diff --git a/src/components/VariantSampleTable.tsx b/src/components/VariantSampleTable.tsx
index 6fda8d5f..cecc56fa 100644
--- a/src/components/VariantSampleTable.tsx
+++ b/src/components/VariantSampleTable.tsx
@@ -42,7 +42,7 @@ export const VariantSampleTable: Component<{
                           allelicBalance={
                             props.record.data.s[props.samples[i()].index]["VIAB"] as number | undefined | null
                           }
-                          readDepth={props.record.data.s[props.samples[i()].index]["DP"] as number | undefined}
+                          readDepth={props.record.data.s[props.samples[i()].index]["DP"] as number | undefined | null}
                         />
                       </td>
                     )}
diff --git a/src/components/record/Format.tsx b/src/components/record/Format.tsx
index 0cac4493..ace5be23 100644
--- a/src/components/record/Format.tsx
+++ b/src/components/record/Format.tsx
@@ -13,7 +13,7 @@ export const Format: Component<{
   record: Item<Record>;
   isAbbreviate: boolean;
   allelicBalance: number | undefined | null;
-  readDepth: number | undefined;
+  readDepth: number | undefined | null;
 }> = (props) => {
   return (
     <Switch
diff --git a/src/components/record/format/GenotypeField.tsx b/src/components/record/format/GenotypeField.tsx
index d165ef42..2509bcd3 100644
--- a/src/components/record/format/GenotypeField.tsx
+++ b/src/components/record/format/GenotypeField.tsx
@@ -35,10 +35,10 @@ export const GenotypeField: Component<{
   altAlleles: (string | null)[];
   isAbbreviate: boolean;
   allelicBalance: number | undefined | null;
-  readDepth: number | undefined;
+  readDepth: number | undefined | null;
 }> = (props) => {
   const allelicImbalance: boolean = isAllelicImbalance(props.genotype, props.allelicBalance);
-  const lowReadDepth = props.readDepth !== undefined && props.readDepth < 20;
+  const lowReadDepth = props.readDepth !== undefined && props.readDepth !== null && props.readDepth < 20;
   return (
     <>
       <For each={props.genotype.a}>