Skeletal dysplasias are group of rare genetic diseases resulting from mutations in genes encoding structural proteins of the cartilage extracellular matrix (ECM), signaling molecules, transcription factors, epigenetic modifiers, and several intracellular proteins. Cell division, organelle maintenance, and intracellular transport are all orchestrated by the cytoskeleton-associated proteins, and intracellular processes affected through microtubule-associated movement are important for the function of skeletal cells. Among microtubule-associated motor proteins, kinesins in particular have been shown to play a key role in cell cycle dynamics, including chromosome segregation, mitotic spindle formation, and ciliogenesis, in addition to cargo trafficking, receptor recycling, and endocytosis. Recent studies highlight the fundamental role of kinesins in embryonic development and morphogenesis and have shown that mutations in kinesin genes lead to several skeletal dysplasias. However, many questions concerning the specific functions of kinesins and their adaptor molecules as well as specific molecular mechanisms in which the kinesin proteins are involved during skeletal development remain unanswered. Here we present a review of the skeletal dysplasias resulting from defects in kinesins and discuss the involvement of kinesin proteins in the molecular mechanisms that are active during skeletal development.

BACKGROUND: Hereditary spastic paraplegias (HSPs) are a group of genetically heterogeneous neurodegenerative disorders. Our objective was to determine the clinical and molecular characteristics of patients with genetically confirmed childhood-onset HSPs and to expand the genetic spectrum for some rare subtypes of HSP.
METHODS: We reviewed the charts of subjects with genetically confirmed childhood-onset HSP. The age at the disease onset was defined as the point at which the delayed motor milestones were observed. Delayed motor milestones were defined as being unable to hold the head up by four months, sitting unassisted by nine months, and walking independently by 17 months. If there were no delayed motor milestones, age at disease onset was determined by leg stiffness, frequent falls, or unsteady gait. Genetic testing was performed based on delayed motor milestones, progressive leg spasticity, and gait difficulty. The variant classification was determined based on the American College of Medical Genetics standard guidelines for variant interpretation. Variants of uncertain significance (VUS) were considered disease-associated when clinical findings were consistent with the previously described disease phenotypes for pathogenic variants. In addition, in the absence of another pathogenic, likely pathogenic, or VUS variant that could explain the phenotype of our cases, we concluded that the disease is associated with VUS in the HSP-causing gene. Segregation analysis was also performed on the parents of some patients to demonstrate the inheritance model.
RESULTS: There were a total of 18 patients from 17 families. The median age of symptom onset was 18 months (2 to 84 months). The mean delay between symptom onset and genetic diagnosis was 5.8 years (5 months to 17 years). All patients had gait difficulty caused by progressive leg spasticity and weakness. Independent walking was not achieved at 17 months for 67% of patients (n = 12). In our cohort, there were two subjects each with SPG11, SPG46, and SPG 50 followed by single subject each with SPG3A, SPG4, SPG7, SPG8, SPG30, SPG35, SPG43, SPG44, SPG57, SPG62, infantile-onset ascending spastic paralysis (IAHSP), and spastic paraplegia and psychomotor retardation with or without seizures (SPPRS). Eight novel variants in nine patients were described. Two affected siblings had a novel variant in the GBA2 gene (SPG46), and one subject each had a novel variant in WASHC5 (SPG8), SPG11 (SPG11), KIF1A (SPG30), GJC2 (SPG44), ERLIN1 (SPG62), ALS2 (IAHSP), and HACE1 (SPPRS). Among the novel variants, the variant in the SPG11 was pathogenic and the variants in the KIF1A, GJC2, and HACE1 were likely pathogenic. The variants in the GBA2, ALS2, ERLIN1, and WASHC5 were classified as VUS.
CONCLUSIONS: There was a significant delay between symptom onset and genetic diagnosis of HSP. An early diagnosis may be possible by examining patients with delayed motor milestones, progressive spasticity, gait difficulties, and neuromuscular weakness in the context of HSP. Eight novel variants in nine patients were described, clinically similar to the previously described disease phenotype associated with pathogenic variants. This study contributes to expanding the genetic spectrum of some rare subtypes of HSP.

