Objective:To explore the clinical manifestations and genetic characteristics of Wolf-Hirschhorn syndrome (WHS) to improve the ability of diagnosis and differential diagnosis of the disease.Methods:The clinical features and auxiliary examinations and treatment of a proband with WHS caused by microdeletion of 4p16.3 segment who admitted to the Third Affiliated Hospital of Zhengzhou University in December 2021 were recorded, and whole exome sequencing (WES) of the family was performed. The prognosis was followed up.Results:The female proband, 11 months old, presented with convulsions at the age of 8 months, with the characteristics of heat sensitivity and cluster seizures, and her identical twin sister had a similar medical history. Physical examination found malnutrition, retarded development, special face, prominent forehead, wide nasal bridge, small jaw, precordial murmur and grade 3/6 murmur in the whole period, hyperactivity of P2, and low limb muscle tone. The whole exon and copy number variation (CNV) test of the family revealed that the proband had a 1.99 Mb heterozygous deletion in the chromosome 4p16.3 segment, including WHSC1 (NSD2), WHSC2 (NEFLA) and other genes. Copy number variation sequencing (CNV-Seq) of the proband and her sister showed 1.97 and 1.92 Mb heterozygous deletion of chromosome 4p16.3, respectively. Genealogical analysis by quantitative polymerase chain reaction revealed that the CNV was de novo, and it was determined to be a pathogenic variant according to the American College of Medical Genetics and Genomics guidelines. The proband took sodium valproate orally, and her sister took oral sodium valproate, zonisamide, and levetiracetam successively, and at the same time they received family rehabilitation training. The age at the last follow-up was 1 year and 8 months. Neither of them had convulsions again in the past 3 months, but the developmental delay was obvious. Conclusion:WHS patients may present with growth retardation, epilepsy, Greek warrior helmet-like special face, and congenital heart disease, and may have microdeletions in the chromosome 4p16.3 segment.

Objective:To summarize the clinical and genetic features of children with intellectual developmental disorder with seizures and language delay (IDDSELD) due to 12q24.31 deletion and SETD1B locus variants. Methods:The clinical data of a child with 12q24.31 deletion diagnosed in the Department of Pediatric Neurology of the Third Affiliated Hospital of Zhengzhou University in September 2022 were retrospectively analyzed. Trio-whole exome sequencing (trio-WES) and copy number variations sequencing (CNV-seq) were used for genetic analysis. The relevant literatures were reviewed to summarize the clinical features of the disease.Results:The proband was a 7 years and 9 month old girl who had clinical features of global developmental delay, epilepsy, hyperactivity, hypertonia, gait disorder, special facial features (high eyebrow arch, big ears, upper lip protrusion), funnel chest, lumbar lordosis. Karyotypic analysis showed 46XX in the proband. CNV-seq showed 12q24.31 (chr12: 121895654-122449092) position had a deletion of about 553.44 kb which contained the SETD1B gene. Trio-WES showed deletion of all exons 1-16 of the SETD1B gene. CNV-seq results of her parents were normal: the SETD1B gene was wild-type. This type has not been reported in China. Four children with IDDSELD caused by 12q24.31 deletion (including the SETD1B gene) were retrieved (totally 5 cases including this case), with male to female ratio of 1∶4, all with de novo mutations, and all with mental retardation, cephalo-facial and skeletal malformations. Three cases had seizures, 2 cases still had developmental backwardness after treatment, and 1 case was seizure controlled. Forty-seven cases of IDDSELD due to point mutation in the SETD1B gene were retrieved: male to female ratio was 31∶16, missense mutations (38/47) were predominant, most were de novo mutations (36/47), and a few were inherited from their fathers/mothers (6/47) or of unknown origin (5/47), with clinical manifestations of speech delay (43/47), growth retardation (43/47), intellectual disability (37/41), behavioral problems (37/47), facial malformations (34/47), skeletal malformations (23/47), obesity (16/47), skin abnormalities (11/47), etc. Thirty-nine cases were combined with seizures, 23 of whom were under control after treatment, and 8 cases were recorded as still having developmental backwardness after treatment. Conclusions:IDDSELD patients are rare at home and abroad, with diverse clinical phenotypes and difficult diagnosis. Symptomatic treatment is the main approach. And the patients can leave behind seizures and varying degrees of developmental backwardness. Among them, patients with 12q24.31 deletion are relatively rare and have not been reported in China, and this type is more common in females, all of whom have de novo mutations, and genetic testing is helpful for the early diagnosis of IDDSELD.