SAT-285 Role of Chromosome Microarray in Identifying a Genetic Cause of Undervirilized External Genitalia and Growth Delay in an Infant: 6p Duplication Associated with Short Stature and Micropenis

THE CASE 4 mo M born at term 7lbs 7.5oz, 19.5 inches via C-section, referred for micropenis found during evaluation for circumcision. No history of hypoglycemia. Of note, dad is s/p hypospadias repair and is short at 5th %ile. PE showed short stature, length at 3rd %ile (-1.91 SDS), wt 53rd %ile, HC 76th %ile. Stretched penile length 1.5 cm (-2.5 SDS = 1.9cm), testes 1.5 cm each, normal. Periorbital hemangioma noted. Otherwise normal exam. Chromosome microarray showed a 6.1 Mb duplication of the terminal region of 6p, pathogenic; and a 222 kb deletion of terminal 17p (felt to have no clinical significance). Patient referred to Genetics. Parental testing showed balanced translocation in dad's chromosome 46,XY,t(6;17)(p25.1;p13.1)]. GH, TSH, FT4, LH, FSH, AMH levels normal. Total Testosterone 68 ng/dL. CAH-6 panel within expected limits. Testosterone therapy 50mg/mo x 3mos initiated to improve penile length. DISCUSSION Workup of underlying cause of male undervirilization is challenging. More often than not, a definitive diagnosis remains elusive. The current case underlines the invaluable contribution of chromosomal microarray in this endeavor. Duplication of distal fragment of chromosome 6p is extremely rare, with