Study of color vision in fragile X syndrome

Abstract

Various theories have been postulated to account for the unusual inheritance pattern observed in the fragile X syndrome. The recent finding of a secondary amplification of the fragile X mutation in the offspring of carrier females [Oberle et al., 1991; Yu et al., 1991] is consistent with a maternal imprinting process. Laird [1987] has proposed that the fragile X mutation blocks complete reactivation of a previously inactivated fragile X chromosome. We have tested whether or not such a localized block extends as far distal as the red/green color-vision complex at Xq28. We found no evidence of color-vision defects among 25 male subjects with the fragile X syndrome. A fragile X positive woman also had normal color vision, despite being an obligate carrier of her father's gene for red/green color blindness. We conclude that the fragile X gene does not affect the function of neighboring color-vision genes, nor does it affect their ability to compensate adequately for inherited color deficiency on the homologous X chromosome in females.

Kit Ligand and Kit receptor tyrosine kinase sustain synaptic inhibition of Purkinje cells

“…Across several decades and species, it has been reported that KL and Kit are mutually expressed in discrete neuron populations known to be connected; it has thus been hypothesized that the expression pattern of KL-Kit may reflect a role in connectivity ( Keshet et al, 1991 ; Motro et al, 1991 ; Hirota et al, 1992 ; Manova et al, 1992 ). Consistent with such a function, case reports have implicated inactivating Kit mutations with disorders of the central nervous system ( Telfer et al, 1971 ; Finucane et al, 1991 ; Funderburk and Crandall, 1974 ; Lacassie et al, 1977 ; Kilsby et al, 2013 ; Figure 1—figure supplement 1C ). Clinical phenotypes include developmental delay, ataxia, hypotonia, intellectual disability, deafness, and autism spectrum disorder.…”

Kit Ligand and Kit receptor tyrosine kinase sustain synaptic inhibition of Purkinje Cells

“…Across several decades and species, it has been reported that KL and Kit are mutually expressed in discrete neuron populations known to be connected; it has thus been hypothesized that the expression pattern of KL-Kit may reflect a role in connectivity [5][6][7][8]. Consistent with such a function, case reports have implicated inactivating Kit mutations with disorders of the central nervous system (References [9][10][11][12][13] and Figure S1C). Clinical phenotypes include developmental delay, ataxia, hypotonia, intellectual disability, deafness, and autism spectrum disorder.…”