diff --git a/.DS_Store b/.DS_Store
index 32ed297..a2308d9 100644
Binary files a/.DS_Store and b/.DS_Store differ
diff --git a/VariantFormatter/variantformatter.py b/VariantFormatter/variantformatter.py
index cab0279..a360af0 100644
--- a/VariantFormatter/variantformatter.py
+++ b/VariantFormatter/variantformatter.py
@@ -66,6 +66,8 @@ def __init__(self, p_vcf, g_hgvs, un_norm_hgvs, hgvs_ref_bases, gen_error, genom
         try:
             if ("NC_012920.1" in str(g_hgvs)) and "hg19" in genome_build:
                 gen_error = "NC_012920.1 is not associated with genome build hg19, instead use genome build GRCh37"
+            elif ("NC_001807.4" in str(g_hgvs)) and "GRCh37" in genome_build:
+                gen_error = "NC_001807.4 is not associated with genome build GRCh37, instead use genome build hg19"
         except TypeError:
             pass