Lines between diseases blur

Importance of mutation databases heightened


As more becomes known about the genetic causes of neurological diseases, the lines between various diseases begin to blur because of the diversity and overlap between genetic mutations that cause them, and the diversity and overlap between the resulting symptoms.


This highlights the need to establish high quality databases of mutations to help with diagnosis, interpretation of gene tests, appropriate genetic counseling, and importantly, research into potential cures.


Hereditary spastic paraplegias (HSPs) constitute a heterogeneous group of neurological disorders, characterized primarily by progressive spasticity and weakness of the lower limbs. HSPs are caused by mutations in multiple genes (at least 48 loci and 28 causative genes). The clinical spectrum of HSPs is wide and important differences have been reported between patients with distinct mutations in the same gene, or even between different family members bearing the same mutation.


Many patients with HSP present clinical deficits related to the involvement of neuronal systems other than corticospinal tracts, namely, peripheral nerves, sensory, or cerebellar pathways. These cases may be difficult to differentiate from other neurological diseases (e.g. hereditary ataxias), also genetically and clinically heterogeneous. As an illustration of how overlapping this genotype-phenotype relationship is, and the difficulties that it brings upon the development of neurogenetic algorithms and databases, we review the main clinical and genetic features of HSPs, and summarize reports on cases of triplet-repeat spinocerebellar ataxias that can mimic HSP phenotypes.


This complex scenario makes the necessity of high-quality, curated mutation databases even more urgent, in order to develop adequate diagnostic guidelines, correct interpretation of genetic testing, and appropriate genetic counseling.


SOURCE:  Hum Mutat. 2012 Sep;33(9):1315-23. doi: 10.1002/humu.22148.

Revisiting genotype-phenotype overlap in neurogenetics: triplet-repeat expansions mimicking spastic paraplegias.

Bettencourt C, Quintáns B, Ros R, Ampuero I, Yáñez Z, Pascual SI, de Yébenes JG, Sobrido MJ.


Laboratorio de Biología Molecular, Instituto de Enfermedades Neurológicas, Fundación Socio-Sanitaria de Castilla la Mancha, Guadalajara, Spain. [email protected]


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