Abca13, an ATP-binding cassette subfamily A member, is predicted to be the largest ABC protein, consisting of 5058 amino acids with a long N-terminal region. It is involved in cholesterol trafficking, specifically accelerating cholesterol internalization by endocytic retrograde transport in neurons [1].

In Abca13 KO mice, deficits of prepulse inhibition were observed. Also, vesicular cholesterol accumulation and synaptic vesicle endocytosis were impaired in primary cultures of Abca13 KO cortical neurons, suggesting its importance in these neuronal functions [1]. Mutations in the ABCA13 gene have been associated with an increased susceptibility to psychiatric disorders such as schizophrenia, bipolar disorder, major depression, and autism spectrum disorder. These mutations can disrupt the protein's subcellular localization and impair cholesterol trafficking [1,2,4,6,7].

In addition, ABCA13 mRNA expression was significantly related to shorter overall survival in metastatic ovarian serous carcinoma, indicating its potential as a marker of poor outcome [3]. Moreover, an ABCA13-based ELISA showed good discriminatory power for detecting focal pathological forms of subclinical bovine paratuberculosis [5].

In conclusion, Abca13 is crucial for cholesterol trafficking in neurons. The study of Abca13 KO mouse models has revealed its significance in the pathophysiology of psychiatric disorders. Additionally, it shows potential as a biomarker in metastatic ovarian serous carcinoma and for detecting subclinical bovine paratuberculosis.