Atrophoderma vermiculata, a form of keratosis pilaris atrophicans, typically presents in childhood with erythema and follicular keratotic papules that slowly progress to characteristic atrophy, which has been described as worm-eaten, reticular, or honeycomb, and occurs on the cheeks, preauricular area, and forehead. More rarely, the atrophy may extend to the upper lip, helices, ear lobes, and, in some cases, the limbs. The degree of inflammation, the presence of milia, and the extent of follicular plugs are variable (summary by Luria and Conologue, 2009).

FBLN5-related cutis laxa is characterized by cutis laxa, early childhood-onset pulmonary emphysema, peripheral pulmonary artery stenosis, and other evidence of a generalized connective disorder such as inguinal hernias and hollow viscus diverticula (e.g., intestine, bladder). Occasionally, supravalvar aortic stenosis is observed. Intrafamilial variability in age of onset is observed. Cardiorespiratory failure from complications of pulmonary emphysema (respiratory or cardiac insufficiency) is the most common cause of death.

Aromatic L-amino acid decarboxylase deficiency (AADCD) is an autosomal recessive inborn error in neurotransmitter metabolism that leads to combined serotonin and catecholamine deficiency (Abeling et al., 2000). The disorder is clinically characterized by vegetative symptoms, oculogyric crises, dystonia, and severe neurologic dysfunction, usually beginning in infancy or childhood (summary by Brun et al., 2010).

A rare disorder characterised by tetralogy of Fallot, minor facial anomalies, and severe intellectual deficiency and growth delay. Dysmorphic features include large, protruding, abnormally modelled ears and broad nasal root. Microcephaly and syndactyly of second and third toes have also been recorded. All patients have severe intellectual deficiency. The condition is transmitted as an autosomal recessive trait.

Waardenburg syndrome type II (WS2) is an auditory-pigmentary syndrome characterized by pigmentary abnormalities of the hair, skin, and eyes; congenital sensorineural hearing loss; and the absence of 'dystopia canthorum,' the lateral displacement of the inner canthus of each eye, which is seen in some other forms of WS (Hughes et al., 1994). WS type 2B (WS2B) maps to chromosome 1p. Waardenburg syndrome type 2 is genetically heterogeneous (see WS2A; 193510). For a description of other clinical variants of Waardenburg syndrome, see WS1 (193500), WS3 (148820), and WS4 (277580).

A rare syndrome described in two sisters of Mennonite descent, with characteristics of sparse hair, osteopenia, intellectual disability, minor facial abnormalities, joint laxity and hypotonia. There have been no further descriptions in the literature since 1992.

Laurin-Sandrow syndrome (LSS) is an autosomal dominant disorder characterized by polysyndactyly of hands and feet, mirror image duplication of feet, and nasal defects (hypoplastic alae nasi, short columella), in connection with absent patella and duplicated fibula (summary by Lohan et al., 2014).

ALS2-related disorder involves retrograde degeneration of the upper motor neurons of the pyramidal tracts and comprises a clinical continuum of the following three phenotypes: Infantile ascending hereditary spastic paraplegia (IAHSP), characterized by onset of spasticity with increased reflexes and sustained clonus of the lower limbs within the first two years of life, progressive weakness and spasticity of the upper limbs by age seven to eight years, and wheelchair dependence in the second decade with progression toward severe spastic tetraparesis and a pseudobulbar syndrome caused by progressive cranial nerve involvement. Juvenile primary lateral sclerosis (JPLS), characterized by upper motor neuron findings of pseudobulbar palsy and spastic quadriplegia without dementia or cerebellar, extrapyramidal, or sensory signs. Juvenile amyotrophic lateral sclerosis (JALS or ALS2), characterized by onset between ages three and 20 years. All affected individuals show a spastic pseudobulbar syndrome (spasticity of speech and swallowing) together with spastic paraplegia. Some individuals are bedridden by age 12 to 50 years.

This multisystem disorder is characterized by moyamoya disease, short stature, hypergonadotropic hypogonadism, and facial dysmorphism. Other variable features include dilated cardiomyopathy, premature graying of the hair, and early-onset cataracts. Moyamoya disease is a progressive cerebrovascular disorder characterized by stenosis or occlusion of the internal carotid arteries and the main branches, leading to the development of small collateral vessels (moyamoya vessels) at the base of the brain. Affected individuals can develop acute neurologic events due to stroke-like episodes (summary by Miskinyte et al., 2011). For a general phenotypic description and a discussion of genetic heterogeneity of moyamoya disease, see MYMY1 (252350).

PRRT2-associated paroxysmal movement disorders (PRRT2-PxMD) include paroxysmal kinesigenic dyskinesia (PKD), benign familial infantile epilepsy (BFIE), paroxysmal kinesigenic dyskinesia with infantile convulsions (PKD/IC), and hemiplegic migraine (HM). In addition, PRRT2 pathogenic variants have been identified in other childhood-onset movement disorders and different types of seizures, suggesting that the understanding of the spectrum of PRRT2-PxMD is still evolving. The paroxysmal attacks in PKD are characterized by dystonia, choreoathetosis, and less commonly ballismus. The seizures of BFIE are usually focal with or without generalization. Thirty percent of PRRT2-associated PKD is associated with BFIE and is referred to as PKD/IC.