Clinical Dysmorphology最新文献

Objectives: To determine the cause of marked hypotonia and neonatal encephalopathy, mild anemia and thrombocytopenia, and nonspecific facial dysmorphism in a neonate after extensive neurological and biochemical evaluations, and karyotyping failed to establish the etiology.

Methods: Whole exome sequencing (WES), single-nucleotide polymorphisms chromosomal microarray (SNPs CMA), and fluorescence in-situ hybridization (FISH) analysis were performed in the patient and the parents.

Results: WES did not show a candidate gene/diagnosis. Trio-CMA and FISH confirmed a de novo 8.9 Mb duplication of 11p15.4p15.5 and a 6.4 Mb deletion of 11q24.3q25 in the child, and that the duplicated 11p was of paternal origin, based on the SNPs analysis. On long-term follow-up, encephalopathy improved gradually, thrombocytopenia resolved, facial puffiness persisted, and developmental delay remained. The present patient represents the first case of de novo 11p duplication with 11q deletion and severe neonatal encephalopathy. The de novo chromosomal rearrangement could still have resulted from nonallelic homologous recombination, triggered by low-copy repeats (LCRs) at distal 11p and 11q during paternal meiosis, despite the lower LCR density. Alternatively, it may represent a random event, as it does not involve the recurrent deletion/duplication typically observed in regions with dense LCRs.

Background: Autosomal recessive spinocerebellar ataxia-13 is a rare multifactorial disorder characterized by physical disability, cerebellar ataxia, adaptive behavior, intellectual disability, response to sudden noise and light, sensation, skeletal, and oculomotor abnormalities. It affects both males and females equally. So far, only seven variants have been identified in the glutamate metabotropic receptor 1 (GRM1) gene in 18 familial cases of Roma, Iranian, Pakistani, and Tunisian origins.

Methods: In the present study, we have investigated a large consanguineous family of Pakistani origin presenting severe phenotypes like intellectual disability, delayed developmental milestones, severe ataxia, and nonprogressive neuropathy. Whole exome sequencing was done, followed by Sanger sequencing.

Results: Sequence analysis revealed a novel homozygous deletion mutation (c.1715del) in the GRM1 gene (NM_001278064.2) that led to the substitution of Asn with Met at the 572 amino acid position, leading to frame shift and premature termination (p. Asn572MetfsTer4).

Conclusion: This study raised the total number of GRM1 variants to eight and would be helpful in prenatal screening, genetic counseling, and carrier testing of other members in the Pakistani community.

Objective: Kosaki overgrowth syndrome (KOGS) is a rare genetic disorder linked to germline variants in the platelet-derived growth factor receptor beta gene ( PDGFRB ) that is characterized by postnatal overgrowth, hyperelastic skin, lipodystrophy, and craniofacial anomalies. This study aimed to summarize clinical and genetic data from reported KOGS cases and investigate the molecular consequences of two recurrent KOGS-associated PDGFRB variants.

Methods: Clinical and genetic information from 17 previously published KOGS cases was reviewed. Molecular studies were performed using patient-derived fibroblasts and genetically modified cells transduced with the recurrent PDGFRB variants Trp566Arg and Pro584Arg. Downstream signaling and phosphorylation of PDGFRβ tyrosine residues were assessed by immunoblotting and immunocytochemistry.

Results: Both variants induced phosphorylation of specific PDGFRβ tyrosine residues and activated downstream signaling pathways in the absence of ligand stimulation, which could contribute to the phenotypic overgrowth observed in KOGS. Immunocytochemistry revealed vesicle-like structures of phosphorylated PDGFRβ (pY740), resembling wild-type cells stimulated with growth factor, thereby supporting the constitutive activation of PDGFRβ in patient fibroblasts. Both variants showed sensitivity to the tyrosine kinase inhibitor imatinib.

Conclusion: Recurrent PDGFRB variants in KOGS cause ligand-independent activation of PDGFRβ, contributing to the overgrowth phenotype. Imatinib may represent a potential targeted therapeutic option.