Structural and molecular hair abnormalities in trichothiodystrophy

The face of Non-photosensitive trichothiodystrophy phenotypic spectrum: A subsequent study on paediatric population

BACKGROUND

Non-photosensitive trichothiodystrophies (TTDs) are a diverse group of genodermatoses within the subset of conditions known as "sulphur-deficient brittle hair" syndromes. A part of them has only recently been identified, revealing novel causative genes and very rare phenotypes of these genetic skin disorders. At the same time, the molecular basis of previously published and unresolved cases has been revealed through the introduction of innovative genetic techniques. We have previously described the facial phenotype of patients with the Photosensitive form of TTD during childhood. This study marks the beginning of an effort to expand the analysis to include individuals of the same age who do not have photosensitivity.

METHODS

A total of 26 facial portraits of TTD paediatric patients with Non-photosensitivity from the literature were analysed using computer-aided technologies, and their facial features were examined through a detailed clinical review.

RESULTS

Distinct facial features were identified in both Photosensitive and Non-photosensitive TTDs.

CONCLUSION

The present study has comprehensively elucidated the facial features in TTDs, encompassing the Non-photosensitive clinical spectrum.

Debilitating hip degeneration in trichothiodystrophy: Association with ERCC2/XPD mutations, osteosclerosis, osteopenia, coxa valga, contractures, and osteonecrosis

Trichothiodystrophy (TTD) is a rare, autosomal recessive, multisystem disorder of DNA repair and transcription with developmental delay and abnormalities in brain, eye, skin, nervous, and musculoskeletal systems. We followed a cohort of 37 patients with TTD at the National Institutes of Health (NIH) from 2001 to 2019 with a median age at last observation of 12 years (range 2-36). Some children with TTD developed rapidly debilitating hip degeneration (DHD): a distinctive pattern of hip pain, inability to walk, and avascular necrosis on imaging. Ten (27%) of the 37 patients had DHD at median age 8 years (range 5-12), followed by onset of imaging findings at median age 9 years (range 5-13). All 10 had mutations in the ERCC2/XPD gene. In 7 of the 10 affected patients, DHD rapidly became bilateral. DHD was associated with coxa valga, central osteosclerosis with peripheral osteopenia of the skeleton, and contractures/tightness of the lower limbs. Except for one patient, surgical interventions were generally not effective at preventing DHD. Four patients with DHD died at a median age of 11 years (range 9-15). TTD patients with ERCC2/XPD gene mutations have a high risk of musculoskeletal abnormalities and DHD leading to poor outcomes. Monitoring by history, physical examination, imaging, and by physical medicine and rehabilitation specialists may be warranted.

Trichothiodystrophy hair shafts display distinct ultrastructural features

Hair shafts from three trichothiodystrophy (TTD) patients with mutations in the ERCC2 (XPD) gene were examined by transmission electron microscopy. TTD is a rare, recessive disorder with mutations in several genes in the DNA repair/transcription pathway, including ERCC2. Unlike previous studies, the hair shafts were examined after relaxation of their structure by partial disulphide bond reduction in the presence of sodium dodecyl sulphate, permitting improved visualization. Compared with hair shafts of normal phenotype, TTD cuticle cells displayed aberrant marginal bands and exocuticle layers. Clusters of cells stained differently (light versus dark) in the cortex of aberrant shafts, and the keratin macrofibrils appeared much shorter in the cytoplasm. Considerable heterogeneity in these properties was evident among samples and even along the length of single hair shafts. The results are consistent with not only a paucity of high sulphur components, such as keratin-associated proteins, but also a profound imbalance in protein content and organization.

Metronidazole-Induced Hepatitis in a Teenager With Xeroderma Pigmentosum and Trichothiodystrophy Overlap

A teenage girl had the rare combined phenotype of xeroderma pigmentosum and trichothiodystrophy, resulting from mutations in the XPD (ERCC2) gene involved in nucleotide excision repair (NER). After treatment with antibiotics, including metronidazole for recurrent infections, she showed signs of acute and severe hepatotoxicity, which gradually resolved after withdrawal of the treatment. Cultured skin fibroblasts from the patient revealed cellular sensitivity to killing by metronidazole compared with cells from a range of other donors. This reveals that the metronidazole sensitivity was an intrinsic property of her cells. It is well recognized that patients with Cockayne syndrome, another NER disorder, are at high risk of metronidazole-induced hepatotoxicity, but this had not been reported in individuals with other NER disorders. We would urge extreme caution in the use of metronidazole in the management of individuals with the xeroderma pigmentosum and trichothiodystrophy overlap or trichothiodystrophy phenotypes.

