A homozygous NOP14 variant is likely to cause recurrent pregnancy loss.

Recurrent pregnancy loss is newly defined as more than two consecutive miscarriages. Recurrent pregnancy loss occurs in <5% of total pregnancies. The cause in approximately 40-60% of recurrent pregnancy loss cases remains elusive and must be determined. We investigated two unrelated Iranian consanguineous families with recurrent pregnancy loss. We performed exome sequencing using DNA from a miscarriage tissue and identified a homozygous NOP14 missense variant (c.[136C>G];[136C>G]) in both families. NOP14 is an evolutionally conserved protein among eukaryotes and is required for 18S rRNA processing and 40S ribosome biogenesis. Interestingly, in zebrafish, homozygous mutation of nop14 (possibly loss of function) resulting from retrovirus-mediated insertional mutagenesis led to embryonic lethality at 5 days after fertilization, mimicking early pregnancy loss in humans. Similarly, it is known that the nop14-null yeast is inviable. These data suggest that the homozygous NOP14 mutation is likely to cause recurrent pregnancy loss. Furthermore, this study shows that exome sequencing is very useful to determine the etiology of unsolved recurrent pregnancy loss.

A novel homozygous mutation in HSF4 causing autosomal recessive congenital cataract.

Cataract is defined as opacity in the crystalline lens and congenital cataract occurs during the first year of life. Until now, mutations of more than 50 genes in congenital cataract have been reported with various modes of inheritance. Among them, HSF4 mutations have been reported in autosomal dominant, autosomal recessive and age-related forms of cataract. The inheritance patterns of these mutations depend on their mutational positions in HSF4: autosomal dominant or recessive mutations are respectively found either in a DNA-binding domain or in (or downstream of) hydrophobic repeats. Here we report a novel homozygous HSF4 mutation (c.521T>C, p.Leu174Pro) in two affected sibs of an Iranian consanguineous family using whole exome sequencing. The mutation is predicted as highly pathogenic by in silico analysis (SIFT, Polyphen2 and MutationTaster) and is not found in any of control databases. This mutation is located in a hydrophobic repeat of the HSF4 protein, which is consistent with the mode of inheritance as an autosomal recessive trait.