Phenotypic variability and management of patients with mosaic monosomy X and Y chromosome material: a case series

Ital J Pediatr. 2024 May 7;50(1):93. doi: 10.1186/s13052-024-01618-9.


Background: we aim to discuss the origin and the differences of the phenotypic features and the management care of rare form of disorder of sex development due to Mosaic monosomy X and Y chromosome materiel.

Methods: We report our experience with patients harboring mosaic monosomy X and Y chromosome material diagnosed by blood cells karyotypes and cared for in our department from 2005 to 2022.

Results: We have included five infants in our study. The current average age was 8 years. In four cases, the diagnosis was still after born and it was at the age of 15 years in one case. Physical examination revealed a variable degree of virilization, ranging from a normal male phallus with unilateral ectopic gonad to ambiguous with a genital tubercle and bilateral not palpable gonads in four cases and normal female external genitalia in patient 5. Karyotype found 45, X/46, XY mosaicism in patient 1 and 2 and 45, X/46, X, der (Y) mosaicism in patient 3, 4 and 5. Three cases were assigned to male gender and two cases were assigned to female. After radiologic and histologic exploration, four patients had been explored by laparoscopy to perform gonadectomy in two cases and Mullerian derivative resection in the other. Urethroplasty was done in two cases of posterior hypospadias. Gender identity was concordant with the sex of assignment at birth in only 3 cases.

Conclusion: Because of the phenotypic heterogeneity of this sexual disorders and the variability of its management care, then the decision should rely on a multidisciplinary team approach.

Keywords: 45X; 46; 46XY; 45X; Der(Y); mosaicism; phenotype; Monosomy; Disorder of sex development; X.

MeSH terms

  • Adolescent
  • Child
  • Child, Preschool
  • Chromosomes, Human, X / genetics
  • Chromosomes, Human, Y* / genetics
  • Disorders of Sex Development / diagnosis
  • Disorders of Sex Development / genetics
  • Disorders of Sex Development / therapy
  • Female
  • Humans
  • Infant
  • Karyotyping
  • Male
  • Monosomy / genetics
  • Mosaicism*
  • Phenotype*
  • Turner Syndrome / genetics
  • Turner Syndrome / therapy