The Mocs2A subunit mutation, a C to T change at position 88 (c.88C>T) resulting in a glutamine to a termination codon at amino acid 30 (p.Q30*) was introduced in exon 3. In addition, a loxP-flanked neomycin cassette was inserted downstream of exon 3. This is a variant found in patients with molybdenum cofactor deficiency type B. (J:336726)