Inspired by colleagues’ patients
Wang J, Zhang Q, Chen Y, Yu S, Wu X, Bao X. Rett and Rett-like syndrome: Expanding the genetic spectrum to KIF1A and GRIN1 gene. Mol Genet Genomic Med. 2019 Nov;7(11):e968.
This study aimed to investigate the new genetic etiologies of Rett syndrome (RTT) or Rett-like phenotypes.
Targeted next-generation sequencing (NGS) was performed on 44 Chinese patients with RTT or Rett-like phenotypes, in whom genetic analysis of MECP2, CDKL5, and FOXG1 was negative.
The detection rate was 31.8% (14/44). A de novo pathogenic variant (c.275_276ins AA, p. Cys92*) of KIF1A was identified in a girl with all core features of typical RTT. A patient with atypical RTT was detected having de novo GRIN1 pathogenic variant (c.2337C > A, p. Val793Phe). Additionally, compound heterozygous pathogenic variants of PPT1 gene were detected in a girl, who initially displayed typical RTT features, but progressed into neuronal ceroid lipofuscinoses (NCL) afterwards. Pathogenic variants in KCNQ2, MEF2C, WDR45, TCF4, IQSEC2, and SDHA were also found in our cohort.
It is the first time that pathogenic variants of GRIN1 and KIF1A were linked to RTT and Rett-like profiles. Our findings expanded the genetic heterogeneity of Chinese RTT or Rett-like patients, and also suggest that some patients with genetic metabolic disease such as NCL, might displayed Rett features initially, and clinical follow-up is essential for the diagnosis.
Pennings M, Schouten MI, van Gaalen J, Meijer RPP, de Bot ST, Kriek M, Saris CGJ, van den Berg LH, van Es MA, Zuidgeest DMH, Elting MW, van de Kamp JM, van Spaendonck-Zwarts KY, Die-Smulders C, Brilstra EH, Verschuuren CC, de Vries BBA, Bruijn J, Sofou K, Duijkers FA, Jaeger B, Schieving JH, van de Warrenburg BP, Kamsteeg EJ. KIF1A variants are a frequent cause of autosomal dominant hereditary spastic paraplegia. Eur J Hum Genet. 2020 Jan;28(1):40-49.
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 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.
Van Beusichem AE, Nicolai J, Verhoeven J, Speth L, Coenen M, Willemsen MA, Kamsteeg EJ, Stumpel C, Vermeulen RJ. Mobility Characteristics of Children with Spastic Paraplegia Due to a Mutation in the KIF1A Gene. Neuropediatrics. 2019 Dec 5. doi: 10.1055/s-0039-3400988. [Epub ahead of print]
Several de novo variants in the KIF1A gene have been reported to cause a complicated form of hereditary spastic paraplegia. Additional symptoms include cognitive impairment and varying degrees of peripheral neuropathy, epilepsy, decreased visual acuity, and ataxia. We describe four patients (ages 10-18 years), focusing on their mobility and gait characteristics. Two patients were not able to walk without assistance and showed a severe abnormal gait pattern, crouch gait. At examination, severe contractures were found.In addition to describing the different phenotypes with specific attention to gait in our cases, we reviewed known KIF1A mutations and summarized their associated phenotypes.We conclude that mobility and cognition are severely affected in children with spastic paraplegia due to de novo KIF1A mutations. Deterioration in mobility is most likely due to progressive spasticity, muscle weakness, and the secondary development of severe contractures, possibly combined with an additional progressive polyneuropathy. Close follow-up and treatment of these patients are warranted.
Kurihara M, Ishiura H, Bannai T, Mitsui J, Yoshimura J, Morishita S, Hayashi T, Shimizu J, Toda T, Tsuji S. A Novel de novoKIF1A Mutation in a Patient with Autism, Hyperactivity, Epilepsy, Sensory Disturbance, And Spastic Paraplegia. Intern Med. 2019 Dec 6. doi: 10.2169/internalmedicine.3661-19. [Epub ahead of print]
Heterozygous mutations in KIF1A have been reported to cause syndromic intellectual disability or pure spastic paraplegia. However, their genotype-phenotype correlations have not been fully elucidated. We herein report a man with autism and hyperactivity along with sensory disturbance and spastic paraplegia, carrying a novel de novo mutation in KIF1A (c.37C>T [p.R13C]). Autism and hyperactivity have only previously been reported in a patient with c.38 G>A (R13H) mutation. This case suggests that alterations in this arginine at codon 13 might lead to a common clinical spectrum and further expand the genetic and clinical spectra associated with KIF1A mutations.
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