diff --git a/app/models/Backend.scala b/app/models/Backend.scala
index bab21f64..322a18fc 100644
--- a/app/models/Backend.scala
+++ b/app/models/Backend.scala
@@ -251,14 +251,14 @@ class Backend @Inject() (implicit
     retriever.map {
       case (Seq(), _, _) => None
       case (credset, _, _) =>
-        val loci = credset.flatMap(cs => (cs \ "locus").as[Seq[Locus]])
+        val loci = credset.flatMap(cs => (cs \ "locus").asOpt[Seq[Locus]].getOrElse(Seq()))
         logger.info(s"loci: $loci")
         val count = loci.size
         val filteredLoci = variantIds match {
           case Some(variantIds) => loci.filter(l => variantIds.contains(l.variantId.getOrElse("")))
           case None             => loci
         }
-        Some(Loci(count, filteredLoci.take(sizeLimit.getOrElse(Pagination.sizeDefault))))
+        Some(Loci(count, Some(filteredLoci.take(sizeLimit.getOrElse(Pagination.sizeDefault)))))
     }
   }
 
diff --git a/app/models/entities/CredibleSet.scala b/app/models/entities/CredibleSet.scala
index 996387c2..529031ed 100644
--- a/app/models/entities/CredibleSet.scala
+++ b/app/models/entities/CredibleSet.scala
@@ -44,7 +44,7 @@ case class Locus(
 
 case class Loci(
     count: Long,
-    rows: Seq[Locus]
+    rows: Option[Seq[Locus]]
 )
 
 case class LdSet(
@@ -116,7 +116,7 @@ object CredibleSet extends Logging {
 
   implicit val lociR: Reads[Loci] = (
     (JsPath \ "count").read[Long] and
-      (JsPath \ "locus").read[Seq[Locus]]
+      (JsPath \ "locus").readNullable[Seq[Locus]]
   )(Loci.apply _)
 
   val credibleSetFields: Seq[Field[Backend, JsValue]] = Seq(