Folbigg gene a 'bad variant', inquiry told

Professors Mette Nyegaard and Michael Toft Overgaard appeared at the second Folbigg inquiry. (Bianca De Marchi/AAP PHOTOS) (AAP)

Two genetic experts have told the inquiry into the convictions of Kathleen Folbigg a "bad variant" likely led to the deaths of her two daughters.

However, the variant does not explain the deaths of her two sons, the inquiry heard.