BACKGROUND: The Triggering Receptor Expressed on Myeloid Cells 2 protein (TREM2) plays a crucial role in various biological processes, including osteoclast differentiation, and disease-associated microglia (DAM) activation to regulate neuroinflammation, and phagocytosis in the brain. Genetic variations in TREM2 are implicated in neurodegenerative disorders, such as Nasu-hakola disease (NHD), characterized by bone lesions, neuropsychiatric disorders, and early-onset dementia.
METHODS: We studied 3 siblings with suspected NHD. Whole-exome sequencing was conducted on the proband to identify the possible genetic cause(s) and by Sanger sequencing to validate the identified variants in the two other affected siblings, a healthy sister, and the parents.
RESULTS: We identified a novel homozygous deletion (c.549del; p.(Leu184Serfs*5)) in TREM2. Our literature review reveals 16 TREM2 mutations causing early-onset dementia and bone lesions.
CONCLUSIONS: These findings, alongside previous research, elucidate the clinical spectrum of TREM2-related diseases, aiding accurate diagnosis and patient care. This knowledge is vital for understanding TREM2-dependent DAM and its involvement in the pathogenesis of neurodevelopmental disorders which can help to develop targeted therapies and improve outcomes for TREM2-affected individuals.

BACKGROUND: Hypohidrotic ectodermal dysplasia (HED) is a genetic disorder that results in the abnormal development of structures derived from ectodermal tissue. This rare condition predominantly affects the hair, nails, eccrine glands, and teeth. While HED can be caused by various genes, the EDA, EDAR, EDARADD, and WNT10A genes account for approximately 90% of cases. Notably, HED forms associated with variants in the EDA, EDAR, or EDARADD genes may exhibit similar phenotypes due to defects in a common signaling pathway. Proper interaction among the products of these genes is crucial for the activation of the nuclear factor (NF-κB) signaling pathway, which subsequently regulates the transcription of targeted genes. The EDARADD gene, in particular, harbors one of the rarest reported variants associated with HED.
METHODS: Five-and two-years-old brothers born into consanguineous parents were examined at our outpatient medical genetics clinic at Sanliurfa Training and Research Hospital, Turkey. Both displayed the same classical phenotypic features of HED. The elder had a very sparse dark and brittle hair, sparse eyebrows and eyelashes, conical upper and lower premolar teeth with hypodontia, widely spaced teeth, very dry skin, mildly prominent forehead, and periorbital wrinkles. The younger one showed the same, but less severe, clinical features. After thorough examination and patient history evaluation, targeted next-generation sequencing analysis yielded the novel homozygous insertion variant c.322_323insCGGGC p.(Arg108ProfsTer7) in EDARADD. The mutation has not been reported to date in the literature.
CONCLUSIONS: In this report, we present two siblings exhibiting classical HED symptoms and a novel insertion variant of the EDARADD gene, which leads to a frameshift introducing a stop codon. Both brothers inherited such mutation from their parents, who were heterozygous carriers of the same variant. The present study may shed light about the pathogenic mechanisms underlying HED, and expand the spectrum of EDARADD gene variants associated with this condition.

BACKGROUND: Hypomyelinating leukodystrophy-9 (HLD-9) is caused by biallelic pathogenic variants in RARS1, which codes for the cytoplasmic tRNA synthetase for arginine (ArgRS). This study aims to evaluate the clinical, neuroradiological, and genetic characteristics of patients with RARS1-related disease and determine probable genotype-phenotype relationships.
METHODS: We identified three patients with RARS1 homozygous pathogenic variants. Furthermore, we performed a comprehensive review of the literature.
RESULTS: Homozygous variants of RARS1 (c.2T>C (p.Met1Thr)) were identified in three patients with HLD-9. Clinical symptoms were severe in all patients. Following the literature review, thirty HLD-9 cases from eight studies were found. The 33 patients\' main symptoms were hypomyelination, language delay, and intellectual disability or developmental delay. The mean age of onset for HLD9 in the group of 33 patients with a known age of onset was 5.8 months (SD = 8.1). The interquartile range of age of onset was 0-10 months. Of the 25 variants identified, c.5A>G (p.Asp2Gly) was identified in 11 patients.
CONCLUSIONS: Pathogenic variants in RARS1 decrease ArgRS activity and cause a wide range of symptoms, from severe, early onset epileptic encephalopathy with brain atrophy to a mild condition with relatively maintained myelination. These symptoms include the classic hypomyelination presentation with nystagmus and spasticity. Furthermore, the pathogenicity of the variation c.2T>C (p.Met1Thr) has been shown.

