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Editor—The ectodermal dysplasias comprise a heterogeneous group of inherited developmental disorders affecting tissue and organs of ectodermal origin. Their classification was developed by Freire-Maia and Pinheiro,1 with malformations of the hair, teeth, nails, and sweat glands as the major criteria. Ectodermal dysplasias are thus divided into 11 subgroups based on a minimum of two ectodermal signs with or without other developmental defects.
A Norwegian family with structural hair abnormalities associated with agenesis of the teeth is reported. The mode of inheritance is consistent with an autosomal dominant pattern.
The investigation for hair and tooth abnormalities in the family started with a then 16 year old boy (IV.3, fig 1), who was under dermatological treatment for an X linked ichthyosis. Blood lipoprotein electrophoresis showed increased migration of the low density lipoprotein (LDL) fraction compared to normal, consistent with steroid sulphatase deficiency. Interestingly, the blood LDL fraction in his mother, who suffered from dry skin, also showed increased migration, pointing towards carrier status for X linked ichthyosis.2His maternal grandfather was said also to have suffered from scaly skin. He had, however, died several years ago and clinical examination was therefore not possible. No other person in the family suffered from ichthyosis.
Further, it had been recognised that several persons on the paternal side of his family suffered from stiff and rough hair that seemed to break easily.
The boy had preferred to keep his hair short because it then was easier to treat the scaling of the scalp. He had therefore not been aware of increased breakage of hair. However, his hair felt rough and stiff (fig 2), and there was a discrete area of partial alopecia on the top of his head. Scanning electron microscopy of his hair showed twisted hair shafts combined with longitudinal grooves, pili torti et canaliculi (fig 3). He also had agenesis of the lower premolar teeth (35 and 45) (fig 4). There was no gingival fibrosis and no nail abnormality. The boy was of normal intelligence, had normal sweating and normal hearing, no generalised hypertrichosis, and no ophthalmological abnormalities.
The younger of his two sisters (IV.5, fig 1) had neither hair abnormalities nor agenesis of the teeth. The older of his two sisters (IV.4) also had agenesis of the teeth (12 and 22) (fig 5). She had no problems with breakage of hair and scanning electron microscopy of her hair showed no structural hair changes.
Hair samples from his mother showed no alterations. However, hair samples from both his father (III.2) (fig 6) and his paternal grandfather (II.1) (fig 7) showed pili torti et canaliculi. They also both had agenesis of the upper lateral teeth (12 and 22).
His great grandfather (I.1), the father of his paternal grandfather, was also said to have had stiff and rough hair and absence of teeth.
His paternal grandfather had four sibs, two sisters and two brothers. The hair of the only remaining sister (II.2) showed pili canaliculi and she also had dental abnormalities. She was not examined clinically, but provided hair samples for scanning electron microscopy. The hair and teeth of both her children, two sisters, were normal. Two out of three of the children of the remaining sibs, III.5 and III.6, showed similar hair abnormalities, pili torti et canaliculi (fig 8). They were said to have certain teeth missing. The son of III.5 had pili torti et canaliculi and agenesis of certain teeth.
The hair samples were fixed onto probe with double sided sticky tape, coated with a 30 nm layer of gold/palladium alloy in a Polaron E 5100 Sputter Coater (Polaron Equipment Ltd, Watford, UK), and the specimens were then examined and photographed in a Philips SEM 515 microscope (Philips, Eindhoven, The Netherlands).
So far, seven other pure ectodermal dysplasias with combined defects of hair and teeth have been described: (1) the oculodentodigital syndrome,3 (2) hypertrichosis and dental defects, (3) gingival fibromatosis and hypertrichosis, (4) trichodental dysplasia,4-6 (5) ectrodactyly-ectodermal dysplasia with normal lip and palate, (6) uncombable hair-retinal pigmentary dystrophy-juvenile cataract-brachymetacarpia, and (7) familial clefting syndrome with ectropion and dental anomaly.
The absence of pathological findings in tissue/organs other than the hair and teeth rules out the oculodentodigital syndrome, gingival fibromatosis and hypertrichosis syndrome, ectrodactyly-ectodermal dysplasia with normal lip and palate, uncombable hair-retinal pigmentary dystrophy-juvenile cataract-brachymetacarpia, and familial clefting syndrome with ectropion and dental anomaly. The dental abnormalities in (2) consist of persistence of deciduous teeth, delayed eruption, and the hypertrichosis is localised or generalised. In (4) trichodental dysplasia, missing teeth, peg shaped incisors, and shell teeth are the most common dental abnormalities.4-6 The hair is fine, sparse, dull, and slow growing.
Congenital absence of teeth is most probably autosomal dominantly inherited.7 It has been speculated that a common genetic defect may give rise to different phenotypic manifestations, including missing, malformed, and even ectopic and malpositioned teeth. The maxillary teeth that develop in the critical marginal areas of the dental lamina, namely the lateral incisors, canines, and second premolars, seem most susceptible.8
The findings in our patients, with different phenotypic manifestations of agenesis of the premolars or lateral incisors, point towards an autosomal dominant mode of inheritance. The sister IV.4 of patient IV.3 only showed agenesis of certain teeth and no pili torti et canaliculi on scanning electron microscopy. This is probably the result of variable expression of the ectodermal dysplasia.
Congenital pili torti et canaliculi is a hair shaft abnormality that has previously been described in Marie Unna hypotrichosis, and together with cleft lip/palate in the EEC-syndrome. The alopecia in Marie Unna hypotrichosis resembles androgenetic alopecia, but, in addition, hair loss occurs at the perimeter of the scalp as well, giving the patients monk-like features.9 In the EEC syndrome, several other pathological findings are present,10 not seen in any of our patients.
In conclusion, the combination of pili torti et canaliculi and dental abnormalities has not been described before and could represent a new pure hair-tooth ectodermal dysplasia.