ATP6V0A2-related cutis laxa is characterized by generalized cutis laxa, findings associated with generalized connective tissue disorder, developmental delays, and a variety of neurologic findings including abnormality on brain MRI. At birth, hypotonia, overfolded skin, and distinctive facial features are present and enlarged fontanelles are often observed. During childhood, the characteristic facial features and thick or coarse hair may become quite pronounced. The skin findings decrease with age, although easy bruising and Ehlers-Danlos-like scars have been described in some. In most (not all) affected individuals, cortical and cerebellar malformations are observed on brain MRI. Nearly all affected individuals have developmental delays, seizures, and neurologic regression.

Individuals with monilethrix have normal hair at birth, but within the first few months of life develop fragile, brittle hair that tends to fracture and produce varying degrees of dystrophic alopecia. In the mildest forms, only the occipital regions of the scalp are involved; however, in severe forms the eyebrows, eyelashes, and secondary sexual hair may also be involved. Follicular hyperkeratosis with predilection for the scalp, nape of neck, and extensor surfaces of the upper arm and thighs is also a characteristic finding in these patients. Light microscopic examination is diagnostic and reveals elliptical nodes of normal thickness and intermittent constrictions (internodes) at which the hair easily breaks. There may be spontaneous improvement with time, especially during puberty and pregnancy, but the condition never resolves completely (summary by Zlotogorski et al., 2006). An autosomal recessive form of monilethrix-like congenital hypotrichosis (see 607903) is caused by mutation in the DSG4 gene (607892). The clinical picture of autosomal recessive monilethrix is more severe than the dominant form, with more extensive alopecia of the scalp, body, and limbs, and a papular rash involving the extremities and periumbilical region (Zlotogorski et al., 2006). The term monilethrix derives from the Latin word for necklace and the Greek for hair (Schweizer, 2006).

Trichothiodystrophy is a rare autosomal recessive disorder in which patients have brittle, sulfur-deficient hair that displays a diagnostic alternating light and dark banding pattern, called 'tiger tail banding,' under polarizing microscopy. TTD patients display a wide variety of clinical features, including cutaneous, neurologic, and growth abnormalities. Common additional clinical features are ichthyosis, intellectual/developmental disabilities, decreased fertility, abnormal characteristics at birth, ocular abnormalities, short stature, and infections. There are both photosensitive and nonphotosensitive forms of the disorder (summary by Faghri et al., 2008). Sabinas brittle hair syndrome (211390) is another form of nonphotosensitive TTD. For a discussion of genetic heterogeneity of trichothiodystrophy, see 601675.

Koolen-de Vries syndrome (KdVS) is characterized by congenital malformations, developmental delay / intellectual disability, neonatal/childhood hypotonia, epilepsy, dysmorphisms, and behavioral features. Psychomotor developmental delay is noted in all individuals from an early age. The majority of individuals with KdVS function in the mild-to-moderate range of intellectual disability. Other findings include speech and language delay (100%), epilepsy (~33%), congenital heart defects (25%-50%), renal and urologic anomalies (25%-50%), and cryptorchidism. Behavior in most is described as friendly, amiable, and cooperative.

This syndrome has characteristics of neonatal teeth, trichodystrophy and malformations of the hands and feet. To date, it has been reported in 21 patients and is transmitted as an autosomal dominant trait.