Sialuria

In sialuria, free sialic acid accumulates in the cytoplasm and gram quantities of neuraminic acid are secreted in the urine. The metabolic defect involves lack of feedback inhibition of UDP-GlcNAc 2-epimerase by CMP-Neu5Ac, resulting in constitutive overproduction of free Neu5Ac. Clinical features include variable degrees of developmental delay, coarse facial features and hepatomegaly. Sialuria inheritance is autosomal dominant.

Congenital myopathy 3 with rigid spine

An autosomal recessive, slowly progressive muscular disorder apparent from birth or early childhood and characterized by hypotonia, proximal muscle weakness, poor axial muscle strength, scoliosis and neck weakness, and a variable degree of spinal rigidity. Most patients remain ambulatory. Early ventilatory insufficiency may lead to death by respiratory failure. Additional features may include facial muscle weakness, amyotrophy, joint contractures, distal hyperlaxity, pulmonary hypertension with secondary cardiac dysfunction, and insulin resistance in patients with a low BMI. Skeletal muscle biopsy typically shows multiminicores and other abnormal non-specific myopathic findings.

Congenital myopathy 6 with ophthalmoplegia

A muscular disorder characterized by mild-to-moderate muscle weakness, ophthalmoplegia, and contractures at birth in some patients. Muscle biopsies from patients show predominance of type 1 fibers and small or absent type 2A fibers. The disease is non-progressive or it progresses very slowly. Inheritance is autosomal dominant or recessive.

Myopathy, X-linked, with excessive autophagy

A muscle disorder characterized by childhood early onset of a slowly progressive proximal limb muscle weakness (especially in legs) and elevation of serum creatine kinase, without evidence of cardiac, respiratory or central nervous system involvement. Histopathological analysis reveals diseased muscle fibers that are not necrotic, but show abnormal autophagic vacuolation as a manifestation of excessive autophagic activity in skeletal muscle cells.

Inclusion body myopathy with early-onset Paget disease with or without frontotemporal dementia 1

An autosomal dominant disease characterized by disabling muscle weakness clinically resembling to limb girdle muscular dystrophy, osteolytic bone lesions consistent with Paget disease, and premature frontotemporal dementia. Clinical features show incomplete penetrance.

Inclusion body myopathy with early-onset Paget disease with or without frontotemporal dementia 2

An autosomal dominant disease characterized by disabling muscle weakness clinically resembling to limb girdle muscular dystrophy, osteolytic bone lesions consistent with Paget disease, and premature frontotemporal dementia. Clinical features show incomplete penetrance.

Inclusion body myopathy with early-onset Paget disease with or without frontotemporal dementia 3

An autosomal dominant disease characterized by disabling muscle weakness clinically resembling to limb girdle muscular dystrophy, osteolytic bone lesions consistent with Paget disease, and premature frontotemporal dementia. Clinical features show incomplete penetrance.

Myopathy, myofibrillar, 9, with early respiratory failure

An autosomal dominant myopathy characterized by adulthood onset of weakness in proximal, distal, axial and respiratory muscles. Pelvic girdle weakness, foot drop and neck weakness are the main symptoms at onset, but ultimately the weakness usually involves the proximal compartment of both upper and lower limbs. Additional features include variable degrees of Achilles tendon contractures, spinal rigidity and muscle hypertrophy. Respiratory involvement often leads to requirement for non-invasive ventilation support.

Amyotrophic lateral sclerosis 23

A form of amyotrophic lateral sclerosis, a neurodegenerative disorder affecting upper motor neurons in the brain and lower motor neurons in the brain stem and spinal cord, resulting in fatal paralysis. Sensory abnormalities are absent. The pathologic hallmarks of the disease include pallor of the corticospinal tract due to loss of motor neurons, presence of ubiquitin-positive inclusions within surviving motor neurons, and deposition of pathologic aggregates. The etiology of amyotrophic lateral sclerosis is likely to be multifactorial, involving both genetic and environmental factors. The disease is inherited in 5-10% of the cases. ALS23 is an autosomal dominant form with incomplete penetrance.