MedGen

Any retinitis pigmentosa in which the cause of the disease is a mutation in the RBP3 gene. [from MONDO]

Any autosomal recessive nonsyndromic deafness in which the cause of the disease is a mutation in the DCDC2 gene. [from MONDO]

Developmental and epileptic encephalopathy-66 (DEE66) is a neurologic disorder characterized by the onset of various types of seizures in the first days or weeks of life. Most seizures have focal origins; secondary generalization is common. Seizure control is difficult at first, but may become easier with time. Affected individuals show global developmental delay with hypotonia, behavioral abnormalities, and dysmorphic features or ophthalmologic defects. Brain imaging often shows cerebellar dysgenesis. A subset of patients have extraneurologic manifestations, including hematologic and distal limb abnormalities (summary by Olson et al., 2018). For a general phenotypic description and a discussion of genetic heterogeneity of DEE, see 308350. [from OMIM]

Autosomal dominant deafness-66 is a form of nonsyndromic sensorineural hearing impairment with widely variable age at onset (Nyegaard et al., 2015). [from OMIM]

MRT66 is a nonsyndromic autosomal recessive intellectual developmental disorder with delayed speech development, neuropsychiatric symptoms, and relatively normal life span (Philips et al., 2017). [from OMIM]

Immunodeficiency-66 (IMD66) is an autosomal recessive primary immune disorder caused by defective immune cell migration and chemotaxis resulting from defects in cytoskeletal actin dynamics. Neutrophils are primarily affected, although there may be defects in dendritic cells and T and B cells. The phenotype is characterized by onset of recurrent bacterial infections in infancy. Laboratory studies show normal levels of myeloid and lymphoid cells, but there may be mild thrombocytopenia (summary by Record et al., 2015). [from OMIM]

Autosomal recessive spastic paraplegia type 66 is a rare, complex hereditary spastic paraplegia disorder with characteristics of infantile onset of progressive lower limb spasticity, severe gait disturbances leading to a non-ambulatory state, absent deep tendon reflexes and amyotrophy. Additional signs include severe sensorimotor neuropathy, pes equinovarus and mild intellectual disability. Cerebellar and corpus callosum hypoplasia, as well as colpocephaly, are observed on neuroimaging. [from SNOMEDCT_US]

Spermatogenic failure-66 (SPGF66) is characterized by male infertility due to all sperm being round-headed (globozoospermia) and lacking the acrosome (Oud et al., 2020). For a general phenotypic description and discussion of genetic heterogeneity of spermatogenic failure, see SPGF1 (258150). [from OMIM]

Autosomal dominant intellectual developmental disorder-66 (MRD66) is characterized by global developmental delay with mildly to moderately impaired intellectual development and mild speech delay. The phenotype and severity are highly variable. Some patients have behavioral problems or autism spectrum disorder, and about 50% have variable types of seizures. Additional features may include nonspecific dysmorphic facial features, tall or short stature, and mild skeletal anomalies (Rahimi et al., 2022). [from OMIM]

A precursor lymphoid neoplasm composed of B-lymphoblasts which contain more than 50 and usually less than 66 chromosomes. It has a favorable clinical outcome. [from NCI]