OBJECTIVE: To characterize the phenotype spectrum, diagnosis, and response to growth-promoting therapy in patients with ACAN variants causing familial short stature.
METHODS: Three families with ACAN variants causing short stature were reported. Similar cases in the literature were summarized, and the genotype and phenotype were analyzed.
RESULTS: Three novel heterozygous variants, c.757+1G>A, (splicing), c.6229delG, p.(Asp2078Tfs*1), and c.6679C>T, p.(Gln2227*) in the ACAN gene were identified. A total of 314 individuals with heterozygous variants from 105 families and 8 individuals with homozygous variants from 4 families were confirmed to have ACAN variants from literature and our 3 cases. Including our 3 cases, the variants reported comprised 33 frameshift, 39 missense, 23 nonsense, 5 splicing, 4 deletion, and 1 translocation variants. Variation points are scattered throughout the gene, while exons 12, 15, and 10 were most common (25/105, 11/105, and 10/105, respectively). Some identical variants existing in different families could be hot variants, c.532A>T, p.(Asn178Tyr), c.1411C>T, p.(Gln471*), c.1608C>A, p.(Tyr536*), c.2026+1G>A, (splicing), and c.7276G>T, p.(Glu2426*). Short stature, early-onset osteoarthritis, brachydactyly, midfacial hypoplasia, and early growth cessation were the common phenotypic features. The 48 children who received rhGH (and GnRHa) treatment had a significant height improvement compared with before (-2.18 ± 1.06 SD vs. -2.69 ± 0.95 SD, p < 0.001). The heights of children who received rhGH (and GnRHa) treatment were significantly improved compared with those of untreated adults (-2.20 ± 1.10 SD vs. -3.24 ± 1.14 SD, p < 0.001).
CONCLUSIONS: Our study achieves a new understanding of the phenotypic spectrum, diagnosis, and management of individuals with ACAN variants. No clear genotype-phenotype relationship of patients with ACAN variants was found. Gene sequencing is necessary to diagnose ACAN variants that cause short stature. In general, appropriate rhGH and/or GnRHa therapy can improve the adult height of affected pediatric patients caused by ACAN variants.

Biallelic pathogenic variants in ZNF335 are one of the genetic causes of microcephaly, reported only in the past decade. It regulates neural progenitor proliferation and neurogenesis by interacting with a H3K4 methyltransferase complex. Biallelic pathogenic ZNF335 variants predispose to neuronal cell death and aberrant differentiation, thus causing secondary microcephaly. These neurodevelopmental anomalies lead to imaging findings in the cortex, posterior fossa, and basal ganglia. We report an individual of Nepalese ancestry with a novel homozygous ZNF335 variant (c.3591 + 2dup) (p.?) (NM_022095.3) which on further RNA analysis confirmed a splice site variant in intron 23. The patient presented with primary microcephaly with atrophic cerebral hemispheres, oversimplification of gyri, basal ganglia, and corpus callosal atrophy. Literature review on the topic revealed a spectrum of brain abnormalities, which can present either with a primary or secondary microcephaly depending upon the underlying genetic variant.

OBJECTIVE: To find out whether inclisiran sodium has different efficacy in heterozygous familial hypercholesterolemia (HeFH) and homozygous familial hypercholesterolemia (HoFH) patient groups.
METHODS: We conducted the systematic review and meta-analysis of ORION clinical trials. PubMed, Embase, and Clinicaltrials.gov databases were searched for the relevant studies. Atheroscalerotic parameters considered for our objective were low-density lipoprotein cholesterol, total cholesterol, proprotein convertase subtilisin/kexin type 9 (PCSK9), apolipoprotein B, and nonhigh-density lipoprotein cholesterol. Primary outcomes were the percentage difference in atheroscalerotic parameters at follow-up relative to baseline values. Our study examined these primary outcomes to determine whether there is a statistically significant difference between the HeFH and HoFH groups. Risk of bias was assessed by the Cochrane risk of bias tool. Meta-analysis was performed when at least 2 studies reported on the same variable.
RESULTS: Four ORION clinical trials provided the data related to the mean difference in the atheroscalerotic parameters at follow-up relative to baseline, of HeFH and HoFH patient populations, after administration of 300 mg inclisiran subcutaneously. We pooled together these mean differences for each group and applied a statistical test to analyze if the values were significantly different between the groups. The results of our study unveiled the significant difference in pooled mean differences in low-density lipoprotein cholesterol (HeFH: -48.62%; HoFH: -9.12%; P < 0.05), total cholesterol (HeFH: -30.31%; HoFH: -11.50%; P < 0.05), apolipoprotein (HeFH: -39.97%; HoFH: -14.68%; P < 0.05), and nonhigh-density lipoprotein (HeFH: -44.51%; HoFH: -12.22%; P < 0.05) between HeFH and HoFH groups. However, the difference in pooled mean difference in PCSK9 values (HeFH: -68.41%; HoFH: -56.25%; P = 0.2) between HeFH and HoFH groups was statistically insignificant. Studies were of high quality.
CONCLUSIONS: There was a significant difference in the reductions in atherosclerotic lipid parameters in heterozygous and homozygous populations after the administration of inclisiran except for PCSK9 parameter. Further studies are needed to support this conclusion.

