Klinefelter syndrome is the most common type of genetic cause of hypogonadism. This syndrome is characterized by the presence of 1 or more extra X chromosomes. Phenotype manifestations of this syndrome are small testes, fibrosis of the seminiferous tubules, inability to produce sperm, gynecomastia, tall stature, decrease of serum testosterone and increases of luteinizing hormone and follicle stimulating hormone. Most patients with Klinefelter syndrome are tall, with slender body compositions, and reports of obesity are rare. We report the case of a 35-yr-old man with hypogonadism and morbid obesity and diabetes mellitus. He had gynecomastia, small testes and penis, very sparse body hair and his body mass index was 44.85. He did not report experiencing broken voice and was able to have erections. We conducted a chromosome study. His genotype was 47,X,+t(X;X)(p22.3;p22.3)del(X)(p11.23q11.2). In this case, the patient was diagnosed as Klinefelter syndrome. He showed rare phenotypes like morbid obesity and average height and the phenotype may be caused by the karyotype and the excess number of X chromosome. Further studies of the relationship between chromosomes and phenotype are warranted.
Adult ; Diabetes Complications/genetics ; Humans ; Karyotyping ; Klinefelter Syndrome/*complications/genetics ; Male ; Obesity, Morbid/*complications/genetics ; Phenotype

OBJECTIVE: To explore the clinical phenotype and genetic etiology of a child with early-onset severe obesity. METHODS: A child who presented at the Department of Endocrinology, Hangzhou Children's Hospital on August 5, 2020 was selected as the study subject. Clinical data of the child were reviewed. Genomic DNA was extracted from peripheral blood samples of the child and her parents. Whole exome sequencing (WES) was carried out on the child. Candidate variants were verified by Sanger sequencing and bioinformatic analysis. RESULTS: This child was a 2-year-and-9-month girl featuring severe obesity with hyperpigmentation on the neck and armpit skin. WES revealed that she has harbored compound heterozygous variants of the MC4R gene, namely c.831T>A (p.Cys277*) and c.184A>G (p.Asn62Asp). Sanger sequencing confirmed that they were respectively inherited from her father and mother. The c.831T>A (p.Cys277*) has been recorded by the ClinVar database. Its carrier frequency among normal East Asians was 0.000 4 according to the 1000 Genomes, ExAC, and gnomAD databases. Based on the guidelines from the American College of Medical Genetics and Genomics (ACMG), it was rated as pathogenic. The c.184A>G (p.Asn62Asp) has not been recorded in the ClinVar, 1000 Genomes, ExAC and gnomAD databases. Prediction using IFT and PolyPhen-2 online software suggested it to be deleterious. Based on the guidelines from the ACMG, it was determined as likely pathogenic. CONCLUSION The c.831T>A (p.Cys277*) and c.184A>G (p.Asn62Asp) compound heterozygous variants of the MC4R gene probably underlay the early-onset severe obesity in this child. Above finding has further expanded the spectrum of MC4R gene variants and provided a reference for the diagnosis and genetic counseling for this family.
Female ; Humans ; Computational Biology ; East Asian People ; Genetic Counseling ; Genomics ; Mutation ; Obesity, Morbid/genetics* ; Child, Preschool ; Pediatric Obesity/genetics*