diff --git a/src/varity/vcf_to_hgvs/common.clj b/src/varity/vcf_to_hgvs/common.clj
index 1017f60..67d3f26 100644
--- a/src/varity/vcf_to_hgvs/common.clj
+++ b/src/varity/vcf_to_hgvs/common.clj
@@ -69,15 +69,15 @@
       0
       (let [rbases (string/reverse bases)
             n (count bases)
-            step (count (first (repeat-units rbases)))
-            tweak (if (= step 1) #(+ (dec n) %) #(* step %))]
+            step (count (first (repeat-units rbases)))]
         (->> seq*
-             (take (dec pos))
+             (take (+ pos (dec n)))
              reverse
              (partition (count rbases) step)
              (take-while #(= (apply str %) rbases))
              count
-             tweak)))
+             dec
+             (* step))))
     (throw (ex-info "The bases is not found on the position."
                     {:type ::invalid-bases
                      :sequence seq*
@@ -148,10 +148,10 @@
   ([variant seq*]
    (apply-3'-rule variant seq* :forward))
   ([{:keys [pos ref alt] :as variant} seq* direction]
-   (let [[ref-only alt-only offset _] (diff-bases ref alt)
+   (let [[ref-only alt-only offset right-offset] (diff-bases ref alt)
          type* (cond
-                 (and (zero? (count ref-only)) (pos? (count alt-only))) :ins
-                 (and (pos? (count ref-only)) (zero? (count alt-only))) :del
+                 (and (zero? (count ref-only)) (pos? (count alt-only)) (zero? right-offset)) :ins
+                 (and (pos? (count ref-only)) (zero? (count alt-only)) (zero? right-offset)) :del
                  :else :other)]
      (if (#{:ins :del} type*)
        (let [bases (if (string/blank? ref-only) alt-only ref-only)
diff --git a/src/varity/vcf_to_hgvs/protein.clj b/src/varity/vcf_to_hgvs/protein.clj
index 81d9ff7..52ae369 100644
--- a/src/varity/vcf_to_hgvs/protein.clj
+++ b/src/varity/vcf_to_hgvs/protein.clj
@@ -91,7 +91,7 @@
         ref-down-exon-seq1 (subs ref-down-exon-seq1 0 (- nref-down-exon-seq1 (mod nref-down-exon-seq1 3)))
         alt-exon-seq1 (exon-sequence alt-seq cds-start alt-exon-ranges*)
         apply-offset #(or (ffirst (alt-exon-ranges [[% %]] pos ref alt))
-                          (some (fn [[_ e]] (when (<= e %) e)) alt-exon-ranges*))]
+                          (some (fn [[_ e]] (when (<= e %) e)) (reverse alt-exon-ranges*)))]
     {:ref-exon-seq ref-exon-seq1
      :ref-prot-seq (codon/amino-acid-sequence (cond-> ref-exon-seq1
                                                 (= strand :reverse) util-seq/revcomp))
@@ -308,12 +308,14 @@
                      format-alt-prot-seq
                      (subs (dec (+ ppos offset)))
                      (string/index-of "*"))]
-    (mut/protein-frame-shift (mut/->long-amino-acid ref)
-                             (coord/protein-coordinate (+ ppos offset))
-                             (mut/->long-amino-acid alt)
-                             (if (and ter-site (pos? ter-site))
-                               (coord/protein-coordinate (inc ter-site))
-                               (coord/unknown-coordinate)))))
+    (if (= alt \*)
+      (protein-substitution (+ ppos offset) (str ref) (str alt)) ; eventually fs-ter-substitution
+      (mut/protein-frame-shift (mut/->long-amino-acid ref)
+                               (coord/protein-coordinate (+ ppos offset))
+                               (mut/->long-amino-acid alt)
+                               (if (and ter-site (pos? ter-site))
+                                 (coord/protein-coordinate (inc ter-site))
+                                 (coord/unknown-coordinate))))))
 
 (defn- protein-extension
   [ppos pref palt seq-info]
diff --git a/test/varity/vcf_to_hgvs/common_test.clj b/test/varity/vcf_to_hgvs/common_test.clj
index e0e68a6..62ee2ac 100644
--- a/test/varity/vcf_to_hgvs/common_test.clj
+++ b/test/varity/vcf_to_hgvs/common_test.clj
@@ -49,6 +49,9 @@
       "AGGGGGGT" 7 "G" 5
       "AGGGGGGT" 6 "GG" 4
       "AGGGGGGT" 5 "GGG" 3
+      "AGGGGGGT" 4 "GGGG" 2
+      "AGGGGGGT" 3 "GGG" 1
+      "AGGGGGGT" 2 "GGGGG" 0
       "AAGTGTCC" 5 "GT" 2
       "AAGTGTCC" 3 "GT" 0))
   (testing "backward-shift throws exception when inputs are illegal"
@@ -80,7 +83,12 @@
       {:pos 10, :ref "T", :alt "TAGTCTT"} :forward {:pos 20, :ref "C", :alt "CTTAGTC"}
       {:pos 4, :ref "CAGTCTT", :alt "C"} :forward {:pos 14, :ref "CTTAGTC", :alt "C"}
       {:pos 13, :ref "T", :alt "TCTTAGT"} :backward {:pos 4, :ref "C", :alt "CAGTCTT"}
-      {:pos 13, :ref "TCTTAGT", :alt "T"} :backward {:pos 4, :ref "CAGTCTT", :alt "C"})))
+      {:pos 13, :ref "TCTTAGT", :alt "T"} :backward {:pos 4, :ref "CAGTCTT", :alt "C"}))
+  (testing "protein sequence"
+    (are [v d ret] (= (common/apply-3'-rule v "MDDLWFTFTPGPDE" d) ret)
+      {:pos 5 :ref "WFT" :alt "W"} :forward {:pos 7 :ref "TFT" :alt "T"}
+      {:pos 5 :ref "WFT" :alt "F"} :forward {:pos 5 :ref "WFT" :alt "F"}
+      {:pos 5 :ref "WFT" :alt "T"} :forward {:pos 5 :ref "WFT" :alt "T"})))
 
