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Genetic Screening for Filaggrin Mutation in Atopic Dermatitis and Ichthyosis Vulgaris in the African American Population

Genetic Screening for Filaggrin Mutation in Atopic Dermatitis and Ichthyosis Vulgaris in the African American Population

Status
Completed
Phases
NA
Study type
Interventional
Source
ClinicalTrials.gov
Registry ID
NCT01016106
Enrollment
35
Registered
2009-11-18
Start date
2010-06-30
Completion date
2011-09-30
Last updated
2015-05-01

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Atopic Dermatitis, Ichthyosis Vulgaris

Keywords

eczema, atopic dermatitis, dry skin, ichthyosis vulgaris

Brief summary

The investigators' primary objective is to identify common and rare mutations in the filaggrin gene in African American patients with a diagnosis of atopic dermatitis and ichthyosis vulgaris. Atopic dermatitis, or eczema, is a common, chronic, relapsing and remitting problem in many children and affects 10-20% of the pediatric population. Itch is a predominant feature of this disease and is quite disruptive to daily activities of life. In addition to itch, it is characterized by markedly dry skin, small red bumps that may have fluid. Ichthyosis vulgaris is characterized by extremely dry, scaly skin with a fine white scale and increased amounts of lines noted on the palms. Filaggrin is a protein that is essential for the skin to function properly as a barrier and found to be mutated in some European patients with ichthyosis vulgaris and atopic dermatitis. This association has not been looked at in the African American population. Genomic DNA (gDNA) will be purified from buccal swabs using commercially available kits and analyzed.

Detailed description

Genetic screening and molecular dermatology allow physicians and scientists to screen populations who manifest a specific genetic disorder of skin, hair or nails and to study animal models for experiment-induced dermatopathology, diseases, and treatments. The purpose of such screening is to identify the gene(s) involved in eliciting the phenotypic characteristics that we as clinicians identify for diagnosis and treatment of said disease(s). The field of genetics in dermatology has progressed immensely in the last 20 years and has strongly influenced the practice of dermatology. Most known single gene disorders, such as epidermoloysis bullosa, have been mapped to a particular chromosomal region and in many cases, the causative genes have been identified. However, more common diseases that are polygenic in origin such as atopic dermatitis remain a challenge to decipher. In addition, there still remain several monogenic disorders in which the underlying genetic basis is unclear. In some cases, genetic analysis can be performed by sequencing entire genes or gene regions, or screening for specific common mutations. In the Japanese and some of the European populations, several researchers have been able to find an association between people with atopic dermatitis and ichythosis vulgaris and the filaggrin gene. Atopic dermatitis, or ezcema, is a common, chronic, relapsing and remitting problem in many children and affects 10-20% of the pediatric population. Atopic dermatitis is often called the itch that rashes, since itch is a predominant feature of this disease and is quite disruptive to daily activities of life. In addition to itch, it is characterized by markedly dry skin, small red bumps that may have fluid. Though treatments are available to help the rash resolve and to help with itch, this disease will continue to appear when treatments are stopped and often become infected. Ichythosis vulgaris is quite prevalent, an estimated 1 in 250 persons are affected. It is characterized by extremely dry, scaly skin with a fine white scale and increased amounts of lines noted on the palms. Ichythosis vulgaris is thought to happen due to a combination of excess production of one of the layers of the skin and abnormal skin shedding. Filaggrin is a protein that is essential for the skin to function properly as a barrier. It was initially thought to be one of the genes responsible for causing atopic dermatitis in 2006 after it was identified as the causal mutation in ichthyosis vulgaris. This association has been extensively studied in the European population and to a lesser extent in the Japanese population; however, has not been looked at in the African American population These new insights may help lead to future targeted therapy for these two extraordinarily common skin disorders. General clinical applications of methods for diagnosis may include histological tissue examination, laboratory-based specimen analysis, and physical examination. However, although useful, all of these methods are limited to the identification of the phenotypic expression of the genetic abnormality. Conversely, genetic screening of tissue (collected via buccal swabs) enables the clinician and scientist to have access to a more finite method of diagnosis, treatment, and prevention options. Such methods of testing are particularly appealing for use in disorders in which the exact basis of the disease is unknown, as is the case of atopic dermatitis and ichythosis vulgaris in the African American population. Thus, genetic screening in the field of dermatology remains an important research agenda and is the focus of this proposal. This study allows for the collection of genetic material from patients seen in the dermatology clinic at Ann & Robert H Lurie Children's Hospital of Chicago.