Hair follicle dystrophy in a litter of domestic cats resembling lanceolate hair mutant mice

BACKGROUND

A new congenital hair-shaft abnormality resembling the lanceolate hair phenotype of rodents is described in a litter of four domestic short hair (DSH) cats. Data relating to hair shaft and follicle disorders remain scarce in veterinary medicine.

OBJECTIVES

To describe and compare structural abnormalities in these cats with other hair dystrophies in cats and other mammals.

ANIMALS

A DSH cat litter with progressive noninflammatory alopecia.

METHODS AND MATERIALS

Histopathological evaluation, scanning and transmission electron microscopy, and X-ray based element analysis defined the hair and skin changes in cats born with alopecia. Findings were compared to archival data from normal cats and lanceolate hair (Dsg4lahJ ) and Keratin 75 (Krt75tm1Der ) mutant mice.

RESULTS

Light and scanning electron microscopy of the hairs revealed lance- or spear-head shaped defects of the hair tip. Histological findings were swollen hair shafts, initially above the hair bulb matrix and later found in the distal parts of the telogen hair follicles, similar to those observed in Dsg4lahJ Krt75tm1Der mutant mice. Transmission electron microscopy of the hair shaft and hair follicles showed a loss in the normal structure of the guard hairs in the alopecic cats. There was a statistically significant decrease in sulfur content just below the defects in the hair shafts (trichothiodystrophy).

CONCLUSION AND CLINICAL IMPORTANCE

A rare form of congenital alopecia resulting in follicular dystrophy is described in cats which is similar to hair follicle and hair-shaft changes reported in several mutant mouse strains with single gene mutations in adhesion molecules or keratin genes.

ERCC2 mutations in two siblings with a severe trichothiodystrophy phenotype

BACKGROUND

Trichothiodystrophy (TTD) describes a group of rare genetic disorders of DNA repair, characterized by sulphur-deficient hair, skin anomalies and systemic complications like preterm delivery, neurological impairment, haematological and ophthalmological abnormalities and life-threatening infections.

OBJECTIVES

The aim of this case report was to investigate the contribution of the gene mutation to the phenotype.

METHODS

We describe the clinical and molecular characteristics of a family with two TTD-affected siblings who died before the age of 2 years.

RESULTS

The causal mutated gene is the ERCC2 gene, and one of the identified mutations is the c.2164C>T (p.Arg722Trp) variant. The association of this mutation with a severe TTD phenotype was suggested earlier in literature, and the present family adds further evidence to this hypothesis.

CONCLUSION

Accurate identification of the underlying genetic defect can guide the clinical follow-up and counselling of patients and their families.

PIBIDS syndrome in two Brazilian siblings

Trichothiodystrophy is a rare condition associated with autosomal recessive or X-linked dominant variants in the ERCC2, ERCC3, GTF2H5, MPLKIP, RNF113A or GTF2E2 genes. The genes associated to photosensitive trichothiodystrophy encode subunits of transcription factor IIH, involved in the nucleotide excision repair pathway. The disease is characterised by cysteine-deficient brittle hair along with other neuroectodermal abnormalities. It has a variable clinical expression and some cases might be associated with photosensitivity, resulting in the acronym PIBIDS (photosensitivity, ichthyosis, brittle hair, intellectual impairment, decreased fertility and short stature). We report clinical findings of two siblings diagnosed with trichothiodystrophy associated with marked photosensitivity.

Understanding photodermatoses associated with defective DNA repair: Photosensitive syndromes without associated cancer predisposition

Photodermatoses associated with defective DNA repair are a group of photosensitive hereditary skin disorders. In this review, we focus on diseases and syndromes with defective nucleotide excision repair that are not accompanied by an increased risk of cutaneous malignancies despite having photosensitivity. Specifically, the gene mutations and transcription defects, epidemiology, and clinical features of Cockayne syndrome, cerebro-oculo-facial-skeletal syndrome, ultraviolet-sensitive syndrome, and trichothiodystrophy will be discussed. These conditions may also have other extracutaneous involvement affecting the neurologic system and growth and development. Rigorous photoprotection remains an important component of the management of these inherited DNA repair-deficiency photodermatoses.

