MedGen

Any autosomal recessive nonsyndromic deafness in which the cause of the disease is a mutation in the LOXHD1 gene. [from MONDO]

The spectrum of FARS2 deficiency ranges from the infantile-onset phenotype, characterized by epileptic encephalopathy with lactic acidosis and poor prognosis (70% of affected individuals), to the later-onset phenotype, characterized by spastic paraplegia, less severe neurologic manifestations, and longer survival (30% of affected individuals). To date FARS2 deficiency has been reported in 37 individuals from 25 families. Infantile-onset phenotype. Seizures are difficult to control and may progress quickly at an early age to intractable seizures with frequent status epilepticus; some children have hypsarrhythmia on EEG. All have developmental delay; most are nonverbal and unable to walk. Feeding difficulties are common. More than half of affected children die in early childhood. Later-onset phenotype. All affected individuals have spastic paraplegia manifested by weakness, spasticity, and exaggerated reflexes of the lower extremities associated with walking difficulties; some have developmental delay/intellectual disability; some have brief seizures that resolve over time. [from GeneReviews]

PAX2-related disorder is an autosomal dominant disorder associated with renal and eye abnormalities. The disorder was originally referred to as renal coloboma syndrome and characterized by renal hypodysplasia and abnormalities of the optic nerve; with improved access to molecular testing, a wider range of phenotypes has been recognized in association with pathogenic variants in PAX2. Abnormal renal structure or function is noted in 92% of affected individuals and ophthalmologic abnormalities in 77% of affected individuals. Renal abnormalities can be clinically silent in rare individuals. In most individuals, clinically significant renal insufficiency / renal failure is reported. End-stage renal disease requiring renal transplant is not uncommon. Uric acid nephrolithiasis has been reported. Ophthalmologic abnormalities are typically described as optic nerve coloboma or dysplasia. Iris colobomas have not been reported in any individual with PAX2–related disorder. Ophthalmologic abnormalities may significantly impair vision in some individuals, while others have subtle changes only noted after detailed ophthalmologic examination. Additional clinical findings include high-frequency sensorineural hearing loss, soft skin, and ligamentous laxity. PAX2 pathogenic variants have been identified in multiple sporadic and familial cases of nonsyndromic renal disease including renal hypodysplasia and focal segmental glomerulosclerosis. [from GeneReviews]

Multiple congenital anomalies-hypotonia-seizures syndrome-4 (MCAHS4) is an autosomal recessive neurologic disorder characterized by onset of refractory seizures in the first months of life. Patients have severe global developmental delay, and may have additional variable features, including dysmorphic or coarse facial features, visual defects, and mild skeletal or renal anomalies. At the cellular level, the disorder is caused by a defect in the synthesis of glycosylphosphatidylinositol (GPI), and thus affects the expression of GPI-anchored proteins at the cell surface (summary by Starr et al., 2019). For a discussion of genetic heterogeneity of MCAHS, see MCAHS1 (614080). For a discussion of genetic heterogeneity of DEE, see 308350. For a discussion of genetic heterogeneity of GPI biosynthesis defects, see GPIBD1 (610293). [from OMIM]

Any retinitis pigmentosa in which the cause of the disease is a mutation in the REEP6 gene. [from MONDO]

Autosomal recessive intellectual developmental disorder-77 (MRT77) is a nonsyndromic neurodevelopmental disorder characterized by global developmental delay with variably impaired cognitive development apparent from infancy. Affected individuals usually have delayed walking, sometimes with an unsteady gait, and may have poor speech and communication. Brain imaging is normal, and there are no additional significant neurologic abnormalities (Khoshbakht et al., 2021). Mutation in the CEP104 gene also causes a form of Joubert syndrome (JBTS25; 616781). [from OMIM]

Immunodeficiency-77 (IMD77) is an immunologic disorder characterized by recurrent and persistent polymicrobial infections with multiple unusual organisms. Skin and pulmonary infections are the most common, consistent with increased susceptibility to epithelial cell infections. The age at onset is highly variable: some patients have recurrent infections from childhood, whereas others present in late adulthood. The limited number of reported patients are all female, suggesting incomplete penetrance or a possible sex-influenced trait. Patient cells, mainly macrophages, show impaired killing of intracellular bacteria and organisms, including nontubercular mycobacteria, although there is also impaired killing of other organisms, such as Pseudomonas, Candida, and Aspergillus. Treatment with gamma-IFN (IFNG; 147570) may be a therapeutic option (summary by McCormack et al., 2017 and Merselis et al., 2020). [from OMIM]

Spermatogenic failure-77 (SPGF77) is characterized by male infertility due to extreme oligozoospermia or azoospermia. Nearly all spermatozoa present on semen analysis are morphologically abnormal, with amorphous, enlarged, and/or fragmented heads, and some are multiflagellated. Testicular tissue shows arrest at the round spermatid stage (Wyrwoll et al., 2022). For a general phenotypic description and a discussion of genetic heterogeneity of spermatogenic failure, see SPGF1 (258150). [from OMIM]

Autosomal dominant deafness-77 (DFNA77) is characterized by progressive hearing loss affecting high frequencies beginning in the second to third decades of life and affecting all frequencies by the fourth or fifth decades (Li et al., 2019). [from OMIM]

Dworschak-Punetha neurodevelopmental syndrome (DWOPNED) is an autosomal recessive disorder characterized mainly by global developmental delay and mildly impaired intellectual development (IQ range 77 to 85), often with behavioral abnormalities, including autism spectrum disorder and hyperactivity. Some affected individuals may have only speech delay or behavioral manifestations. More variable additional features include optic disc hypoplasia, ptosis, hypo- or hyperpigmented skin lesions, nonspecific dysmorphic facial features, and brain imaging abnormalities of the ventricles or corpus callosum. Of note, not all patients exhibit all features, and there is significant inter- and intrafamilial phenotypic variability (Dworschak et al., 2021). [from OMIM]