The concept of Dejerine-Sottas disease, which corresponds to presumed recessive demyelinating neuropathies with onset in infancy, remains controversial. To learn more on the subject, we performed a clinico-pathological and molecular genetic study in 15 unrelated patients with the Dejerine-Sottas phenotype seen over a 16 year period. There were 12 females and 3 males, born to asymptomatic parents. Study of the PMP22, P-0 and Egr2 genes was performed in all cases and 14 underwent a nerve biopsy. First manifestations of neuropathy occurred before 3 years of age in all patients. An inherited disorder was suspected in 10 patients, because of their family history and/or disclosure of a molecular genetic defect in 4 of them. One patient had a recessively transmitted homozygous point mutation (Arg157Trp) of the PMP22 gene. A heterozygous duplication of the 17p11.2-12 segment was detected in one offspring of a consanguineous marriage. One patient carried a "de novo" heterozygous Ser72Leu substitution in the PMP22. A heterozygous double mutation of the Po gene including a "de novo"Val42 deletion and an Ala221 Thr substitution, maternally inherited, were found in an apparently sporadic case. No mutation of the Egr2 gene was identified. A neuropathy with focally folded myelin sheaths (CMT4B) was diagnosed in the nerve biopsy specimens of two patients. In five patients, the clinico-pathological findings along with the absence of an identified mutation suggested the diagnosis of chronic inflammatory demyelinating polyneuropathy of infantile onset. Our findings illustrate the genetic heterogeneity of cases with identified mutations, the scarcity of cases with "demonstrated" recessive transmission and the likelihood of early acquired chronic inflammatory demyelinating polyneuropathy in several patients.