Cysteine Prevents the Reduction in Keratin Synthesis Induced by Iron Deficiency in Human Keratinocytes

L-cysteine is currently recognized as a conditionally essential sulphur amino acid. Besides contributing to many biological pathways, cysteine is a key component of the keratin protein by its ability to form disulfide bridges that confer strength and rigidity to the protein. In addition to cysteine, iron represents another critical factor in regulating keratins expression in epidermal tissues, as well as in hair follicle growth and maturation. By focusing on human keratinocytes, the aim of this study was to evaluate the effect of cysteine supplementation as nutraceutical on keratin biosynthesis, as well as to get an insight on the interplay of cysteine availability and cellular iron status in regulating keratins expression in vitro. Herein we demonstrate that cysteine promotes a significant up-regulation of keratins expression as a result of de novo protein synthesis, while the lack of iron impairs keratin expression. Interestingly, cysteine supplementation counteracts the adverse effect of iron deficiency on cellular keratin expression. This effect was likely mediated by the up-regulation of transferrin receptor and ferritin, the main cellular proteins involved in iron homeostasis, at last affecting the labile iron pool. In this manner, cysteine may also enhance the metabolic iron availability for DNA synthesis without creating a detrimental condition of iron overload. To the best of our knowledge, this is one of the first study in an in vitro keratinocyte model providing evidence that cysteine and iron cooperate for keratins expression, indicative of their central role in maintaining healthy epithelia.

Trichodystrophies: A hair-raising differential diagnosis

The appearance of an individual's hair is said to be reflective of internal health. Patients with hair shaft disorders commonly present with fragile, lusterless, sparse hair in addition to psychosocial distress. Hair shaft disorders may be hereditary or acquired and may present in children or adults. Due to the varied presentations, the differential diagnosis for hair is broad and often confusing. The authors present a question-by-question guide to help clinicians arrive at the correct diagnosis.

Mutations in the TTDN1 gene are associated with a distinct trichothiodystrophy phenotype

Trichothiodystrophy (TTD) is a rare multisystem disorder, characterized by sulfur deficient hair with alternating dark and light “tiger tail” banding on polarized light microscopy. TTD is caused by mutations in DNA repair/transcription genes XPD, XPB or TTDA, and in TTDN1, a gene of unknown function. While most TTD patients are photosensitive, patients with TTDN1 mutations were reported to be non-photosensitive. We followed a cohort of 36 TTD patients from 2001 to 2013. We describe 5 patients from 4 families with defects in the TTDN1 gene: 4 had no photosensitivity while 1 patient exhibited cutaneous burning. Deep phenotyping of our cohort revealed differences between the patients with and without TTDN1 mutations. Delayed bone age and seizure disorders were overrepresented in the TTDN1 group (p=0.009 and p=0.024, respectively), while some characteristic TTD clinical, laboratory, and imaging findings were absent. The 3 oldest TTDN1 patients displayed autistic behaviors in contrast to the characteristic friendly, socially interactive personality in the other patients. DNA sequencing revealed deletion mutations in TTDN1 ranging in size from a single base pair to over 120kb. These data identify a distinct phenotype relationship in TTD caused by TTDN1 mutations and suggest a different mechanism of disease.

Light microscopic hair abnormalities in children: retrospective review of 119 cases in a 10-year period

Abnormalities in the hair can be congenital or acquired conditions. Examples of genetic disorders with associated hair abnormalities include Menkes syndrome, Netherton syndrome, uncombable hair syndrome, trichothiodystrophy, and loose anagen hair syndrome. Acquired hair abnormalities can be associated with grooming or use of various hair products. There are many patterns of hair abnormalities that can be readily identified under a light microscope. We performed a retrospective review of 129 hair mount samples from 119 patients submitted to the pathology department for microscopic examination over a 10-year span (from January 2002 to December 2011). Of the 119 patients, 63 (53%) had morphologic changes in the hair samples. Thirty-seven patients (31%) showed morphologic changes compatible with specific diagnoses of various genetic conditions, including 25 cases of loose anagen hair syndrome, 6 cases of uncombable hair syndrome, 2 cases of Netherton syndrome, 3 cases of Menkes syndrome, and 1 case of trichothiodystrophy. The other changes were considered nonspecific or nondiagnostic, with trichorrhexis nodosa in 13 patients, presence of loose anagen hairs in 12 patients, and pili torti in 1 patient. We describe the light microscopic patterns of hair abnormalities, clinical findings, and molecular defects related to those genetic conditions. Our study indicates that hair examination can be a 1st-line investigation on various pediatric conditions.

Further insights in trichothiodistrophy: a clinical, microscopic, and ultrastructural study of 20 cases and literature review

BACKGROUND

Trichothiodistrophy (TTD) is a rare autosomal recessive condition that is characterized by a specific congenital hair shaft dysplasia caused by deficiency of sulfur associated with a wide spectrum of multisystem abnormalities. In this article, we study clinical, microscopic, and ultrastructural findings of 20 patients with TTD with the aim to add further insights regarding to this rare condition. Additionally, analyses of our results are compared with those extracted from the literature in order to enhance its comprehensibility.

MATERIALS AND METHODS

TWENTY CASES OF TTD WERE INCLUDED: 7 from Mexico and 14 from Spain. Clinical, microscopic, scanning electron microscopy (SEM) studies and X-ray microanalysis (XrMa) were carried out in all of them. Genetic studies were performed in all seven Mexican cases. Patients with xeroderma pigmentosum and xeroderma pigmentosum/TTD-complex were excluded.

