Peutz–Jeghers syndrome (PJS) is a rare autosomal dominant inherited disorder characterized by gastrointestinal (GI) hamartomatous polyps, mucocutaneous hyperpigmentation, and an increased risk of cancer. Mutations in the serine–threonine kinase 11 gene (SKT11) are the major cause of PJS. Blood samples were collected from six PJS families including eight patients. Mutation screening of STK11 gene was performed in these six families by Sanger sequencing and multiplex ligation-dependent probe amplification (MLPA) assay. Three novel mutations (c.721G > C, c.645_726del82, and del(exon2–5)) and three recurrent mutations (c.752G > A, c.545 T > C and del(exon1)) in STK11 were detected in six Chinese PJS families. Genotype-phenotype correlations suggested that truncating mutations trend to result in severe complications. These findings broaden the mutation spectrum of the STK11 gene and would help clinicians and genetic counselors provide better clinical surveillance for PJS patients, especially for ones carrying truncating mutation.

Increasing number of cases with small supernumerary marker chromosomes (sSMCs) without centromeric DNA and dozens of cases with trisomy 2q3 have been reported in recent years. However, cases of simultaneous sSMC and partial trisomy of chromosome 2q have been rarely described. We report the case of a young girl patient with growth retardation and mild facial features due to a partial trisomy 2q33.3-37.3. The 34.3 Mb-duplication of the 2q33.3 to q37.3 region found in the patient constituted a supernumerary inverted duplicated neocentric marker chromosome. This is the first case of a patient with partial trisomy 2q33.3-37.3 presenting an inverted duplicated neocentric marker chromosome. Based on the case, this study will help further understanding the genotype/phenotype correlations of partial 2q3 duplication and exploring the relationship between neocentric sSMC and human diseases.