BackgroundHao-fountain syndrome (HAFOUS) is a neurodevelopmental syndrome characterized by global developmental and severe language delays, behavioral abnormalities (including autism), and mild dysmorphic impairment of intellectual development. It is a dominant genetic disease caused by USP7 gene (*602519) mutations on chromosome 16p13.2. So far, only 15 cases with 14 deleterious variants in the USP7 gene have been reported.Materials and methodsThis study describes three unrelated patients with USP7 variants. Besides, we identified novel de novo heterozygous USP7 variants using trio-whole exome sequencing and verified by Sanger sequencing. Furthermore, clinical characteristics were evaluated by reviewing the medical records.ResultsThe three identified variants, i.e., one frameshift variant (c.247_250del, p.Glu83Argfs × 18) and two missense variants (c.992A > G, p.Tyr331Cys; c.835T > G, p.Leu279Val) are unreported. The predominant clinical manifestations of the three patients included: DD/ID; language impairment; abnormal behavior; abnormal brain magnetic resonance (dilation of lateral ventricles, dilation of Virchow-Robin spaces, dilated the third ventricle, abnormal cerebral white matter morphology in bilateral occipital lobes, hypodysplasia of the corpus callosum, arachnoid cyst, delayed myelination, and widened subarachnoid space); some also had facial abnormalities.ConclusionIn summary, DD/ID is the most prevalent clinical phenotype of HAFOUS, although some patients also exhibit language and behavioral abnormalities. For the first time in China, we identified three variants of the USP7 gene using whole-genome sequence data. This work expands the USP7 gene mutation spectrum and provides additional clinical data on the clinical phenotype of HAFOUS.
Developmental and epileptic encephalopathies (DEE) caused by heterozygous deleterious variants in Cut Like Homeobox2 (CUX2) is rare. To the best of our knowledge the only variant associated with a phenotype in this gene is the de novo missense variant c.1768G > A, p.Glu590Lys; however, further additional research is needed to characterize the relationship between disease and variants in this gene. In this study, we reported a patient from a non-consanguineous Chinese family presenting with epilepsy, developmental delay, and speech delay. Additionally, the patient responded well to levetiracetam, and at his last follow-up (5.5 years old), he had discontinued antiepileptic drug treatment and remained seizure-free for 6 months. To identify possible causative variants, trio-whole exome sequencing was performed. We identified a novel de novo missense CUX2 c.2834C > T, p. Thr945Met variant in the patient. Based on clinical and genetics information associated with the bioinformatics analyses, we hypothesized that this variant was the cause of the reported phenotype. AlphaFold and SWISS-MODEL homology modeling servers were used to predict the three-dimensional (3D) structure of CUX2 protein. Predictions based on the 3D-structure modeling indicated that the p.Thr945Met substitution was likely to alter the DNA-binding specificities and affect protein function. On the basis of clinical characteristics and genetic analysis, we presented one case diagnosed with DEE67. Our finding expanded the clinical and molecular spectrum of CUX2 variants.
ObjectivesGalloway–Mowat syndrome-4 (GAMOS4) is a very rare renal-neurological disease caused by TP53RK gene mutations. GAMOS4 is characterized by early-onset nephrotic syndrome, microcephaly, and brain anomalies. To date, only nine GAMOS4 cases with detailed clinical data (caused by eight deleterious variants in TP53RK) have been reported. This study aimed to examine the clinical and genetic characteristics of three unrelated GAMOS4 patients with TP53RK gene compound heterozygous mutations.MethodsWhole-exome sequencing (WES) was used to identify four novel TP53RK variants in three unrelated Chinese children. Clinical characteristics such as biochemical parameters and image findings of patients were also evaluated. Furthermore, four studies of GAMOS4 patients with TP53RK variants were reviewed. In addition, clinical and genetic features were described after a retrospective analysis of clinical symptoms, laboratory data, and genetic test results.ResultsThe three patients showed facial abnormalities, developmental delays, microcephaly, and aberrant cerebral imaging. Furthermore, patient 1 had slight proteinuria, while patient 2 had epilepsy. However, none of the individuals had nephrotic syndrome, and all were alive for more than 3 years of age. This is the first study to assess four variants in the TP53RK gene (NM_033550.4: c.15_16dup/p.A6Efs*29, c.745A > G/p.R249G, c.185G > A/p.R62H, and c.335A > G/p.Y112C).ConclusionThe clinical characteristics of the three children with TP53RK mutations are significantly different from the known GAMOS4 traits, including early nephrotic syndrome and mortality mainly occurring in the first year of life. This study provides insights into the pathogenic TP53RK gene mutation spectrum and clinical phenotypes of GAMOS4.
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