Two novel pathogenic variants in the TCOF1 found in two Chinese cases of Treacher Collins syndrome.

BACKGROUND: Treacher Collins Ι syndrome (TCS1, OMIM:154500) is an autosomal dominant disease with a series of clinical manifestations such as craniofacial dysplasia including eye and ear abnormalities, small jaw deformity, cleft lip, as well as repeated respiratory tract infection and conductive hearing loss. Two cases of Treacher Collins syndrome with TCOF1(OMIM:606847) gene variations were reported in the article, with clinical characteristics, gene variants and the etiology. METHODS: The clinical data of two patients with Treacher Collins syndrome caused by TCOF1 gene variation were retrospectively analyzed. The whole exome sequencing (WES) was performed to detect the pathogenic variants of TCOF1 gene in the patients, and the verification of variants were confirmed by Sanger sequencing. RESULTS: Proband 1 presented with bilateral craniofacial deformities, conductive hearing loss and recurrent respiratory tract infection. Proband 2 showed bilateral craniofacial malformations with cleft palate, which harbored similar manifestations in her family. She died soon after birth due to dyspnea and feeding difficulties. WES identified two novel pathogenic variants of TCOF1 gene in two probands, each with one variant. According to the American College of Medical Genetics and Genomics, the heterozygous variation NM_001371623.1: c.877del (p. Ala293Profs*34) of TCOF1 gene was detected in Proband 1, which was evaluated as a likely pathogenic (LP) and de novo variant. Another variant found in Proband 2 was NM_001135243.1: c.1660_1661del (p. D554Qfs*3) heterozygous variation, which was evaluated as a pathogenic variation and the variant inherited from the mother. To date, the two variants have not been reported before. CONCLUSION: Our study found two novel pathogenic variants of TCOF1 gene and clarified the etiology of Treacher Collins syndrome. We also enriched the phenotypic spectrum of Treacher Collins syndrome and TCOF1 gene variation spectrum in the Chinese population, and provided the basis for clinical diagnosis, treatment and genetic counseling.

[Analysis of genetic variants and clinical manifestations of two children with Kabuki syndrome].

OBJECTIVE: To report on two children with Kabuki syndrome due to variants of the KMT2D gene and summarize their clinical and genetic characteristics. METHODS: Two children who had presented at the Ningbo Women and Children's Hospital respectively on August 19 and November 10, 2021 were selected as the study subjects. Clinical data were collected. Both children were subjected to whole exome sequencing (WES), and candidate variants were validated by Sanger sequencing. RESULTS: Both children had featured motor and language developmental delay, facial dysmorphism and mental retardation. Genetic testing revealed that both had harbored de novo heterozygous variants of the KMT2D gene, namely c.10205del (p.Leu3402Argfs*3) and c.5104C>T (p.Arg1702*), both of which were rated as pathogenic variants based on the guidelines from the American College of Medical Genetics and Genomics (ACMG). CONCLUSION: The c.10205del (p.Leu3402Argfs*3) and c.5104C>T (p.Arg1702*) variants of the KMT2D gene probably underlay the pathogenesis in these two children. Above finding has not only provided a basis for their diagnosis and genetic counseling, but also enriched the spectrum of KMT2D gene variants.

[A prospective study of genetic screening of 2 060 neonates by high-throughput sequencing].

OBJECTIVE: To assess the value of genetic screening by high-throughput sequencing (HTS) for the early diagnosis of neonatal diseases. METHODS: A total of 2 060 neonates born at Ningbo Women and Children's Hospital from March to September 2021 were selected as the study subjects. All neonates had undergone conventional tandem mass spectrometry metabolite analysis and fluorescent immunoassay analysis. HTS was carried out to detect the definite pathogenic variant sites with high-frequency of 135 disease-related genes. Candidate variants were verified by Sanger sequencing or multiplex ligation-dependent probe amplification (MLPA). RESULTS: Among the 2 060 newborns, 31 were diagnosed with genetic diseases, 557 were found to be carriers, and 1 472 were negative. Among the 31 neonates, 5 had G6PD, 19 had hereditary non-syndromic deafness due to variants of GJB2, GJB3 and MT-RNR1 genes, 2 had PAH gene variants, 1 had GAA gene variants, 1 had SMN1 gene variants, 2 had MTTL1 gene variants, and 1 had GH1 gene variants. Clinically, 1 child had Spinal muscular atrophy (SMA), 1 had Glycogen storage disease II, 2 had congenital deafness, and 5 had G6PD deficiency. One mother was diagnosed with SMA. No patient was detected by conventional tandem mass spectrometry. Conventional fluorescence immunoassay had revealed 5 cases of G6PD deficiency (all positive by genetic screening) and 2 cases of hypothyroidism (identified as carriers). The most common variants identified in this region have involved DUOX2 (3.93%), ATP7B (2.48%), SLC26A4 (2.38%), GJB2 (2.33%), PAH (2.09%) and SLC22A5 genes (2.09%). CONCLUSION: Neonatal genetic screening has a wide range of detection and high detection rate, which can significantly improve the efficacy of newborn screening when combined with conventional screening and facilitate secondary prevention for the affected children, diagnosis of family members and genetic counseling for the carriers.