[Clinical and genetic characteristics analysis of two children with comorbidity of two rare genetic diseases].

Abstract

Objective: To explore the clinical and genetic characteristics of two children diagnosed with two rare genetic diseases simultaneously.

Methods: Two children with comorbidity of two genetic diseases due to dual genetic mutations diagnosed at the Third Affiliated Hospital of Zhengzhou University respectively in May 2022 and March 2023 were selected as the study subjects. Clinical and genetic data of the two children were retrospectively analyzed. This study has been approved by the Ethics Committee of the Third Affiliated Hospital of Zhengzhou University (Ethic No. 2021-062-01).

Results: Child 1 was a 2-year-and-4-month-old boy whose clinical manifestations included facial dysmorphism, developmental delay, short stature, microcephaly, cleft palate, cryptorchidism, hypospadias, recurrent infections and immunological abnormalities. Whole exome sequencing revealed that he had harbored a heterozygous c.6595delT (p.Y2199Ifs*65) variant of the KMT2D gene and a heterozygous c.1892G>A (p.R631Q) variant of the PIK3R1 gene. This has led to a dual genetic diagnosis of Kabuki syndrome and PI3Kδ-related immunodeficiency type 36. Child 2 was a 15-year-old girl whose clinical manifestations included epilepsy, Albright's hereditary osteodystrophy, long body trunk, short limbs, hypocalcemia, hyperphosphatemia and hyperparathyroidism. The child also had a family history of short stature. Whole exome sequencing revealed that she had harbored a heterozygous c.2T>C (p.Met1?) variant of the GNAS gene and deletion of exons 2 to 6 of the SHOX gene. The two variants have led to dual diagnose of pseudohypoparathyroidism and X-linked idiopathic short stature.

Conclusion: When the clinical phenotype of a genetic disease is complex and cannot be fully explained with a single genetic variant, multiple pathogenic variants should be considered, and this may lead to the diagnosis of co-morbid genetic diseases. To adopt or supplement corresponding genetic testing in time and re-analyze the genetic data may facilitate accurate diagnosis of co-morbid genetic diseases.