RESULTS

Cuticular changes and longitudinal crests of the hair shaft were demonstrated. These crests were irregular, disorganized, following the hair longest axis. Hair shaft sulfur deficiency was disposed discontinuously and intermittently rather than uniformly. This severe decrease of sulfur contents was located close to the trichoschisis areas. Only five patients did not show related disturbances. Micro-dolichocephaly was observed in five cases and represented the most frequent facial dysmorphism found. It is also remarkable that all patients with urologic malformations also combined diverse neurologic disorders. Moreover, three Mexican sisters demonstrated the coexistence of scarce pubic vellus hair, developmental delay, onychodystrophy, and maxillar/mandibullar hypoplasia.

CONCLUSIONS

TTD phenotype has greatly varied from very subtle forms to severe alterations such as neurologic abnormalities, blindness, lamellar ichthyosis and gonadal malformations. Herein, a multisystem study should be performed mandatorily in patients diagnosed with TTD.

Hereditary Disorders with Defective Repair of UV-Induced DNA Damage

Nucleotide excision repair (NER) is an essential system for correcting ultraviolet (UV)—induced DNA damage. Lesions remaining in DNA due to reduced capacity of NER may result in cellular death, premature aging, mutagenesis and carcinogenesis of the skin. So, NER is an important protection against these changes. There are three representative genodermatoses resulting from genetic defects in NER: xeroderma pigmentosum (XP), Cockayne syndrome (CS), and trichothiodystrophy (TTD). In Japan, CS is similarly rare but XP is more common and TTD is less common compared to Western countries.

In 1998, we established the system for the diagnosis of these disorders and we have been performing DNA repair and genetic analysis for more than 400 samples since then. At present, there is no cure for any human genetic disorder. Early diagnosis and symptomatic treatment of neurological, ocular and dermatological abnormalities should contribute to prolonging life and elevating QOL in patients.

Dysmyelination not demyelination causes neurological symptoms in preweaned mice in a murine model of Cockayne syndrome

Cockayne syndrome (CS) is a rare autosomal recessive neurodegenerative disease that is associated with mutations in either of two transcription-coupled DNA repair genes, CSA or CSB. Mice with a targeted mutation in the Csb gene (Cs-b(m/m)) exhibit a milder phenotype compared with human patients with mutations in the orthologous CSB gene. Mice mutated in Csb were crossed with mice lacking Xpc (Xp-c(-/-)), the global genome repair gene, to enhance the pathological symptoms. These Cs-b(m/m).Xp-c(-/-) mice were normal at birth but exhibited progressive failure to thrive, whole-body wasting, and ataxia and died at approximately postnatal day 21. Characterization of Cs-b(m/m).Xp-c(-/-) brains at postnatal stages demonstrated widespread reduction of myelin basic protein (MBP) and myelin in the sensorimotor cortex, the stratum radiatum, the corpus callosum, and the anterior commissure. Quantification of individual axons by electron microscopy showed a reduction in both the number of myelinated axons and the average diameter of myelin surrounding the axons. There were no significant differences in proliferation or oligodendrocyte differentiation between Cs-b(m/m).Xp-c(-/-) and Cs-b(m/+).Xp-c(-/-) mice. Rather, Cs-b(m/m).Xp-c(-/-) oligodendrocytes were unable to generate sufficient MBP or to maintain the proper myelination during early development. Csb is a multifunctional protein regulating both repair and the transcriptional response to reactive oxygen through its interaction with histone acetylase p300 and the hypoxia-inducible factor (HIF)1 pathway. On the basis of our results, combined with that of others, we suggest that in Csb the transcriptional response predominates during early development, whereas a neurodegenerative response associated with repair deficits predominates in later life.

In vivo reflectance confocal microscopy: usefulness for diagnosing hair diseases

BACKGROUND

Reflectance confocal laser scanning microscopy (R-CSLM) is a new diagnostic technique which allows visualization of "optical intersections" within the epidermis and superficial layers of the dermis. Outlines of cells and their architecture are imaged and may be analyzed both horizontally and vertically to the skin surface. The method proved useful in early melanoma detection. We evaluated the potential usefulness of this method in a short series of patients with hair diseases.

