Disorders of sex development (DSD) are congenital conditions with atypical development of chromosomal, gonadal, or anatomical sex. The estimated incidence ranges from 1 in 4,500-5,500 for strictly defined "ambiguous genitalia" to 1 in 300 or higher when a broader definition is implemented. In this study, we aim to define DSD phenotypes encountered in a large heterogeneous cohort of molecularly characterized Mendelian disorders in a single center. Data were retrieved for patients with documented abnormal genitalia based on the 2006 consensus criteria. Out of 149 patients (129 families) with compatible human phenotype ontology, 76 patients (68 families) had an identified genetic cause and were included in our analysis. Potentially causal variants were identified in 42 genes, and two patients had a dual molecular diagnosis. Six genes have no associated phenotype in OMIM (PIANP, CELSR2, USP2, FAM179B, TXNDC15, and CCDC96). Thirteen genes have non-DSD OMIM phenotypes, thus we are expanding their phenotype to include DSD. We also highlight how certain disorders are under-recognized despite their established DSD phenotype in OMIM, especially CTU2-related DREAM-PL syndrome and TSPYL1-related sudden infant death with dysgenesis of the testes syndrome. In conclusion, this study of a large heterogeneous Mendelian cohort expands the list of genes and disorders beyond those classically DSD-linked. K E Y W O R D S ambiguous genitalia, differences in sex development, sex reversal 1 | INTRODUCTION Disorders of sex development (DSD) are defined as congenital conditions in which development of chromosomal, gonadal, or anatomical sex is atypical (Lee et al., 2016). The clinical phenotypes of these disorders are heterogenous and include micropenis, cryptorchidism, clitoromegaly and, in more severe cases, ambiguous genitalia. The exact incidence can be challenging to determine accurately due to discrepancy in the definition used by the different epidemiological studies and the changes in classification over time. However, it is estimated to be 1 in 4,500-5,500 for strictly defined "ambiguous genitalia" and increases to 1 in 300 or higher if a broader definition is used (