Description, Causes and Risk Factors:
Tightly coiled hair, oval in cross-section, with the texture of wool.
Woolly hair is a rare congenital abnormality of structure of scalp hair. It is marked by extreme kinkiness of hair in Caucasians. Woolly hair is either already present at birth or appears in the first months of life. The curls, with an average diameter of 0.5 cm, lie closely together and usually make the hair difficult to comb; in addition, the hair may be more fragile than usual. The hair growth rate is usually normal but the anagen phase may be truncated, with the result that the hair does not grow to be long. The hair shaft exhibits an elliptical cross section, an axial rotation and a kinked formation. A cirumscribed occurence of woolly hair in the form of a woolly hair nevus is distingushed from the forms affecting the entire scalp. The latter forms are autosomal dominant woolly hair (hereditary woolly hair) or, far less frequently, autosomal recessive hereditary woolly hair (familial woolly hair). Autosomal recessive woolly hair can be syndromic and therefore accompained by palmoplantar hyperkeratosis and heart abnormalities.
Types: Autosomal dominant woolly hair and autosomal recessive woolly hair.
A new gene that determines the texture in hair has been discovered in humans. Researchers from Columbia University Medical Center have found the new gene. The study about the new gene involved in hair texture has been published recently in the prestigious scientific journal Nature Genetics. The new gene, named P2RY5, is said to be the cause of hereditary "woolly hair," that is, the type of hair that is coarse, dry, and curled and sparse. They demonstrated that an alteration (mutation) on this P2RY5 gene is responsible for this type of hair.
Autosomal dominant hereditary woolly hair is more commonly encountered than the autosomal recessive form. The mode of transmisson of the latter is still debated. The etiology of diffuse partial woolly hair and of sporadically occurring woolly hair neveu is unknown. A follicular mosaicism (the condition in which an organism has two or more cell populations that differ in genetic makeup) can likely be assumed, while an audosomal dominant transmisson is also discussed for diffuse partial woolly hair.
The prevalence of the syndrome is about 1 person in 100000.
Patients with autosomal dominant woolly hair form exhibit strongly curled hair at birth or in the first few months of life. The curl diameter goes up to approximately 0.5 cm. The hair is difficult to brush and partially breaks off. Growth rate is normal, while the anagen phase be interrupted or shortened. In cases of truncated anagen phase or simultaneous occurrence of trichorrhexis nodosa, which is responsible for increased hair fragility, the hair does not grow to be very long. The average diameter of the hair shaft can be normal or reduced and the hair color is typically normal, although several cases of hypopigmentation of the hair have been described. The woolly hair is most evident in childhood; in adulthood the severity of the disorder can be lessen, and then adults often exhibit markedly wavy hair.
Familial woolly hair is present at birth. Tightly-curled, thin-caliber hair most often grows to be only 2 or 3 cm long due to the truncated anagen phase. The hair is normally lighter than that of unaffected family members, and in some cases it is white-blond. The body hair is short, light, and relatively sparse and a rarefaction of lateral eyebrows is observed.
A thorough dermatological examination with an evaluation of the entire integument including the hair, nails, and cuticles is the basic prerequisite for making a diagnosis and probably can draw attention to an associated syndrome. The examination of the hair shafts is carried out by light and electro microscopy, revealing the elliptical cross section, variation in caliber, axis rotation and kinked formation as well as non-homogeneous keratinisation. In some cases trichorrhexis nodosa is evident. If necessary the anagen/catagen ratio can be determined using a trichograms. A scalp biopsy is generally not necessary. In cases of diffuse partial woolly hair an increase in intermediate follicles can be detected histopathologically. An ophthalmologic examination is recommended for all patients with woolly hair. If the presence of a syndrome is suspected, an extensive internal and especially cardiological diagnostic investigation is necessary. Genetic analysis can be carried out if the gene locus is known. This is only the case for Naxos disease.
Genetic counselling: A gene locus for hereditary woolly hair is yet to be found. The genetic evidence for an autosomal recessive transmission is imcomplete, but seems obvious in view of occurrence of woolly hair in a sibling pair with healthy parents. The gene locus responsible for Naxos disease has been discovered. It entails a plakoglobin genetic defect located on chromosome 17q21. A desmoplakin genetic defect located on chromosome 6p23-24 accounts for dilated cardiomyopathy in combination with familial woolly hair and epidermolytic striated palmoplantar keratoderma.
No treatment for woolly hair is currently available. Physically and chemically, traumatic cosmetic measures should be avoided. Woolly hair is most evidence in childhood; the manifestation often becomes significantly less severe in adulthood, especially in the autosomal dominant hereditary forms. In syndromic occurrence of palmoplantar keratosis a symptomatic treatment involving the mechanical abrasion of the hyperkeratosis and moisturizing measures are effective. In the case of heart anomalies intensive internal and cardiological care is necessary. The pharmaceutical treatment of arrhythmias and anticoagulants as a prophylactic measure for embolic thromboses are recommended; in cases of disturbed stimulus conduction it may be necessary to consider implanting a pacemaker. The final option for treating therapy-resistant dilated cardiomyopathy is a heart transplant.
NOTE: The above information is for processing purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.
DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.
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