MAIN OBSERVATIONS

Two healthy persons and 6 patients with hair diseases (1 with alopecia areata, 1 with androgenic alopecia and 4 with genetic hair shaft abnormalities) were examined with the use of Vivascope 1500. In all patients one scalp location and one location in the mid forearm were evaluated. R-CSLM examination gave in all cases high quality images of the hair shaft intersections, at 1µm intervals, which allowed detailed analysis of the hair structure. Hair follicles could be partly visualized at a depth of up to 200µm, which allowed analysis of only superficial parts of the hair follicles. An additional hurdle was bright reflection within the follicular ostia, which decreased the perception of details in these images. Hair could be best visualized, when analyzed on flat surfaces. Receiving good quality images from convex surfaces on the scalp required additional effort from the patient (to not move) and from the physician (to obtain best possible fit of the "optic window" to the scalp).

CONCLUSIONS

These preliminary data show that R-CSLM may develop into a valuable tool in evaluation of hair shaft diseases. Further development is needed to apply this technique in abnormalities of the hair follicle and the perifollicular area.

Ocular manifestations of trichothiodystrophy

OBJECTIVE

Trichothiodystrophy (TTD) is a rare, autosomal recessive disorder characterized by sulfur-deficient brittle hair and multisystem abnormalities. Many TTD patients have a defect in known DNA repair genes. This report systematically evaluates the ocular manifestations of the largest-to-date cohort of TTD patients and xeroderma pigmentosum (XP)/TTD patients.

DESIGN

Case series.

PARTICIPANTS

Thirty-two participants, ages 1 to 30 years, referred to the National Eye Institute for examination from 2001 to 2010; 25 had TTD and 7 had XP/TTD.

METHODS

Complete, age- and developmental stage-appropriate ophthalmic examination.

MAIN OUTCOME MEASURES

Visual acuity (VA), best-corrected VA, ocular motility, state of the ocular surface and corneal endothelial cell density, corneal diameter, and lens assessment.

RESULTS

Developmental abnormalities included microcornea (44% TTD), microphthalmia (8% TTD, 14% XP/TTD), nystagmus (40% TTD), and infantile cataracts (56% TTD, 86% XP/TTD). Corrective lenses were required by 65% of the participants, and decreased best-corrected VA was present in 28% of TTD patients and 71% of XP/TTD patients. Degenerative changes included dry eye (32% TTD, 57% XP/TTD) and ocular surface disease identified by ocular surface staining with fluorescein (32% TTD) that usually are exhibited by much older patients in the general population. The 2 oldest TTD patients exhibited clinical signs of retinal/macular degeneration. Four XP/TTD patients presented with corneal neovascularization.

CONCLUSIONS

These TTD and XP/TTD study participants had a wide variety of ocular findings including refractive error, infantile cataracts, microcornea, nystagmus, and dry eye/ocular surface disease. Although many of these can be ascribed to abnormal development--likely owing to abnormalities in basal transcription of critical genes--patients may also have a degenerative course.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosures may be found after the references.

High-risk pregnancy and neonatal complications in the DNA repair and transcription disorder trichothiodystrophy: report of 27 affected pregnancies

OBJECTIVE

To identify the frequency of pregnancy and neonatal complications in pregnancies carrying fetuses affected with trichothiodystrophy (TTD).

METHODS

We identified pregnancy and neonatal complications and serum screening results from mothers of TTD patients in a DNA repair diseases study from 2001 to 2011.

RESULTS

Pregnancy reports of 27 TTD patients and their 23 mothers were evaluated and 81% of the pregnancies had complications: 56% had preterm delivery, 30% had preeclampsia, 19% had placental abnormalities, 11% had HELLP syndrome, and 4% had an emergency c-section for fetal distress, while 44% had two or more complications. Only 19% of the pregnancies delivered at term without complications. Eight of the ten pregnancies tested had abnormal multiple marker results including elevated levels of human chorionic gonadotrophin. Eighty-five percent of the neonates had complications: 70% were low birth weight (<2500 g), 35% had birth weight < 10 centile for gestational age, 70% had NICU admission, 67% had a collodion membrane, and 31% of the 16 males had cryptorchidism. Cataracts were present in 54% of the TTD patients examined.

CONCLUSION

TTD is a multisystem disease that predisposes mothers of affected patients to substantial risks for pregnancy complications and TTD neonates have a high incidence of multiple abnormalities.

Light microscopy of the hair: a simple tool to "untangle" hair disorders

Light microscopy of the hair forms an important bedside clinical tool for the diagnosis of various disorders affecting the hair. Hair abnormalities can be seen in the primary diseases affecting the hair or as a secondary involvement of hair in diseases affecting the scalp. Hair abnormalities also form a part of various genodermatoses and syndromes. In this review, we have briefly highlighted the light microscopic appearance of various infectious and non-infectious conditions affecting the hair.

Revised nomenclature and classification of inherited ichthyoses: results of the First Ichthyosis Consensus Conference in Sorèze 2009

BACKGROUND

Inherited ichthyoses belong to a large, clinically and etiologically heterogeneous group of mendelian disorders of cornification, typically involving the entire integument. Over the recent years, much progress has been made defining their molecular causes. However, there is no internationally accepted classification and terminology.

