Clinical and genetic characteristics of 9 rare cases with coexistence of dual genetic diagnoses / 中华儿科杂志

Objective: To analyze the clinical and genetic characteristics of pediatric patients with dual genetic diagnoses (DGD). Methods: Clinical and genetic data of pediatric patients with DGD from January 2021 to February 2022 in Peking University First Hospital were collected and analyzed retrospectively. Results: Among the 9 children, 6 were boys and 3 were girls. The age of last visit or follow-up was 5.0 (2.7,6.8) years. The main clinical manifestations included motor retardation, mental retardation, multiple malformations, and skeletal deformity. Cases 1-4 were all all boys, showed myopathic gait, poor running and jumping, and significantly increased level of serum creatine kinase. Disease-causing variations in Duchenne muscular dystrophy (DMD) gene were confirmed by genetic testing. The 4 children were diagnosed with DMD or Becker muscular dystrophy combined with a second genetic disease, including hypertrophic osteoarthropathy, spinal muscular atrophy, fragile X syndrome, and cerebral cavernous malformations type 3, respectively. Cases 5-9 were clinically and genetically diagnosed as COL9A1 gene-related multiple epiphyseal dysplasia type 6 combined with NF1 gene-related neurofibromatosis type 1, COL6A3 gene-related Bethlem myopathy with WNT1 gene-related osteogenesis imperfecta type XV, Turner syndrome (45, X0/46, XX chimera) with TH gene-related Segawa syndrome, Chromosome 22q11.2 microduplication syndrome with DYNC1H1 gene-related autosomal dominant lower extremity-predominant spinal muscular atrophy-1, and ANKRD11 gene-related KBG syndrome combined with IRF2BPL gene-related neurodevelopmental disorder with regression, abnormal movement, language loss and epilepsy. DMD was the most common, and there were 6 autosomal dominant diseases caused by de novo heterozygous pathogenic variations. Conclusions: Pediatric patients with coexistence of double genetic diagnoses show complex phenotypes. When the clinical manifestations and progression are not fully consistent with the diagnosed rare genetic disease, a second rare genetic disease should be considered, and autosomal dominant diseases caused by de novo heterozygous pathogenic variation should be paid attention to. Trio-based whole-exome sequencing combining a variety of molecular genetic tests would be helpful for precise diagnosis.

Analysis of 4 children with DYNC1H1 gene related spinal muscular atrophy with lower extremity predominant 1 / 中华儿科杂志

Objective: To investigate the clinical features and gene variation characteristics of children with dynein cytoplasmic 1 heavy chain 1 (DYNC1H1) gene associated spinal muscular atrophy with lower extremity predominant (SMALED) 1. Methods: The clinical data of 4 SMALED1 children admitted to Peking University First Hospital from December 2018 to May 2021, who were found to have pathogenic variation of DYNC1H1 gene through genetic testing, except for other genes known to be related to motor retardation, were retrospectively summarized to analyze the phenotype and genotype characteristics. Results: There were 3 males and 1 female. The age of onset was 1 year, 1 day, 1 day and 4 months, respectively. The age of diagnosis was 4 years and 10 months, 9 months, 5 years and 9 months, and 3 years and 1 month, respectively. The clinical manifestations were muscle weakness and muscular atrophy of lower limbs, 2 cases with foot deformity, 1 case with early non progressive joint contracture, 1 case with hip dislocation and 1 case with mental retardation. De novo heterozygous missense variations in DYNC1H1 gene were found in all 4 children. According to the rating of American College of medical genetics and genomics, they were all possible pathogenic and pathogenic variations, with p.R598C, p.P776L, p.Y1109D variations had been reported, and p.I1086R variation had not been reported. Conclusions: For those with unexplained lower limb muscle weakness, muscle atrophy, joint contracture and foot deformity, upper limb motor ability related retention, with or without mental retardation, as well as the motor ability progresses slowly, it is necessary to consider the possibility of SMALED1 and the detection of DYNC1H1 gene when necessary.

Phenotype/genotype analysis of 4 cases of LMNA related congenital muscular dystrophy with inflammatory changes / 中华实用儿科临床杂志

Objective To analyze the clinical characteristics,muscle pathological features and pathogenic gene mutation in 4 cases with LMNA-related congenital muscular dystrophy (L-CMD).Methods Clinical data of the probands and the parents were collected.Skeletal muscle specimens were biopsied from the probands for pathological analysis.Genomic DNA and RNA were extracted from peripheral blood leukocytes,and PCR,reverse transcription(RT)-PCR and DNA direct sequencing were employed to analyze the LMNA gene to determine the gene mutation and confirm the pathogenicity.Results Four patients had symptoms from fetal period to several months after birth.They presented with motor retardation,muscle weakness with prominent the proximal upper limbs,distal lower limbs and neck extensor,hypotonia,contractures,with mild to moderate elevation of CK level.The muscle biopsies showed muscular dystrophic and with inflammatory changes,and the abnormal nuclear morphology was observed with transmission electron microscopy.Genetic analysis of them detected 4 dominant de novo mutations.Three of them had unreported pathogenic mutations.The same sites of the LMNA gene were wild type in their parents.Conclusions Four cases of L-CMD are genetically identified.Genetic counseling of the family can be possible.The patients should be considered LMNA gene mutation of they present themselves with muscle weakness with the proximal upper limbs,distal lower limbs and neck extensor,hypotonia,contractures,mild to moderate elevation of CK level,and if the biopsies show muscular dystrophic changes but also with inflammatory changes should be considered LMNA gene mutation.Genetic analysis is the most reliable method for diagnosing L-CMD.

A family with autosomal dominant Emery-Dreifuss muscular dystrophy and literature review / 中华实用儿科临床杂志

Objective To analyze the clinical characteristics,muscle pathological features and pathogenic gene mutation of a family with autosomal dominant Emery-Dreifuss muscular dystrophy (AD-EDMD).Methods Clinical data of the proband and her family members,a Chinese family of AD-EDMD,were collected.Skeletal muscle specimens were collected from the proband for pathological analysis.Genomic DNA from the proband and her parents was extracted using standard procedures from the peripheral blood leukocytes.PCR and DNA direct sequencing were employed to analyze all of the 12 exons of the LMNA gene to determine the gene mutation,and the case was summarized along with related literature review.Results The proband,female,4 years and 5 months old now,presented with muscle weakness during her early childhood,the proximally was more prominent,mild pectus excavatum.Her CK level was elevated,her electromyogram showed myogenic injuries,the muscle biopsy showed myopathy changes.Her father had the same symptom,with disease progressed,showed elbow contractures in early stage,stiff neck,tight achilles tendon,slowly progressive muscle weakness of the limbs,sinus bradycardia.A heterozygous missense mutation c.1580G ＞ C (p.Arg527Pro) was identified in exon 9 of the LMNA gene in the proband and her father,but not in her mother.This heterozygous missense mutation had been reported as a pathogenic gene mutation.Conclusions The patient who has elbow contractures in early stage,limited neck flexion,spine stiffness,muscle weakness with the proximal upper limbs and distal lower limbs,and arrhythmia,should have an analysis of the LMNA gene.It's important for the early diagnosis of EDMD,assessment of the prognosis,timely and effectively monitoring the changes of arrhythmia,then taking interventions to improve the quality of life and prolong life.So genetic analysis is most reliable method to diagnose EDMD.