Dyskeratosis Congenita, Autosomal Recessive 2

A number sign (#) is used with this entry because autosomal recessive dyskeratosis congenita-2 (DKCB2) is caused by homozygous or compound heterozygous mutation in the NOLA2 gene (606470), also known as NHP2, on chromosome 5q35.

Description

Dyskeratosis congenita is a multisystem disorder caused by defective telomere maintenance. Clinical manifestations include mucocutaneous abnormalities, bone marrow failure, and an increased predisposition to cancer, among other variable features (summary by Vulliamy et al., 2008).

For a discussion of genetic heterogeneity of dyskeratosis congenita, see DKCA1 (127550).

Clinical Features

Vulliamy et al. (2008) reported a Turkish man with nail dystrophy, thrombocytopenia, testicular atrophy, opportunistic infections, growth and mental retardation, liver cirrhosis, and intracranial calcification. His parents were asymptomatic and unrelated. Another unrelated Turkish boy presented with dyskeratosis congenita at age 12 years. He had the classic mucocutaneous triad of nail dystrophy, leukoplakia, and reticulate skin pigmentation and developed peripheral pancytopenia due to progressive bone marrow failure. No other somatic abnormalities were reported. His parents were asymptomatic. Both patients had shortened telomeres and decreased levels of serum TERC (602322) RNA.

Molecular Genetics

In 2 unrelated Turkish patients with autosomal recessive dyskeratosis congenita, Vulliamy et al. (2008) identified biallelic mutations in the NOLA2 gene (606470.0001-606470.0003). The 2 patients were identified from a larger group of 117 patients with the disorder; no other pathogenic NOLA2 variants and no mutations in the GAR1 gene (606468) were identified.