OBJECTIVE

We sought to establish a consensus for the nomenclature and classification of inherited ichthyoses.

METHODS

The classification project started at the First World Conference on Ichthyosis in 2007. A large international network of expert clinicians, skin pathologists, and geneticists entertained an interactive dialogue over 2 years, eventually leading to the First Ichthyosis Consensus Conference held in Sorèze, France, on January 23 and 24, 2009, where subcommittees on different issues proposed terminology that was debated until consensus was reached.

RESULTS

It was agreed that currently the nosology should remain clinically based. "Syndromic" versus "nonsyndromic" forms provide a useful major subdivision. Several clinical terms and controversial disease names have been redefined: eg, the group caused by keratin mutations is referred to by the umbrella term, "keratinopathic ichthyosis"-under which are included epidermolytic ichthyosis, superficial epidermolytic ichthyosis, and ichthyosis Curth-Macklin. "Autosomal recessive congenital ichthyosis" is proposed as an umbrella term for the harlequin ichthyosis, lamellar ichthyosis, and the congenital ichthyosiform erythroderma group.

LIMITATIONS

As more becomes known about these diseases in the future, modifications will be needed.

CONCLUSION

We have achieved an international consensus for the classification of inherited ichthyosis that should be useful for all clinicians and can serve as reference point for future research.

Adverse effects of trichothiodystrophy DNA repair and transcription gene disorder on human fetal development

The effects of DNA repair and transcription gene abnormalities in human pre-natal life have never been studied. Trichothiodystrophy (TTD) is a rare (affected frequency of 10(-6)) recessive disorder caused by mutations in genes involved in nucleotide excision repair (NER) pathway and in transcription. Based on our novel clinical observations, we conducted a genetic epidemiologic study to investigate gestational outcomes associated with TTD. We compared pregnancies resulting in TTD-affected offspring (n = 24) with respect to abnormalities during their antenatal and neonatal periods to pregnancies resulting in their unaffected siblings (n = 18), accounting for correlation, and to population reference values. Significantly higher incidence of several severe gestational complications was noted in TTD-affected pregnancies. Small for gestational age (SGA) <10th percentile [Relative risk (RR ) = 9.3, 95% CI = 1.4-60.5, p = 0.02], SGA <3rd percentile (RR = 7.2, 95% CI = 1.1-48.1, p = 0.04), and neonatal intensive care unit (NICU) hospitalization (RR = 6.4, 95% CI = 1.4-29.5, p = 0.02) occurred more frequently among TTD-affected neonates compared with their unaffected siblings. Compared with reference values from general obstetrical population, pregnancies that resulted in TTD-affected infants were significantly more likely to be complicated by hemolysis, elevated liver enzymes and low platelets (HELLP) syndrome (RR = 35.7, 95% CI = 7.6-92.5, p = 0.0002), elevated mid-trimester maternal serum human chorionic gonadotropin (hCG) levels (RR = 14.3, 95% CI = 7.0-16.6, p < 0.0001), SGA <3rd percentile (RR = 13.9, 95% CI = 7.4-21.1, p < 0.0001), pre-term delivery (<32 weeks) (RR = 12.0, 95% CI = 4.9-21.6, p < 0.0001), pre-eclampsia (RR = 4.0, 95% CI = 1.6-7.4, p = 0.006), and decreased fetal movement (RR = 3.3, 95% CI = 1.6-5.2, p = 0.0018). Abnormal placental development is an underlying mechanism that may explain the constellation of observed complications in our study. Thus, we hypothesize that TTD DNA repair and transcription genes play an important role in normal human placental development.

'Relaxers' damage hair: evidence from amino acid analysis

BACKGROUND

'Relaxers' are used by more than two thirds of African females to straighten hair, with easy grooming and increased length often cited as reasons. A recent study reported relaxed hair lengths much shorter than expected, suggesting increased fragility; the potential for scalp inflammation and scarring alopecia remains unclear.

OBJECTIVE

To investigate the biochemical effects of 'relaxers' on hair.

METHODS

With informed consent, included participants represented 3 groups: natural hair, asymptomatic relaxed hair, and symptomatic (brittle) relaxed hair. Biochemical analysis was performed by using a Biochrom 30 amino acid analyzer. Differences in amino acid levels were assessed using either Wilcoxon rank sum test or matched-pairs signed-rank test.

