Genomic coordinate (human 13:40,789,611 SLC25A15).
Cytoband (human 13q14.11 SLC25A15).
OMIM’ genes @ 13q14.11 = 12 genes.
ClinVar = 454 SLC25A15 variants reported.
PANTHER Classification of SLC25A15 is PTHR45624 “Transporter” PC00227.
Here I 🎁 present: “HHH (Hyperornithinemia-Hyperammonemia-Homocitrullinuria) Syndrome”, Victor McKusick, Mendelian Inheritance in Man, 1966. (ORNT1)
INTRODUCTION.
ORNT1 (Mitochondrial Ornithine Transporter 1), also known as solute carrier family 25 member 15 (SLC25A15), is a vital transport protein localized to the inner mitochondrial membrane. It plays a critical role in the human body’s urea cycle, which metabolizes and removes toxic ammonia generated from the breakdown of proteins.
Biological Function
The primary job of ORNT1 is to facilitate an electroneutral antiport exchange. It transports cytosolic ornithine into the mitochondrial matrix in exchange for mitochondrial citrulline exporting out to the cytosol. This shuttle system directly connects the cytosolic and intramitochondrial steps of the urea cycle.
Beyond ornithine and citrulline, ORNT1 can also transport other basic amino acids across the membrane, including lysine and arginine.
Associated Medical Condition
When genetic mutations occur in the SLC25A15 gene, it results in an ORNT1 deficiency. This defect breaks the urea cycle chain, leaving the body unable to process waste nitrogen. The resulting autosomal recessive metabolic disorder is known as HHH Syndrome (Hyperornithinemia-Hyperammonemia-Homocitrullinuria syndrome).
Without functional ORNT1, toxic metabolites accumulate in the body and lead to Ornithine Translocase Deficiency symptoms, including:
- Hyperammonemia: A dangerous buildup of ammonia in the blood that can cause lethargy, confusion, and neurological damage.
- Neurological Impairment: Manifesting as cerebellar ataxia, cognitive delays, and motor function disturbances.
- Protein Intolerance & Hepatic Issues: Liver dysfunction or failure triggered by protein consumption.
