Isolated Growth Hormone Deficiency (IGHD) due to GH1 gene defects has a variable inheritance pattern: autosomal recessive, autosomal dominant, and X-linked. the autosomal dominantly inherited form, IGHD II, is mainly caused by heterozygous mutations of splicing around the exon 3/IVs3 boundary region of the GH1 gene resulting in exon 3 skipping of transcripts. We have previously reported findings on GH1 gene mutations in 28 russian patients with severe congenital IGHD (-3.22+/-1.2 height sDs at the age of 1yr); five heterozygous dominant negative splice site mutations in intron 2, intron 3, and exon 4 of the GH1 gene were identified in 32.1% of the cohort. In the present report we describe a novel 456G>A heterozygous mutation of splicing of the last base of the 3'-acceptor splice site of exon 4 within the GH1 in a 4.2-year old, extremely short (-5.32 height sDs) girl with congenital IGHD. the mutation involves a highly conserved GGGgtg sequence of the exon 4/IVs4 boundary region of the GH1 gene. the predicted effect of the 456 G>A mutation is perturbed splicing with possible skipping of exon 4 of the GH1 gene. the novel heterozygous 456 G>A mutation in exon 4 expands the spectrum of dominant negative splicing defects within the GH1 gene, responsible for congenital IGHD.