RESULTS

There was a decrease in cystine, citrulline, and arginine; however, an increase in glutamine was found in all relaxed compared to natural hair. Cystine levels (milligram per gram amino acid nitrogen) were similar in natural proximal and distal hair: 14 mg/g (range, 4-15 mg/g) versus 14 mg/g (range, 12-15 mg/g); P = .139. In asymptomatic relaxed hair, cystine levels were higher in less frequently relaxed samples proximal to scalp: 7.5 mg/g (5.6-12) versus 3.3 mg/g (1.3-9.2); P = .005. Cystine levels in distal asymptomatic relaxed and symptomatic relaxed hair were similar to each other and to those in the genetic hair fragility disease trichothiodystrophy.

LIMITATIONS

It was not possible to analyze lye and no-lye 'relaxers' separately.

CONCLUSIONS

'Relaxers' are associated with reduced cystine consistent with fragile damaged hair. A decrease in citrulline and glutamine has been associated with inflammation; prospective studies are needed to investigate whether or how 'relaxers' induce inflammation.

Trichothiodystrophy with dysmyelination and central osteosclerosis

Trichothiodystrophy (TTD) is a rare group of autosomal recessive disorders of DNA repair unified by the presence of sulfur-deficient brittle hair. We report a 3-year-old boy with classic clinical features of TTD, including ichthyosis, alopecia, developmental delay, and tiger-tail banding of the hair shaft on polarizing microscopy. Brain MR imaging showed both diffuse dysmyelination and osteosclerosis, findings that, in combination, may be specific for TTD.

Trichothiodystrophy view from the molecular basis of DNA repair/transcription factor TFIIH

Trichothiodystrophy (TTD) is a rare autosomal recessive disorder characterized by brittle hair and also associated with various systemic symptoms. Approximately half of TTD patients exhibit photosensitivity, resulting from the defect in the nucleotide excision repair. Photosensitive TTD is due to mutations in three genes encoding XPB, XPD and p8/TTDA subunits of the DNA repair/transcription factor TFIIH. Mutations in these subunits disturb either the catalytic and/or the regulatory activity of the two XPB, XPD helicase/ATPases and consequently are defective in both, DNA repair and transcription. Moreover, mutations in any of these three TFIIH subunits also disturb the overall architecture of the TFIIH complex and its ability to transactivate certain nuclear receptor-responsive genes, explaining in part, some of the TTD phenotypes.

Disorders of nucleotide excision repair: the genetic and molecular basis of heterogeneity

Mutations in genes on the nucleotide excision repair pathway are associated with diseases, such as xeroderma pigmentosum, Cockayne syndrome and trichothiodystrophy, that involve skin cancer and developmental and neurological symptoms. These mutations cause the defective repair of damaged DNA and increased transcription arrest but, except for skin cancer, the links between repair and disease have not been obvious. Widely different clinical syndromes seem to result from mutations in the same gene, even when the mutations result in complete loss of function. The mapping of mutations in recently solved protein structures has begun to clarify the links between the molecular defects and phenotypes, but the identification of additional sources of clinical variability is still necessary.

From the rarest to the most common: insights from progeroid syndromes into skin cancer and aging

Despite their rarity, diseases of premature aging, or "progeroid" syndromes, have provided important insights into basic mechanisms that may underlie cancer and normal aging. In this review, we highlight these recent developments in Hutchinson-Gilford progeria syndrome (HGPS), Werner syndrome, Bloom syndrome, Cockayne syndrome, trichothiodystrophy, ataxia-telangiectasia, Rothmund-Thomson syndrome, and xeroderma pigmentosum. Though they are caused by different mutations in various genes and often result in quite disparate phenotypes, deciphering the molecular bases of these conditions has served to highlight their underlying basic similarities. Studies of progeroid syndromes, particularly HGPS, the most dramatic form of premature aging, have contributed to our knowledge of fundamental processes of importance to skin biology, including DNA transcription, replication, and repair, genome instability, cellular senescence, and stem-cell differentiation.

Polarized Raman microspectroscopy on intact human hair

Polarization-resolved Raman microspectroscopy with near-infrared laser excitation was applied to intact human hair in order to non-invasively investigate the conformation and orientation of the polypeptide chains. By varying the orientation of the hair shaft relative to the polarization directions of the laser/analyzer, a set of four polarized Raman spectra is obtained; this allows to simultaneously determine both the secondary structure of hair proteins and the orientation of the polypeptide strands relative to the axis of the hair shaft. For the amide I band, results from a quantitative analysis of the polarized Raman spectra are compared with theoretically expected values for fibers with uniaxial symmetry. Based on the polarization behavior of the amide I band and further vibrational bands, a partial ordering of alpha-helical polypeptide strands parallel to the hair shaft can be concluded. We suggest that this microspectroscopic approach may be used for human hair diagnostics by detecting structural or orientational alterations of keratins.

