Cryptorchidism, or failure of testicular descent, is a common human congenital abnormality with a multifactorial etiology that likely reflects the involvement of endocrine, environmental, and hereditary factors. Cryptorchidism can result in infertility and increases risk for testicular tumors. Testicular descent from abdomen to scrotum occurs in 2 distinct phases: the transabdominal phase and the inguinoscrotal phase (summary by Gorlov et al., 2002).

Underdevelopment of part or all of the male external reproductive organs (which include the penis, the scrotum and the urethra).

Absence of neurologic reflexes such as the knee-jerk reaction.

Obstructive sleep apnea is a common, chronic, complex disease associated with serious cardiovascular and neuropsychologic sequelae and with substantial social and economic costs (Palmer et al., 2003).

A type of Developmental delay characterized by a delay in acquiring motor skills.

A lack of strength of the proximal muscles.

An abnormality in which the nuclei of sarcomeres take on an abnormally central localization (or in which this feature is found in an increased proportion of muscle cells).

Congenital myopathy-1B (CMYO1B) is an autosomal recessive disorder of skeletal muscle characterized by severe hypotonia and generalized muscle weakness apparent soon after birth or in early childhood with delayed motor development, generalized muscle weakness and atrophy, and difficulty walking or running. Affected individuals show proximal muscle weakness with axial and shoulder girdle involvement, external ophthalmoplegia, and bulbar weakness, often resulting in feeding difficulties and respiratory insufficiency. Orthopedic complications such as joint laxity, distal contractures, hip dislocation, cleft palate, and scoliosis are commonly observed. Serum creatine kinase is normal. The phenotype is variable in severity (Jungbluth et al., 2005; Bharucha-Goebel et al., 2013). Some patients show symptoms in utero, including reduced fetal movements, polyhydramnios, and intrauterine growth restriction. The most severely affected patients present in utero with fetal akinesia, arthrogryposis, and lung hypoplasia resulting in fetal or perinatal death (McKie et al., 2014). Skeletal muscle biopsy of patients with recessive RYR1 mutations can show variable features, including multiminicores (Ferreiro and Fardeau, 2002), central cores (Jungbluth et al., 2002), congenital fiber-type disproportion (CFTD) (Monnier et al., 2009), and centronuclear myopathy (Wilmshurst et al., 2010). For a discussion of genetic heterogeneity of congenital myopathy, see CMYO1A (117000).

An abnormal predominance of type I muscle fibers (in general, this feature can only be observed on muscle biopsy).

Muscular hypotonia (abnormally low muscle tone) manifesting in the neonatal period.

Streaming or smearing of the Z band, which is then no longer confined to a narrow zone which bisects the I band. The Z disk may extend across the I band or the entire sarcomere in a zigzag manner. Focal thickening, smudging, and blurring of the Z band takes place concurrently. Myofibrillar disorganization is a frequent but not invariable accompanying change.

Muscle fibers degeneration resulting in fatty replacement of skeletal muscle fibers

Fasciculations or fibrillation affecting the tongue muscle.

Diminished amniotic fluid volume in pregnancy.

An abnormal reduction in quantity or strength of fetal movements.