Two siblings with PEX11B-related peroxisome biogenesis disorder

Abstract

The PEX11β gene contains four exons and encodes peroxisomal membrane protein 11β, which is involved in peroxisome proliferation and division. Pathogenic variants in this gene result in a rare genetic disorder with autosomal recessive inheritance called peroxisome biogenesis disorder 14B (MIM: 614920). Here, we report two affected siblings with a novel variant (NM_003846: c.11G > A, p. Trp4Ter) in the PEX11β gene that was identified by whole exome sequencing and confirmed by Sanger sequencing. The proband is a 22-year-old Iranian female who was born to consanguineous parents. The homozygous variant (NM_003846: c.11G > A, p. Trp4Ter) in the PEX11β gene was identified in the proband, who presented with cataracts, strabismus, nystagmus, intellectual disability, developmental delay, speech disorders, dry skin, and behavioral problems. Her younger affected brother, who had the same homozygous variant, suffered from similar but slightly milder symptoms. This paper reports the seventh family in the world with novel pathogenic variants in the PEX11β gene as the cause of peroxisome biogenesis disorder 14B. Additionally, the phenotypes of the previously reported patients are reviewed. Some of the phenotypes, such as bilateral congenital cataracts and intellectual disability, were present in all patients. However, other observed symptoms in previous cases, such as abnormal gait, myopia, abnormal muscle strength, hearing loss, gastrointestinal problems, skeletal disorders, and seizures, were not observed in the patients of this study. Further studies on this disorder could be valuable in determining the precise phenotype characteristics of this disease.

Keywords: Behavioral problems; Congenital cataract; Intellectual disability; Neurologic abnormalities; PBD14B; Peroxisomal diseases.