Variants in the KIF1A gene can cause autosomal recessive spastic paraplegia 30, autosomal recessive hereditary sensory neuropathy, or autosomal (de novo) dominant mental retardation type 9. More... Show moreVariants in the KIF1A gene can cause autosomal recessive spastic paraplegia 30, autosomal recessive hereditary sensory neuropathy, or autosomal (de novo) dominant mental retardation type 9. More recently, variants in KIF1A have also been described in a few cases with autosomal dominant spastic paraplegia. Here, we describe 20 KIF1A variants in 24 patients from a clinical exome sequencing cohort of 347 individuals with a mostly 'pure' spastic paraplegia. In these patients, spastic paraplegia was slowly progressive and mostly pure, but with a highly variable disease onset (0-57 years). Segregation analyses showed a de novo occurrence in seven cases, and a dominant inheritance pattern in 11 families. The motor domain of KIF1A is a hotspot for disease causing variants in autosomal dominant spastic paraplegia, similar to mental retardation type 9 and recessive spastic paraplegia type 30. However, unlike these allelic disorders, dominant spastic paraplegia was also caused by loss-of-function variants outside this domain in six families. Finally, three missense variants were outside the motor domain and need further characterization. In conclusion, KIF1A variants are a frequent cause of autosomal dominant spastic paraplegia in our cohort (6-7%). The identification of KIF1A loss-of-function variants suggests haploinsufficiency as a possible mechanism in autosomal dominant spastic paraplegia. Show less
Hoorntje, E.T.; Spaendonck-Zwarts, K.Y. van; Rijdt, W.P.T.; L. boven; Vink, A.; Smagt, J.J. van der; ... ; Tintelen, J.P. van 2018
Aims We investigated the presence of a clinical diagnosis of hypertrophic cardiomyopathy (HCM) and of risk factors for sudden cardiac death (SCD) at the first cardiological evaluation after... Show moreAims We investigated the presence of a clinical diagnosis of hypertrophic cardiomyopathy (HCM) and of risk factors for sudden cardiac death (SCD) at the first cardiological evaluation after predictive genetic testing in asymptomatic carriers of an MYBPC3 gene mutation. Methods and results Two hundred and thirty-five mutation carriers were cardiologically evaluated on the presence of HCM and risk factors. A clinical diagnosis of HCM was made in 53 carriers (22.6%). Disease penetrance at 65 years was incomplete for all types of MYBPC3 gene mutations. Women were affected less often than men (15 and 32% respectively, P = 0.003) and disease penetrance was lower in females than in males (13 and 30% at 50 years, respectively, P = 0.024). One risk factor was present in 87 carriers and 9 had two or more risk factors. Twenty-five carriers (11%) with one or more risk factors and manifest HCM could be at risk for SCD. Conclusion At first cardiological evaluation almost one-quarter of asymptomatic carriers was diagnosed with HCM. Risk factors for SCD were frequently present and 11% of carriers could be at risk for SCD. Predictive genetic testing in HCM families and frequent cardiological evaluation on the presence of HCM and risk factors for SCD are justified until advanced age. Show less
