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    Skin Related Disorders:

 

Oculocutaneous Albinism

Oculocutaneous albinism (OCA) is a heterogeneous group of congenital disorders characterized by hypopigmentation of skin, hair, and eyes associated with other developmental ocular defects. OCA patients are often considered as legally blind and in India, it is one of the 4 major causes of childhood blindness. Long-term sun exposure greatly increases the risk of skin damage and an aggressive form of skin cancer called melanoma, in people with this condition. Mutations in genes regulating the multistep process of melanin biosynthesis cause this spectrum of disorders. The four classical types of oculocutaneous albinism are designated as OCA1 (OCA1A: MIM: 203100 and OCA1B: MIM: 606952), OCA2 ( MIM: 203200), OCA3 ( MIM: 203290) and OCA4 ( MIM: 606574) caused by TYR, OCA2, TYRP1 and SLC45A2 genes, respectively. OCA1 is characterized by white hair, very pale skin, and light-colored irises. OCA2 and OCA4 have overlapping clinical features (a creamy white color and hair may be light yellow, blond, or light brown) that are generally less severe than OCA1. OCA3 affected individuals have reddish-brown skin, ginger or red hair and hazel or brown irises with milder vision abnormalities than the other forms of OCA. Overall, an estimated 1 in 20,000-30,000 people worldwide are born with oculocutaneous albinism however, the frequency differs from country to country. In India, OCA1 is the most prevalent type of OCA followed by OCA2.

Hermansky-Pudlak Syndrome ( MIM: 203300)

It is a rare autosomal recessive disorder characterised by oculocutaneous albinism, bleeding, and lysosomal ceroid storage result from defects of multiple cytoplasmic organelles: melanosomes, platelet-dense granules, and lysosomes. Hermansky-Pudlak syndrome (HPS) can be caused by mutation in several genes: HPS1 ( MIM: 604982), HPS3 ( MIM: 606118), HPS4 ( MIM: 606682), HPS5 ( MIM: 607521), and HPS6 ( MIM: 607522). HPS2 ( MIM: 608233), AP3B1 ( MIM: 603401), DTNBP1 ( MIM: 607145) and BLOC1S3 ( MIM: 609762).

                                The database presently holds the data for HPSI only.

H syndrome ( MIM: 612391)

H syndrome is a recently reported autosomal-recessive disorder characterized by cutaneous hyperpigmentation, hypertrichosis, hepatosplenomegaly, heart anomalies, hearing loss, hypogonadism, short stature, hallux valgus, and fixed flexion contractures of the toe joints and the proximal interphalangeal joints. It is caused by mutations in the SLC29A3 gene, which encodes the equilibrative nucleoside transporter hENT3.

Dyskeratosis congenita ( MIM: 305000)

The disease mainly affects the integumentary system with a major consequence being anomalies of the bone marrow. The disorder is characterised by premature aging with cutaneous pigmentation, dystrophy of the nails, leukoplakia of the oral mucosa, continuous lacrimation due to atresia of the lacrimal ducts, often thrombocytopenia, anemia, and in most cases testicular atrophy. Only males are affected in a pattern consistent with X-linked recessive inheritance as a result of one or more mutations in the long arm of the X chromosome in the gene DKC1. This may result in specific issues related to dysfunctional rRNA and perhaps a graver phenotype.

  Incontinentia pigmenti  ( MIM: 308300 )

Incontinentia pigmenti is a X-linked dominant genodermatosis and is usually lethal prenatally in males. However in affected females it causes highly variable abnormalities of the skin, hair, nails, teeth, eyes, and central nervous system with extremely skewed X-inactivation. The prominent skin signs occur in 4 classic cutaneous stages: perinatal inflammatory vesicles, verrucous patches, a distinctive pattern of hyperpigmentation, and dermal scarring. Familial incontinentia pigmenti is caused by mutations in the NEMO gene.