Dopachrome tautomerase variants in patients with oculocutaneous albinism.

Pennamen, P.; Tingaud-Sequeira, A.; Gazova, I.; Keighren, M.; McKie, L.; Marlin, S.; Gherbi Halem, S.; Kaplan, J.; Delevoye, C.; Lacombe, D.; Plaisant, C.; Michaud, V.; Lasseaux, E.; Javerzat, S.; Jackson, I.; Arveiler, B.

doi:10.1101/2020.06.26.171223

bioRxiv · 10.1101/2020.06.26.171223

Dopachrome tautomerase variants in patients with oculocutaneous albinism.

Pennamen, P.·Tingaud-Sequeira, A.·Gazova, I.·Keighren, M.·McKie, L.·Marlin, S.·Gherbi Halem, S.·Kaplan, J.·Delevoye, C.·Lacombe, D.·Plaisant, C.·Michaud, V.·Lasseaux, E.·Javerzat, S.·Jackson, I.·Arveiler, B.

View original source ↗Export metadata ↓

Abstract

PurposeAlbinism is a clinically and genetically heterogeneous condition. Despite analysis of the nineteen known genes, [~]30% patients remain unsolved. We aimed to identify new genes involved in albinism. MethodsWe sequenced a panel of genes with known or predicted involvement in melanogenesis in 230 unsolved albinism patients. ResultsWe identified variants in the Dopachrome tautomerase (DCT) gene in two patients. One was compound heterozygous for a 14 bp deletion in exon 9 and c.118T>A p.(Cys40Ser). The second was homozygous for c.183C>G p.(Cys61Trp). Both patients had mild hair and skin hypopigmentation, and classical ocular features. CRISPR/Cas9 was used in C57BL/6J mice to create mutations identical to the missense mutations carried by the patients, along with one loss-of-function indel mutation. When bred to homozygosity the three mutations revealed hypopigmentation of the coat, milder for Cys40Ser compared to Cys61Trp or the frameshift mutation. Histological analysis identified significant hypopigmentation of the retinal pigmented epithelium (RPE) indicating that defective RPE melanogenesis could be associated with eye and vision defects. DCT loss of function in zebrafish embryos elicited hypopigmentation both in melanocytes and RPE cells. ConclusionsDCT is the gene for a new type of oculocutaneous albinism that we propose to name OCA8.

Source connections

Published article ↗

Explore related subjects

genetics Preprint

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

Pennamen, P., Tingaud-Sequeira, A., Gazova, I., Keighren, M., McKie, L., Marlin, S., Gherbi Halem, S., Kaplan, J., Delevoye, C., Lacombe, D., Plaisant, C., Michaud, V., Lasseaux, E., Javerzat, S., Jackson, I., Arveiler, B.. 2020-06-27. Dopachrome tautomerase variants in patients with oculocutaneous albinism.. https://doi.org/10.1101/2020.06.26.171223

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

bioRxiv2026

The histone demethylase Kdm5 and the ARGONAUTE proteins Piwi and Aubergine regulate female abdominal pigmentation in Drosophila melanogaster

Insect pigmentation is an ecologically critical trait influencing many physiological processes. In Drosophila melanogaster, abdominal pigmentation is sexually dimorphic: males have fully pigmented posterior segments, while females exhibit a posterior melanin stripe. Pigmentation relies on the expression of pigmentation genes that encode enzymes involved in pigment synthesis. These genes are tightly regulated during pupal and young adult stages. To expand the gene regulatory network of pigmentation genes, we conducted an RNAi screen using the yellow-Gal4 driver, expressed during the pupal stage in abdominal epidermis. One of the candidates from this screen, Kdm5, encodes a histone demethylase erasing the H3K4me3 histone mark catalyzed by the histone methyl-transferase Trithorax (Trx). We show that Kdm5 down-regulation reduces abdominal pigmentation, mimicking trx down-regulation. Kdm5 activates melanin production through regulation of the pigmentation gene tan. Transcriptomic analyses reveal that Kdm5 and Trx share many targets in pupal abdominal epidermis, including piRNA pathway components such as piwi and aubergine. These piRNA components, originally associated with transposon silencing in the germline, also function in some somatic tissues such as the nervous system, the fat body or the gut. We demonstrate that Piwi and Aubergine participate in female abdominal pigmentation establishment, without evident piRNA production. We also show that Kdm5 and Piwi act not only in pupal abdominal epidermis but also in pupal fat body. This study therefore expands the regulatory network of pigmentation genes. It identifies a new somatic function for Kdm5 and Piwi and reveals a role for pupal fat body in female abdominal pigmentation regulation.

genetics↗

bioRxiv2026

Genetic diversity within and between polyploid sugarcane (Saccharum spp.) families obtained via caryopsis using microsatellite markers and multicategory model

Genetic diversity analyses are essential for sugarcane (Saccharum spp.) breeding programs. Crossbreeding, based on genetic distances between parental plants, is a tool used to increase genetic variability and enhance plant selection; however, quantifying variation in highly polyploid species remains a challenge. The present study aimed to evaluate the diversity within and between 12 families of sugarcane derived from caryopses, analyzing 120 individual seedlings arranged in an augmented block design. Genotyping was performed using primers for 16 microsatellite loci, five simple sequence repeat (SSR) loci, and 11 expressed sequence tag-SSR (EST-SSR) loci. To accurately account for polyploidy, similarity calculations were performed using Bruvos distances among individuals and RST distances among the families. Analysis of molecular variance (AMOVA) indicated that most of the genetic variability was within families (72%), with only 28% found between them. This high level of intra-family variation demonstrates that a significant reservoir of genetic diversity remains available within the crosses. The highest genetic similarity was observed between the families RB986952 x RB986960 and RB036122 x RB03611, whereas the lowest genetic similarity was observed between the families RB97319 x RB966928 and RB106802 x RB855036. Although the evaluated families shared high genetic similarity, the pronounced genetic variation within them demonstrates a robust recombination potential, indicating that the genetic basis of sugarcane can be better explored using the high variability that already exists in the selection of desirable morpho-agronomic characteristics within the families. Furthermore, this study highlights the importance of using appropriate distances for diversity studies with codominant markers, such as microsatellites, in polyploid species.

genetics↗

bioRxiv2026

Optimizing DNA extraction from environmentally degraded bone samples for molecular identification of cetacean species

Molecular identification of cetacean bone remains can be limited by DNA degradation and the presence of PCR inhibitors. Here, we present an optimized DNA extraction protocol based on a total demineralization method for environmentally exposed cetacean bones. The protocol uses 100 mg of bone powder, 24 h digestion with EDTA, N-lauroylsarcosine, and proteinase K, followed by a modified silica-column purification. Nine environmentally degraded bone samples representing eight individuals were processed. DNA concentrations ranged from 7.3 to 57.1 ng/uL (mean SD = 25.91- 13.91 ng/uL). The mitochondrial cytochrome b gene was successfully amplified from all samples using conventional PCR, and five samples (55.6%) yielded sequences suitable for downstream analysis. BLASTn identified Balaenoptera physalus as the closest database match for all recovered sequences, and phylogenetic analysis further supported their association with B. physalus reference sequences. These results demonstrate that the proposed protocol provides a practical approach for recovering amplifiable and molecularly informative mitochondrial DNA from environmentally degraded cetacean bone material, facilitating molecular identification from challenging skeletal remains.

genetics↗