MedGen

Any autosomal recessive nonsyndromic deafness in which the cause of the disease is a mutation in the SERPINB6 gene. [from MONDO]

Developmental and epileptic encephalopathy-91 (DEE91) is characterized by delayed psychomotor development apparent in infancy and resulting in severely to profoundly impaired intellectual development with poor or absent speech. Most patients never achieve independent walking. Patients typically have onset of refractory multifocal seizures between the first weeks and years of life, and some may show developmental regression. Additional features, such as hypotonia and cortical visual impairment, are more variable (summary by Myers et al., 2017). For a discussion of genetic heterogeneity of DEE, see 308350. [from OMIM]

Any non-syndromic X-linked intellectual disability in which the cause of the disease is a mutation in the ZDHHC15 gene. [from MONDO]

Spermatogenic failure-91 (SPGF91) is characterized by male infertility due to teratozoospermia. Patient sperm show defects of the head, including a misshapen rounded head and detachment of the acrosome, and the sperm fail to attach to the zona pellucida of the egg. Pregnancy can be achieved using intracytoplasmic sperm injection (ICSI) (Oud et al., 2020; Fan et al., 2022). For a general phenotypic description and discussion of genetic heterogeneity of spermatogenic failure, see SPGF1 (258150). [from OMIM]

Immunodeficiency-91 and hyperinflammation (IMD91) is an autosomal recessive complex immunologic disorder characterized by both immunodeficiency and recurrent infections, often to viruses or mycobacteria, as well as by hyperinflammation with systemic involvement. Affected individuals present in infancy with variable features, including fever, infection, thrombocytopenia, renal or hepatic dysfunction, recurrent infections, or seizures. Most patients eventually develop hepatic or renal failure, compromised neurologic function, lymphadenopathy or hepatosplenomegaly, and multiorgan failure resulting in death. More variable features may include intermittent monocytosis, features of hemophagocytic lymphohistiocytosis (HLH), and serologic evidence of hyperinflammation. The disorder is thought to result from dysregulation of the interferon response to viral stimulation in the innate immune system (summary by Le Voyer et al., 2021; Vavassori et al., 2021). [from OMIM]

Autosomal dominant spastic paraplegia-91 with or without cerebellar ataxia (SPG91) is a highly variable neurologic disorder characterized by early-onset gait abnormalities due to spastic paraplegia of the lower limbs, sometimes with cerebellar ataxia. The age at onset is highly variable (congenital to young adult), although most patients have symptom onset in the first decade. Some patients present with a spastic paraplegia-predominant phenotype with significant pyramidal signs, whereas others present with an ataxic-predominant phenotype. In addition, although most patients have a more 'pure' phenotype restricted to gait abnormalities without additional features, others have a more 'complicated' phenotype with additional features such as sensory abnormalities, peripheral neuropathy, optic neuropathy, developmental delay, variably impaired intellectual development, and seizures. Many have normal brain imaging, but cerebellar atrophy may be observed in those with prominent cerebellar ataxia (Van de Vondel et al., 2022). For a general phenotypic description and a discussion of genetic heterogeneity of autosomal dominant spastic paraplegia, see SPG3A (182600). [from OMIM]

Osteogenesis imperfecta type XVI (OI16) is characterized by prenatal onset of multiple fractures of ribs and long bones, blue sclerae, decreased ossification of the skull, and severe demineralization. Heterozygous family members may exhibit recurrent fractures with minimal trauma, osteopenia, and blue sclerae (Keller et al., 2018; Lindahl et al., 2018). [from OMIM]

Retinitis pigmentosa-91 (R91) is characterized by night blindness and constriction of visual fields, with bone-spicule pigmentation, attenuation of retinal vessels, and optic disc pallor on funduscopy. Patients may also experience early macular involvement, with photophobia and reduced visual acuity, and some show a bull's eye pattern of macular atrophy (Olivier et al., 2021). [from OMIM]