Netherton syndrome (NS) is a rare autosomal recessive genodermatosis. In this article, we present two siblings with NS who harbour a novel variant in the SPINK5 gene and were treated with infliximab infusions. Both patients exhibited the characteristic clinical triad of NS, and their whole exome sequencing analysis revealed a homozygous variant, c.1820+53G>A, in the SPINK5 gene. Notably, this is the first documented instance of homozygosity for this particular variant. Despite the absence of a specific treatment, both patients achieved total clearance of the skin lesions, and a significant decrease in total IgE levels was documented.

OBJECTIVE: To explore the genetic etiology of a child with delayed growth and development and carry out a literature review.
METHODS: A child suspected for Al Kaissi syndrome at the First Affiliated Hospital of Zhengzhou University on March 6, 2021 was selected as the study subject. Following extraction of genomic DNA, the child was subjected to copy number variation sequencing (CNV-seq) and whole exome sequencing (WES), and candidate variants were verified by PCR-agarose gel electrophoresis and quantitative real-time PCR (qPCR). Prenatal diagnosis was conducted on chorionic villi sample upon subsequent pregnancy.
RESULTS: The child, a 6-year-and-4-month-old boy, has dysmorphic features including low-set protruding ears and triangular face, delayed language and intellectual development, and ventricular septal defect. CNV-seq result has found no obvious abnormality, whilst WES revealed homozygous deletion of exons 1 and 2 of the CDK10 gene, which was confirmed by PCR-agarose gel electrophoresis and qPCR. Both of his parents were heterozygous carriers. Prenatal diagnosis using chorionic villi samples suggested that the fetus also carried the heterozygous deletion.
CONCLUSIONS: The clinical features of Al Kaissi syndrome in this child can probably be attributed to the homozygous deletion of exons 1 and 2 of the CDK10 gene.

Biallelic variants of 4-hydroxyphenylpyruvate dioxygenase-like (HPDL) gene have been linked to neurodegenerative disorders ranging from severe neonatal encephalopathy to early-onset spastic paraplegia. We identified a novel homozygous variant, c.340G > T (p.Gly114Cys), in the HPDL gene in two siblings with autosomal recessive hereditary spastic paraplegia (HSP). Despite sharing the same likely pathogenic variant, the older sister had pure HSP, whereas her brother had severe and complicated HSP, accompanied by early-onset mental retardation and abnormalities in magnetic resonance imaging. Given the clinical heterogeneity and potential for treatable conditions in HPDL-related diseases, we emphasize the importance of genetic testing for the HPDL gene.

Pharmacogenetics is a potential approach that can be applied to decline the burden of rivaroxaban\'s ADRs. The current systematic review and meta-analysis aim to identify genetic variants correlated with rivaroxaban exposure and evaluate their importance.
We systematically searched PubMed, Web of Science, and Scopus databases for all observational and interventional studies. The fixed effect method was used to pool the data when the Q-test\'s p value was higher than 0.1. We used random models when the p value was less than 0.1.
Data from ten studies (4721 participants) were analyzed in the current review. Qualitative synthesis from included studies found that two variants of ABCB1 (rs1045642 and rs2032582) and one variant of APOB (rs13306198) are potential contributors to rivaroxaban concentrations. Both wild homozygotes (AA) and heterozygotes (AC) of rs1045642 have significantly lower rivaroxaban concentrations compared to mutated homozygotes (CC) (SMD = 0.516, 95% CI: 0.115 to 0.917; SMD = 0.772, 95% CI: 0.088 to 1.455, respectively). Nevertheless, pooling unadjusted odds ratios did not yield a statistically significant correlation between rivaroxaban ADRs and genetic mutations.
This study revealed that being an AC or CC for rs1045642 is attributed to a considerably higher rivaroxaban level in participants using rivaroxaban. That is to say, rs1045642 is a remarkable predictor of rivaroxaban metabolism. We concluded that identifying rs1045642 before drug administration might decrease ADRs although further studies adjusted for potential confounders are strongly suggested.