A deletion in the Hermansky–Pudlak syndrome 4 (Hps4) gene appears to be responsible for albinism in channel catfish

Abstract

Albinism is caused by a series of genetic abnormalities leading to reduction of melanin production. Albinism is quite frequent in catfish, but the causative gene and the molecular basis were unknown. In this study, we conducted a genome-wide association study (GWAS) using the 250 K SNP array. The GWAS analysis allowed mapping of the albino phenotype in the Hermansky-Pudlak syndrome 4 (Hps4) gene, which is known to be involved in melanosome biosynthesis. Sequencing analysis revealed that a 99-bp deletion was present in all analyzed albino catfish at the intron 2 and exon 3 junction. This deletion led to the skipping of the entire exon 3 which was confirmed by RT-PCR. Therefore, Hps4 was determined to be the candidate gene of the catfish albinism.

Effects of CRISPR/Cas9 dosage on TICAM1 and RBL gene mutation rate, embryonic development, hatchability and fry survival in channel catfish

“…Yolk and egg shells were removed from the embryos before DNA was extracted. DNA extraction was performed using proteinase K digestion and ethanol precipitation 62 . PCR and Surveyor® mutation detection assay were performed to identify the mutant embryos and fingerlings.…”

Periodic albinism of a widely used albino mutant of Xenopus laevis caused by deletion of two exons in the Hermansky–Pudlak syndrome type 4 gene

“…These findings indicate that the hps4 gene is responsible for the periodic albino mutation of X. laevis . Recently, hps4 was suggested to be a causative gene in albino catfish (Li et al., 2017). In addition, mutations of hps5 and hps6 have been reported to affect pigmentation in zebrafish (Daly et al., 2013) and Xenopus tropicalis (Nakayama et al., 2017).…”

“…These findings indicate that the hps4 gene is responsible for the periodic albino mutation of X. laevis. Recently, hps4 was suggested to be a causative gene in albino catfish (Li et al, 2017). In addition, mutations of hps5 and…”

Neonatal Oculocutaneous Albinism Type 2 With Prader-Willi Syndrome

“…The OCA2 gene is located on chromosome 15 and encodes for transporter protein P on the melanosome membrane. The P protein is an 838-aminoacid long polypeptide chain foldeand modi ed, and its three-dimensional structure contains 12 transmembrane helixes [14]. These transmembrane helices together form transport support, which transports tyrosine across the membrane to melanocytes and provides a substrate for melanin catalysis by tyrosinase in the melanin body [15].…”

“…Besides, patients with a heterozygous deletion mutation of OCA2 experience a minimal or reduced synthesis of the transporter. OCA2 carries a semisynthetic missense mutation c.2056G>A (guanine>adenine) on the remaining allele [16].This mutation substitutes alanine with threonine at 686 th position of the 9 th transmembrane helix, which results in the extension of the amino acid R group carbon chain [14]. This change signi cantly affects the spatial structure of the transporters, reduce or even prevent the transmembrane transport of tyrosine, and in uence the synthesis of melanin.…”