They mention the allele α-LEPRA as also implicated in hereditary spherocytosis, a C>T substitution at position -99 of intron 30. They say this is linked in cis to the α-IIs (A970D) substitution. The α-LEPRA variant appears to be implicated as the causal variant.
Edited in this revision:
Mentions finding of the A970D variant and concludes it is in linkage disequilibrium with another causal variant.
This paper mentions A970D as a functionally neutral allele that is associated with α-LEPRA: “PCR screening of mutation αLEPRA and a functionally neutral mutation, Bughill (C→A, at position 11 of exon 21; GCT→GAT: A970D), which is inconstantly carried by allele αLEPRA”.
This variant is noted to be linked to alpha-LEPRA and is seen frequently in individuals with recessive Hereditary pyropoikilocytosis.