Trichothiodystrophy: a systematic review of 112 published cases characterises a wide spectrum of clinical manifestations

Trichothiodystrophy (TTD) is a rare, autosomal recessive disease, characterised by brittle, sulfur deficient hair and multisystem abnormalities. A systematic literature review identified 112 patients ranging from 12 weeks to 47 years of age (median 6 years). In addition to hair abnormalities, common features reported were developmental delay/intellectual impairment (86%), short stature (73%), ichthyosis (65%), abnormal characteristics at birth (55%), ocular abnormalities (51%), infections (46%), photosensitivity (42%), maternal pregnancy complications (28%) and defective DNA repair (37%). There was high mortality, with 19 deaths under the age of 10 years (13 infection related), which is 20-fold higher compared to the US population. The spectrum of clinical features varied from mild disease with only hair involvement to severe disease with profound developmental defects, recurrent infections and a high mortality at a young age. Abnormal characteristics at birth and pregnancy complications, unrecognised but common features of TTD, suggest a role for DNA repair genes in normal fetal development.

Characterization of the structural and molecular defects in fibres and follicles of the Merino felting lustre mutant

The felting lustre (FL) mutation found in Merino sheep results in a fleece that has a lustrous appearance and readily felts. This phenotype was described 50 years ago to result from the mutation of a single gene, but the molecular and cellular changes in the wool are not well understood. In this study, follicle and fibre material of FL mutant (n = 3) and normal control (n = 5) Merino ewes was compared using histological analysis, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), real-time polymerase chain reaction (qPCR) and electron microscopy [scanning electron microscopy (SEM) and transmission electron microscopy (TEM)]. Histological examination suggested that follicle structure in FL mutants is essentially normal, while SDS-PAGE analysis found that some low molecular weight keratin-associated proteins (KAP) were present at much lower levels in FL wool. Examination of transcript prevalence revealed that the KAP6.1, KAP7 and KAP8 genes in FL mutant follicles are downregulated, while the KAP2.12 and KAP4.2 genes are upregulated. TEM analysis indicated that there is only one type of cortical cell, the paracortical cell, in the fibre of FL mutants, while there are paracortical and orthocortical cells in fibres of normal Merino sheep. In contrast, SEM suggested the surface topography of FL wool fibres is normal. The evidence presented here strongly suggests that the properties of FL wool can be ascribed, at least in part, to the lower content of high glycine/tyrosine proteins and the reduction in orthocortical cells in mutant wool fibres.

Trichothiodystrophy-like hair abnormalities in a child with keratitis ichthyosis deafness syndrome

Keratitis ichthyosis deafness syndrome is a rare congenital ectodermal disorder. It appears to be genetically heterogeneous and may be caused by mutations in the connexin 26 (Cx26) gene (GJB2) or in the connexin 30 gene. It is characterized by the association of ichthyosis-like skin lesions, hearing loss, and vascularizing keratitis. We report the clinical and molecular findings in a 5-year-old girl with keratitis ichthyosis deafness syndrome. DNA sequencing in our patient revealed a p.Ser17Phe mutation in GJB2. Besides the typical clinical features of keratitis ichthyosis deafness syndrome, a peculiar intriguing finding not previously described in the literature in this condition was that polarizing light microscopy of the scalp hair in our patient revealed striking bright and dark bands as seen in trichothiodystrophy. Amino acid analysis of the hair sample also disclosed a reduced cysteine index. We emphasize that it would be of great benefit to examine hair shafts in other patients with keratitis ichthyosis deafness syndrome for trichothiodystrophy-like abnormalities.

Xeroderma pigmentosum, trichothiodystrophy and Cockayne syndrome: a complex genotype-phenotype relationship

Patients with the rare genetic disorders, xeroderma pigmentosum (XP), trichothiodystrophy (TTD) and Cockayne syndrome (CS) have defects in DNA nucleotide excision repair (NER). The NER pathway involves at least 28 genes. Three NER genes are also part of the basal transcription factor, TFIIH. Mutations in 11 NER genes have been associated with clinical diseases with at least eight overlapping phenotypes. The clinical features of these patients have some similarities but also have marked differences. NER is involved in protection against sunlight-induced DNA damage. While XP patients have 1000-fold increase in susceptibility to skin cancer, TTD and CS patients have normal skin cancer risk. Several of the genes involved in NER also affect somatic growth and development. Some patients have short stature and immature sexual development. TTD patients have sulfur deficient brittle hair. Progressive sensorineural deafness is an early feature of XP and CS. Many of these clinical diseases are associated with developmental delay and progressive neurological degeneration. The main neuropathology of XP is a primary neuronal degeneration. In contrast, CS and TTD patients have reduced myelination of the brain. These complex neurological abnormalities are not related to sunlight exposure but may be caused by developmental defects as well as faulty repair of DNA damage to neuronal cells induced by oxidative metabolism or other endogenous processes.