A rare autosomal recessive inherited syndrome. It is characterized by xeroderma pigmentosum, mental retardation, dwarfism, hypogonadism, and neurologic abnormalities.

The dyssegmental dysplasias are lethal forms of neonatal short-limbed dwarfism. Handmaker et al. (1977) coined the term 'dyssegmental dysplasia' because of the marked differences in size and shape of the vertebral bodies (anisospondyly), which he attributed to errors in segmentation. Fasanelli et al. (1985) proposed that there are different forms of dyssegmental dwarfism, a lethal Silverman-Handmaker type (224410) and a less severe Rolland-Desbuquois type. The Rolland-Desbuquois form is lethal in about 40% of patients. Although many patients survive beyond the newborn period, all exhibit neonatal distress (summary by Hennekam et al., 2010).

Distal arthrogryposis type 4 (DA4) is distinguished by the presence of scoliosis (summary by Bamshad et al., 2009). For a phenotypic description and a discussion of genetic heterogeneity of distal arthrogryposis, see DA1 (108120).

Mitochondrial axonal Charcot-Marie-Tooth disease (CMTMA) is inherited only through the maternal line. The disorder is characterized by onset of distal muscle weakness and atrophy mainly affecting the lower limbs and resulting in difficulty walking in the second decade of life, although both earlier and later onset can occur. Upper limb involvement often develops with time, and affected individuals have weakness and atrophy of the intrinsic hand muscles. Other features may include distal sensory impairment, foot deformities, scoliosis, hypo- or hyperreflexia, spastic paraparesis, and neurogenic bladder. Electrophysiologic studies are compatible with an axonal sensorimotor peripheral neuropathy, and muscle and nerve biopsy show evidence of mitochondrial dysfunction with decreased activities of respiratory complexes, mtDNA deletions, and mitochondrial hyperplasia (summary by Fay et al., 2020).