Identification of Oliver-McFarlane syndrome caused by novel compound heterozygous variants of PNPLA6.

OBJECTIVES

Oliver-McFarlane syndrome (OMCS) is an autosomal recessive inherited disease resulting from PNPLA6 mutations that results in intellectual impairment and profound short stature. To obtain a better understanding of the genotype-phenotype correlations for PNPLA6-related disorders, we reported the 14th OMCS case and summarized all the reported cases of OMCS.

METHODS

We collected clinical biochemical and data and brain MRI data and used whole-exon gene detection and analysis tools to evaluate the pathogenicity of the variants, including PolyPhen-2 and Mutation Taster, and we also generated three-dimensional protein structures and visualized the effects of altered residues with I-TASSER and PyMOL Viewer software.

RESULTS

The patient presented with trichomegaly and multiple pituitary hormone deficiencies. Brain MRI showed small pituitary and bilateral paraventricular leukomalacia. Novel variants (c.1491G > T and c.3367G > A) in the PNPLA6 gene were detected in the proband and verified by direct sequencing. Amino acid residues of Gln497 and Gly1123 are predicted to be damaging and destroy the three-dimensional protein structures of the protein. In follow-up, this patient could neither walk nor hold his head erect and had not spoken one word at the age of one year and ten months. Moreover, there is no obvious hot spot mutation in any of the reported allelic variants. Interestingly, the majority of mutations are located in the phospholipid esterase domain, which is responsible for esterase activity.

CONCLUSIONS

We identified two novel variants of the PNPLA6 gene in an OMCS patient, which will help to better understand the function of PNPLA6 and genotype-phenotype correlations for PNPLA6-related disorders.