Occipital horn syndrome (OHS) is a rare connective tissue disorder characterized by hyperelastic and bruisable skin, hernias, bladder diverticula, hyperextensible joints, varicosities, and multiple skeletal abnormalities. The disorder is sometimes accompanied by mild neurologic impairment, and bony abnormalities of the occiput are a common feature, giving rise to the name (summary by Das et al., 1995).

Autosomal recessive keratitis-ichthyosis-deafness syndrome (KIDAR) is characterized by neonatal-onset ichthyotic erythroderma and profound sensorineural deafness, with failure to thrive and developmental delay in childhood. Severe corneal scarring with vision loss has been observed in adulthood. Low plasma copper and ceruloplasmin levels have been reported in some patients (Alsaif et al., 2019; Boyden et al., 2019). An autosomal dominant form of KID syndrome (KIDAD; 148210) is caused by mutation in the GJB2 gene (121011) on chromosome 13q12. Mutation in the AP1S1 gene (603531) causes a disorder with overlapping features (MEDNIK; 609313).

A rare disorder of mineral absorption and transport characterized by hypocupremia that manifests as failure to thrive, mild anemia, repeated seizures, hypotonia and seborrheic skin. Spurring of the femur and tibia are also noted on radiographic imaging. Symptoms are reversible or improve with supplements of oral copper. There have been no further descriptions in the literature since 1982.

Congenital disorder of glycosylation type IIp (CDG2P) is an autosomal recessive metabolic disorder characterized by mild liver dysfunction, which may be found incidentally during adolescence. Laboratory abnormalities include elevated liver enzymes and alkaline phosphatase, coagulation factor deficiencies, hypercholesterolemia, and low ceruloplasmin. Serum isoelectric focusing of proteins shows a combined defect of N- and O-glycosylation, suggestive of a Golgi defect (summary by Jansen et al., 2016). For an overview of congenital disorders of glycosylation, see CDG1A (212065) and CDG2A (212066).

Immunodeficiency-47 (IMD47) is an X-linked recessive complex syndrome characterized by liver dysfunction, recurrent bacterial infections, hypogammaglobulinemia, and defective glycosylation of serum proteins. Some patients also have neurologic abnormalities (summary by Jansen et al., 2016).

A rare congenital disorder of glycosylation caused by mutations in the COG2 gene and with characteristics of normal presentation at birth, followed by progressive deterioration with postnatal microcephaly, developmental delay, intellectual disability, seizures, spastic quadriplegia, liver dysfunction, hypocupremia and hypoceruloplasminemia in the first year of life. Diffuse cerebral atrophy and thin corpus callosum may be observed on brain MRI.

Huppke-Brendel syndrome (HBS) is characterized by bilateral congenital cataracts, sensorineural hearing loss, and severe developmental delay. To date, six individuals with HBS have been reported in the literature. All presented in infancy with axial hypotonia; motor delay was apparent in the first few months of life with lack of head control and paucity of limb movement. Seizures have been reported infrequently. In all individuals described to date serum copper and ceruloplasmin levels were very low or undetectable. Brain MRI examination showed hypomyelination, cerebellar hypoplasia mainly affecting the vermis, and wide subarachnoid spaces. None of the individuals reported to date were able to sit or walk independently. All affected individuals died between age ten months and six years.