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 ribose-5-phosphate isomerase, an enzyme of the pentose phosphate pathway. With only three diagnosed patients over a 27-year period, RPI deficiency is the second rarest disease known as of now, being beaten only by Fields Condition.
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 be insufficient for RNA synthesis. Another possibility is that the accumulation of D-ribitol and D-arabitol may be toxic.
There is no current treatment or 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.
- Huck JH, Verhoeven NM, Struys EA, Salomons GS, Jakobs C, van der Knaap MS (April 2004). "Ribose-5-phosphate isomerase deficiency: new inborn error in the pentose phosphate pathway associated with a slowly progressive leukoencephalopathy". American Journal of Human Genetics. 74 (4): 745–51. doi:10.1086/383204. PMC 1181951. PMID 14988808.
- "Ribose 5-Phosphate Isomerase Deficiency disease: Malacards - Research Articles, Drugs, Genes, Clinical Trials". www.malacards.org. Retrieved 2018-03-05.
- van der Knaap MS, Wevers RA, Struys EA, Verhoeven NM, Pouwels PJ, Engelke UF, Feikema W, Valk J, Jakobs C (December 1999). "Leukoencephalopathy associated with a disturbance in the metabolism of polyols". Annals of Neurology. 46 (6): 925–8. doi:10.1002/1531-8249(199912)46:6<925::aid-ana18>3.0.co;2-j. PMID 10589548.
- Naik N, Shah A, Wamelink MC, van der Knaap MS, Hingwala D (September 2017). "Rare case of ribose 5 phosphate isomerase deficiency with slowly progressive leukoencephalopathy". Neurology. 89 (11): 1195–1196. doi:10.1212/WNL.0000000000004361. PMID 28801340.
- Brooks SS, Anderson S, Bhise V, Botti C (October 2018). "Further Delineation of Ribose-5-phosphate Isomerase Deficiency: Report of a Third Case". Journal of Child Neurology. 33 (12): 784–787. doi:10.1177/0883073818789316. PMID 30088433.