MedGen

Nonphotosensitive trichothiodystrophy-8 (TTD8) is characterized by brittle hair and nails and scaly skin, accompanied by failure to thrive, microcephaly, and neuromotor developmental delay. Hair analysis shows low sulfur content, and skin fibroblasts demonstrate normal DNA repair efficiency after UV irradiation (Botta et al., 2021). For a general phenotypic description and discussion of genetic heterogeneity of trichothiodystrophy, see TTD1 (601675). [from OMIM]

Hereditary diffuse leukoencephalopathy with spheroids-2 (HDLS2) is an autosomal dominant neurodegenerative disorder characterized by progressive cognitive and executive dysfunction, psychiatric disturbances, and neurologic symptoms, such as gait abnormalities, paresis, seizures, and rigidity. Symptom onset is usually in adulthood, although earlier onset has been reported. Some patients have an acute encephalopathic course with severe neurologic decline resulting in early death, whereas other patients have a more protracted and chronic disease course. Neuropathologic examination shows a leukoencephalopathy with axonal spheroids and myelination defects (summary by Sundal et al., 2012). For a discussion of genetic heterogeneity of HDLS, see HDLS1 (221820). [from OMIM]

Developmental and epileptic encephalopathy-29 (DEE29) is an autosomal recessive neurologic disorder characterized by the onset of refractory myoclonic seizures in the first months of life. Affected individuals have poor overall growth, congenital microcephaly with cerebral atrophy and impaired myelination on brain imaging, spasticity with abnormal movements, peripheral neuropathy, and poor visual fixation (summary by Simons et al., 2015). For a general phenotypic description and a discussion of genetic heterogeneity of DEE, see 308350. [from OMIM]

A mild form of axonal Charcot-Marie-Tooth disease, a peripheral sensorimotor neuropathy, with characteristics of distal legs sensory loss and weakness that can be asymmetric. Tendon reflexes are reduced in the knees and absent in ankles. Progression is slow. [from SNOMEDCT_US]