Hardelin et al. (1993) reported results of a mutation search of the KAL1 gene in 21 unrelated males with familial Kallmann syndrome. In 2 families, large deletions that included the entire KAL gene were detected by Southern blot analysis. By sequencing each of the 14 coding exons and splice site junctions in the other 19 patients, they found 9 point mutations at separate locations in 4 exons and 1 splice site. They emphasized the high frequency of unilateral renal aplasia in X-linked Kallmann syndrome patients; 6 of 11 males with identified alterations of the KAL gene showed this feature.
The StAR protein was first identified, characterized and named by Dr. Douglas Stocco at Texas Tech University Health Sciences Center in 1994.  The role of this protein in lipoid CAH was confirmed the following year in collaboration with Dr. Walter Miller at the University of California, San Francisco .  All of this work follows the initial observations of the appearance of this protein and its phosphorylated form coincident with factors that caused steroid production by Dr. Nanette Orme-Johnson while at Tufts University . 
The majority of cases of recessive XLI are caused by complete deletion of the steroid sulfatase gene ( STS ) on chromosome [ 6,7 ]. Other cases result from partial deletion or point mutations of STS [ 8,9 ] . Deletions or mutations of the STS gene cause complete loss of steroid sulfatase enzyme activity. Affected males inherit the X-chromosome bearing a deleted or mutated gene from their asymptomatic carrier mothers, although rare sporadic cases have been reported [ 10,11 ]. In 5 to 8 percent of cases, the deletion includes genes adjacent to STS, resulting in a number of contiguous gene syndromes [ 12,13 ]. (See 'Contiguous gene syndromes' below.)