting. We propose that the involvement of miRNAs in a FRDA-specific regulation of frataxin may provide a rationale to increase residual levels of frataxin through miRNA-inhibitory molecules