Our understanding of genetic and phenotypic heterogeneity associated with the clinical spectrum of rare diseases continues to expand. Thorough phenotypic descriptions and model organism functional studies are valuable tools in dissecting the biology of the disease process. Kinesin genes are well known to be associated with specific disease phenotypes and a subset of kinesin genes, including KIF21A, have been associated with more than one disease. Here we report two patients with KIF21A variants identified by exome sequencing; one with biallelic variants, supporting a novel KIF21A related syndrome with recessive inheritance and the second report of this condition, and another with a heterozygous de novo variant allele representing a phenotypic expansion of the condition described to date. We provide detailed phenotypic information on both families, including a novel neuropathology finding of neuroaxonal dystrophy associated with biallelic variants in KIF21A. Additionally, we studied the dominant variant in Saccharomyces cerevisiae to assess variant pathogenicity and found that this variant appears to impair protein function. KIF21A associated disease has mounting evidence for phenotypic heterogeneity; further patients and study of an allelic series are required to define the phenotypic spectrum and further explore the molecular etiology for each of these conditions.

The objective of this study was to investigate the pathogenesis and inheritance pattern of a Chinese Han family with hereditary spastic paraplegia and to retrospectively analyze the characteristics of KIF1A gene variants and related clinical manifestations.
High-throughput whole-exome sequencing was performed on members of a Chinese Han family with a clinical diagnosis of hereditary spastic paraplegia, and the sequencing results were validated by Sanger sequencing. Deep high-throughput sequencing was performed on subjects with suspected mosaic variants. The previously reported pathogenic variant loci of the KIF1A gene with complete data were collected, and the clinical manifestations and characteristics of the pathogenic KIF1A gene variant were analyzed.
A pathogenic heterozygous variant located in the neck coil of the KIF1A gene (c.1139G>C, p.Arg380Pro) was identified in the proband and four additional members of the family. It was derived from the de novo low-frequency somatic-gonadal mosaicism of the proband\'s grandmother and had a rate of 10.95%.
This study helps us to better understand the pathogenic mode and characteristics of mosaic variants, and to understand the location and clinical characteristics of pathogenic variants in KIF1A.

OBJECTIVE: This retrospective non-randomised study aims to identify new and rare fusion partners with USP6 in the setting of nodular fasciitis. It has been proven, that nodular fasciitis can harbour different variants of USP6 fusions, which can be used in routine diagnostics and even determine the biological behaviour of the process.
METHODS: A total of 19 cases of nodular fasciitis examined between 2011 and 2022 at Motol University Hospital in Prague were included into this study. Next to the histopathological evaluation, all cases were assessed using immunohistochemistry, RT-PCR and Anchored multiplex RNA methods. Patient\'s main demographic characteristics and corresponding clinical data were also analysed.
RESULTS: This study presents one novel (KIF1A) and five rare examples (TMP4, SPARC, EIF5A, MIR22HG, COL1A2) of fusion partners with USP6 among 19 cases of nodular fasciitis.
CONCLUSIONS: Identification of USP6 fusion partners in nodular fasciitis helps to understand the biology of such lesions. Moreover, it can be useful in routine histopathological practice of soft-tissues diagnostics, especially in preventing possible misdiagnosis of malignancy.

暂无摘要。

Renal-hepatic-pancreatic dysplasia type 1 (RHPD1) is a rare sporadic and autosomal recessive disorder with unknown incidence. RHPD1 is caused by biallelic pathogenic variants in NPHP3, which encode nephrocystin, an important component of the ciliary protein complex.
In this case report, we describe a male newborn who was confirmed by ultrasound to have renal enlargement with multiple cysts, pancreatic enlargement with cysts, and increased liver echogenicity, leading to the clinical diagnosis of RHPD. In addition, a compound heterozygous pathogenic variant, namely, NPHP3 c.1761G > A (p. W587*) and the c.69delC (p. Gly24Ala24*11) variant, was detected by WES. The patient was clinically and genetically diagnosed with RHPD1. At 34 h of life, the infant died of respiratory insufficiency.
This is the first published case of RHPD1 in China. This study broadens the known range of RHPD1 due to NPHP3 pathogenic variants.

