Gene dosage studies supporting localization of the structural gene for galactose‐1‐phosphate uridyl transferase (GALT) to band p13 of chromosome 9

A newborn male was diagnosed as having a duplication of distal 9p material by GTG banding analysis. Gene dose studies for galactose-1-phosphate uridyl transferase (GALT) were performed on the patient, his mother (the balanced translocation carrier), a 3-year-old 47,XY + 9p male control, a 30-year-old woman with mosaic trisomy 9p, a newborn female control infant with complete trisomy 9, and age-matched chromosomally normal control individuals. The findings support previous evidence that the GALT locus is at band p13 of chromosome 9.