Congenital nasolacrimal drainage system impatency is relatively common, occurring in approximately 20% of children within the first year of life. Such infants typically manifest persistent epiphora and/or recurrent infections of the lacrimal pathway such as conjunctivitis. The most frequent site of such obstruction occurs at the distal intranasal segment of the nasolacrimal drainage system at the valve of Hasner (summary by Wang and Cunningham, 2011). Congenital dacryocystocele, an uncommon variant of nasolacrimal duct obstruction, characterized by the appearance of a cystic blue mass over the area of the lacrimal duct soon after birth. Dacryocystoceles are thought to result from a persistent membrane at the valve of Hasner and a functional obstruction of the common canaliculus or valve of Rosenmuller. The resulting lacrimal sac distention has been reported to be more common in female and non-Hispanic white patients, and familial cases have been described only sporadically. Common presenting signs include dacryocystitis, facial cellulitis, and respiratory distress; the development of astigmatism in association with dacryocystocele has only rarely been observed (summary by Shekunov et al., 2010).

Atelis syndrome-2 (ATELS2) is an autosomal recessive disorder characterized by poor overall growth with microcephaly and short stature, dysmorphic facial features, and congenital cardiac defects. Additional more variable features may include hematologic abnormalities, variable ocular abnormalities, motor delay, and anxiety. Patient cells exhibit a unique chromosomal instability phenotype consisting of segmented and dicentric chromosomes with mosaic variegated hyperploidy (Grange et al., 2022). See also ATELS1 (620184), caused by mutation in the SLF2 gene (610348). For a discussion of genetic heterogeneity of MVA, see MVA1 (257300).