The maize abnormal chromosome 10 (Ab10) haplotype encodes a meiotic drive system that converts heterochromatic knobs into centromere-like bodies that are preferentially segregated through female meiosis. Ab10 was first described in the 1940s and has been intensively studied. Here I provide a comprehensive review of the literature, starting from the discovery of knobs and Ab10, preceding through the classic literature, and finishing with molecular structure and mechanisms. The defining features of the Ab10 haplotype are its two specialized kinesins, Kinesin driver and TR-1 kinesin, that activate neocentromeres at knobs containing different classes of the tandem repeat. In most Ab10 haplotypes, the two kinesin/knob systems cooperate to promote maximum meiotic drive. However, recent interpretations suggest that each kinesin/knob system can function as an independent meiotic driver and that in some cases they compete with each other. Ab10 is present at low frequencies throughout the genus Zea and has significantly expanded genome size by promoting the formation of knobs throughout the genome.

The clinical data for a patient with primary lung adenocarcinoma complicated with pulmonary hamartoma, who admitted to Zunyi Medical University Hospital in September 2020, was retrospectively analyzed. The 62-years-old male visited outpatient service because of dysphagia in March 2015, and the pulmonary nodules were found. In September 2020, the computed tomography indicated the enlarged nodule in the lower lobe of left lung with lobulation, and there was ground glass nodule in the upper lobe of left lung. After thoracoscopic wedge surgery, the primary pulmonary adenocarcinoma in the upper lobe of left lung and pulmonary hamartoma in the lower lobe of left lung were confirmed by pathology. Whole exon sequencing revealed that kinesin family member 20B (KIF20B) gene was not expressed in lung adenocarcinoma, but was expressed in pulmonary hamartoma. The clinical manifestations of lung adenocarcinoma complicated with pulmonary hamartoma was not typical, which could locate in the same side and different sides of the lung. The imaging manifestations of the 2 kinds of tumors were diverse and can not be completely distinguished. The pathological examination after surgery is the gold standard, and the possibility of malignant transformation of pulmonary hamartoma should be warned.
遵义医科大学附属医院于2020年9月收治的原发性肺腺癌合并肺错构瘤患者1例，男，62岁，以吞咽困难就诊。2015年3月发现肺结节于门诊规律随访，2020年9月胸部CT显示左肺下叶结节增大、有分叶，左肺上叶有磨玻璃结节影，行胸腔镜下楔形手术，术后病理确诊为左肺上叶原发性肺腺癌、左肺下叶肺错构瘤。全外显子组测序发现驱动蛋白20(kinesin family member 20B，KIF20B)基因在肺腺癌中无表达，在肺错构瘤中有表达。肺腺癌合并肺错构瘤的临床表现不典型，可位于同侧及对侧肺叶，两者影像学表现多样，不能完全区分，手术后的病理学检查是金标准，需警惕肺错构瘤恶变的可能。.

Hereditary spastic paraplegia (HSP) encompasses several rare genetic disorders characterized by progressive lower extremity spasticity and weakness caused by corticospinal tract degeneration. Published literature on genetically confirmed pediatric HSP cases is limited.
We conducted a retrospective review of childhood-onset HSP cases followed in the neuromuscular clinics at Children\'s and Emory Healthcare in Atlanta. Clinical presentation, family history, examination, electrodiagnostic data, neuroimaging, genetic test results, comorbidities, and treatment were recorded.
Sixteen patients with HSP (eight males, eight females) with a mean age 19 years ± 15.7 years were included. Ten patients (66%) presented with gait difficulty. Seven (44%) were ambulatory at the last clinic follow-up visit with an average disease duration of 7.4 years. Genetically confirmed etiologies included SPAST (3 patients), MARS (2), KIF1A (2), KIF5A (1), SACS (1), SPG7 (1), REEP1 (1), PNPT1 (1), MT-ATP6 (1), and ATL1 (1). Symptom onset to genetic confirmation on an average was 8.2 years. Sensory motor axonal polyneuropathy was found in seven patients, and two exhibited cerebellar atrophy on magnetic resonance imaging (MRI) of the brain. Neurological comorbidities included developmental delay (n = 9), autism (n = 5), epilepsy (n = 3), and attention-deficit/hyperactivity disorder (n = 2).
In our study, a significant proportion (70%) of subjects with childhood-onset HSP had comorbid neurocognitive deficits, polyneuropathy with or without neuroimaging abnormalities, and rare genetic etiology. Genetic diagnosis was established either through inherited genetic neuropathy panel or whole-exome sequencing, which supports the utility of whole-exome sequencing in aiding in HSP diagnosis.