Ribose-5-phosphate isomerase deficiency
|Ribose-5-phosphate isomerase deficiency|
|Other names||RPI deficiency|
Ribose-5-phosphate isomerase deficiency is a human disorder caused by mutations in the pentose phosphate pathway enzyme ribose-5-phosphate isomerase. With only three diagnosed patients over a 27-year period, RPI deficiency is currently the rarest disease in the world.
In the search for an explanation for this rarity, it has been found that the patient has a seldom-seen allelic combination. One allele is a non-functional null allele, while the other encodes for a partially active enzyme. Furthermore, the partially functional allele has expression deficits that depend on the cell type in which it is expressed. Therefore, some of the patient's cells have a considerable amount of Rpi activity, whereas others do not.
The molecular cause of the pathology is not fully understood. One hypothesis is that ribose-5-phosphate may lack for RNA synthesis; another possibility is that the accumulation of D-ribitol and D-arabitol may be toxic.
There is no current treatment as well as prognosis for ribose-5-phosphate isomerase deficiency.
In 1999 van der Knaap and colleagues   described a 14-year-old boy with developmental delay, insidious psychomotor regression, epilepsy, leukoencephalopathy and abnormal polyol metabolism. Later, Naik and colleagues  reported a second case, an 18-year-old man with seizures, psychomotor regression and diffuse white matter abnormality. A third case was reported in 2018 by Sklower Brooks and colleagues, a child with neonatal onset leukoencephalopathy and psychomotor delays.
- "OMIM Entry - # 608611 - RIBOSE 5-PHOSPHATE ISOMERASE DEFICIENCY". omim.org. Retrieved 16 March 2019.
- "Ribose 5-Phosphate Isomerase Deficiency disease: Malacards - Research Articles, Drugs, Genes, Clinical Trials". www.malacards.org. Retrieved 2018-03-05.
- van der Knapp MS, Wevers RA, Struys EA, et al. Leukoencephalopathy associated with a disturbance in the metabolism of polyols.Ann Neurol. 1999;46(6):925-928.
- Huck, J. H. J.; Verhoeven, N. M.; Struys, E. A.; Salomons, G. S.; Jakobs, C.; Van Der Knaap, M. S. (2004). "Ribose-5-Phosphate Isomerase Deficiency: New Inborn Error in the Pentose Phosphate Pathway Associated with a Slowly Progressive Leukoencephalopathy". The American Journal of Human Genetics 74 (4): 745–751. PMC 1181951. PMID 14988808. doi:10.1086/383204.
- Naik N, Shah A, Wamelink MMC, van der Knaap MS, Hingwala D. Rare case of ribose 5 phosphate isomerase deficiency with slowly progressive leukoencephalopathy. Neurology. 2017;89:1-2.
- Sklower Brooks S, Anderson S, Bhise V, Botti C. Further Delineation of Ribose-5-phosphate Isomerase Deficiency: Report of a Third Case, Journal of Child Neurology: First Published August 10, 2018 Journal of Child Neurology. https://doi.org/10.1177/0883073818789316