To describe clinical and behavioral features of 10 men from 2 families with Borjeson-Forssman-Lehmann syndrome (BFLS) and missense mutations in the PHF6 zinc-finger transcription factor gene.

BFLS behavioral features were compared with other age-matched men with other syndromes and similar intellectual functioning through the use of standardized questionnaires: the Child Behavior Checklist, the Vineland Adaptive Behavior Scales, and the Reiss Personality Profile. Participants included 10 with BFLS, 10 with Prader-Willi syndrome, and 23 with Klinefelter syndrome variants (13 with 48,XXYY, 4 with 48,XXXY, and 6 with 49,XXXXY).

Contrary to initial reports, our men with BFLS had no microcephaly, seizures, or short stature. They manifested deep-set eyes with large ears, coarse facial features, small external genitalia, gynecomastia, and obesity. Family A had mild to moderate mental retardation, whereas family B was more severely affected. On Vineland Adaptive Behavior Scales, men with BFLS had higher daily living and social skills than communicative skills. Men with BFLS also had lower internalizing and externalizing symptoms and appeared more social and helpful than men with Prader-Willi syndrome or Klinefelter syndrome variant.

Men with BFLS from 2 families with mutations in the PHF6 gene manifested distinctive clinical features and a low risk for maladaptive behaviors.