 (defslowtest normalize-variant-test
   (cavia-testing "normalize without error"
diff --git a/test/varity/vcf_to_hgvs/protein_test.clj b/test/varity/vcf_to_hgvs/protein_test.clj
index ed0afc5..85de624 100644
--- a/test/varity/vcf_to_hgvs/protein_test.clj
+++ b/test/varity/vcf_to_hgvs/protein_test.clj
@@ -1,7 +1,11 @@
 (ns varity.vcf-to-hgvs.protein-test
   (:require [clojure.string :as string]
             [clojure.test :refer :all]
-            [varity.vcf-to-hgvs.protein :as prot]))
+            [cljam.io.sequence :as cseq]
+            [clj-hgvs.core :as hgvs]
+            [varity.vcf-to-hgvs.protein :as prot]
+            [varity.t-common :refer [test-ref-seq-file
+                                     defslowtest]]))
 
 (deftest alt-exon-ranges-test
   ;; 1 [2 3 4] 5 6 7 [8 9 10 11] 12 13 14 15
@@ -95,3 +99,23 @@
                            "YDIGGPDQEFGVDVGPVCFL*"
                            "YDIGGPDQEFGVDVGPVCFLQ"
                            "                    ^"])))
+
+(defslowtest protein-seq-3'-rule-test
+  (let [tp53 {:name2 "TP53"
+              :name "NM_000546.6"
+              :chr "chr17"
+              :tx-start 7668421
+              :tx-end 7687490
+              :cds-start 7669609
+              :cds-end 7676594
+              :strand :reverse
+              :cds-start-stat :cmpl
+              :cds-end-stat :cmpl
+              :exon-ranges [[7668421 7669690] [7670609 7670715] [7673535 7673608] [7673701 7673837] [7674181 7674290] [7674859 7674971] [7675053 7675236] [7675994 7676272] [7676382 7676403] [7676521 7676622] [7687377 7687490]]
+              :bin 643
+              :exon-frames [2 0 1 2 0 1 0 0 2 0 -1]
+              :exon-count 11}]
+    (are [pos ref alt res]
+        (= (with-open [seq-rdr (cseq/reader test-ref-seq-file)] (#'prot/mutation seq-rdr tp53 pos ref alt {})) res)
+      7676197 "G" "GGTCTTGTCCCTTA" (:mutation (hgvs/parse "p.P58*"))
+      7676202 "T" "TGTCCCTTAGTCTT" (:mutation (hgvs/parse "p.P58*")))))
diff --git a/test/varity/vcf_to_hgvs_test.clj b/test/varity/vcf_to_hgvs_test.clj
index 91f0028..70d6488 100644
--- a/test/varity/vcf_to_hgvs_test.clj
+++ b/test/varity/vcf_to_hgvs_test.clj
@@ -72,6 +72,21 @@
                                            "NM_001176:c.-147_-138delTCTCTGCCGG"
                                            "NM_006849:c.-2636_-2627delTCTCTGCCGG") ; cf. rs1460727826 (deletion in UTR)
         "chr6" 33086236 "TA" "T" '("NM_002121:c.776delA") ; cf. rs67523850 (deletion in border of UTR)
+        "chr17" 7675170 "CAA" "C" '("NM_001126115:c.44_45delTT"
+                                    "NM_001126116:c.44_45delTT"
+                                    "NM_001126117:c.44_45delTT"
+                                    "NM_001276697:c.-38_-37delTT"
+                                    "NM_001276698:c.-38_-37delTT"
+                                    "NM_001276699:c.-38_-37delTT"
+                                    "NM_000546:c.440_441delTT"
+                                    "NM_001126112:c.440_441delTT"
+                                    "NM_001126113:c.440_441delTT"
+                                    "NM_001126114:c.440_441delTT"
+                                    "NM_001126118:c.323_324delTT"
+                                    "NM_001276695:c.323_324delTT"
+                                    "NM_001276696:c.323_324delTT"
+                                    "NM_001276760:c.323_324delTT"
+                                    "NM_001276761:c.323_324delTT")
 
         ;; Duplication
         "chr2" 47806844 "T" "TGATT" '("NM_000179:c.4068_4071dupGATT"
@@ -190,6 +205,7 @@
         "chr1" 247815239 "AAGG" "A" '("p.S163del") ; cf. rs35979231 (-)
         "chr2" 29223408 "AAGCAGT" "A" '("p.Y1096_C1097del") ; cf. rs776101205 (-)
         "chr11" 108259071 "GT" "G" '("p.L822*") ; https://github.com/chrovis/varity/issues/49
+        "chr17" 7676206 "TGAACCATTGTTCAATATCGTCCGGGGACAGCATCAAATCATCCATTGCTTGGGACGGCAAGGGG" "T" '("p.P34Lfs*68" "p.M1ext-78" "p.M1ext-39") ; https://mutalyzer.nl/normalizer/NC_000017.11:g.7676209_7676272del
 
         ;; Duplication
         "chr2" 26254257 "G" "GACT" '("p.T2dup") ; cf. rs3839049 (+)