Let G be a finite group. Moghaddamfar et al. defined prime graph Γ(G) of group G as follows. The vertices of Γ(G) are the primes dividing the order of G and two distinct vertices p, q are joined by an edge, denoted by p ∼ q , if there is an element in G of order pq . AssumeDenote by π(G) the set of prime divisor of |G| . Let GK(G) be the graph with vertex set π(G) such that two primes p and q in π(G) are joined by an edge if G has an element of order p • q . We set s(G) to denote the number of connected components of the prime graph GK(G) . Some authors proved some groups are OD -characterizable with s(G) ≥ 2 .Then for s(G) = 1 , what is the influence of OD on the structure of groups? We knew that the alternating groups Ap+3 , where 7 ̸ = p ∈ π(100!) , A130 and A140 are OD -characterizable. Therefore, we naturally ask the following question: if s(G) = 1 , then is there a group OD -characterizable? In this note, we give a characterization of Ap+3 except A10 with s(Ap+3) = 1 , by OD , which gives a positive answer to Moghaddamfar and Rahbariyan's conjecture.