Interventions

During a single visit, a subject data collection form will be completed and DNA will be extracted from samples (buccal swabs) and then analyzed at IBT laboratories in Lenexa, Kansas.

Sponsors

Northwestern University
Lead SponsorOTHER
ViraCor Laboratories
CollaboratorINDUSTRY

Study design

Allocation
NON_RANDOMIZED
Intervention model
SINGLE_GROUP
Primary purpose
DIAGNOSTIC
Masking
DOUBLE (Subject, Outcomes Assessor)

Eligibility

Sex/Gender
ALL
Age
6 Months to No maximum
Healthy volunteers
Yes

Inclusion criteria

* Age greater than 6 months * Affected subjects: Must be African American and have a diagnosis of both atopic dermatitis or eczema as well as ichthyosis vulgaris * Control subjects: Must be healthy African American subjects * Must be willing to not apply emollients for 24 hours prior to visit.

Exclusion criteria

* Systemic illness * Control subjects: Must not have a family history of atopy (including asthma, seasonal allergies or hay fever or allergic rhinitis, or eczema or atopic dermatitis) * Control subjects: Must never have been given a diagnosis of eczema or atopic dermatitis * Control subjects: Must not have excessively dry skin * Must not be of Hispanic ethnicity

Design outcomes

Primary

MeasureTime frameDescription
Heterozygous for Filaggrin (FLG) Null Mutations1 monthBuccal swab samples were obtained from each subject. Deoxyribonucleic acid (DNA) was purified from buccal swabs (IsoHelix Swabs, BocaScientific, Boca Raton, FL) and quantified by ultraviolet spectrophotometry. Purified genomic DNA and controls were amplified by polymerase chain reaction (PCR) from three different regions of FLG exon 3 with three primer sets. PCR products were analyzed by electrophoresis, purified (Qiaquick, Qiagen, Valencia, CA), and subjected to duplicate cycle sequencing reactions using ABI BigDye v3.1 reagents (Applied Biosystems, Carlsbad, CA). Labeled sequencing products were purified for capillary electrophoresis (ABI3730 or ABI3130 sequencer with POP7 polymer), and sequence results were examined using ABI SeqScape software. All nucleotide changes were noted, including 30 single nucleotide polymorphism (SNPs) in the population tested, the most common of which were coding changes at T454A, H2507Q, and G2545R, and silent change at nucleotide t2508c.

Countries

United States

Participant flow

Participants by arm

ArmCount
African American (AA) Control Subjects
African American subjects with no personal or family history of ichthyosis vulgaris or atopy. Buccal swabs were obtained from each subject for DNA analysis.
17
AA Subjects With Atopic Dermatitis and Ichthyosis Vulgaris
African American subjects with a diagnosis of atopic dermatitis and ichthyosis vulgaris. Buccal swabs were obtained from each subject for DNA analysis.
18
Total35

Baseline characteristics

CharacteristicAfrican American (AA) Control SubjectsAA Subjects With Atopic Dermatitis and Ichthyosis VulgarisTotal
Age, Categorical
<=18 years
2 Participants17 Participants19 Participants
Age, Categorical
>=65 years
7 Participants0 Participants7 Participants
Age, Categorical
Between 18 and 65 years
8 Participants1 Participants9 Participants
Region of Enrollment
United States
17 participants18 participants35 participants
Sex: Female, Male
Female
10 Participants12 Participants22 Participants
Sex: Female, Male
Male
7 Participants6 Participants13 Participants

Adverse events

Event typeEG000
affected / at risk
EG001
affected / at risk
deaths
Total, all-cause mortality
— / —— / —
other
Total, other adverse events
0 / 170 / 18
serious
Total, serious adverse events
0 / 170 / 18

Outcome results

Primary

Heterozygous for Filaggrin (FLG) Null Mutations

Buccal swab samples were obtained from each subject. Deoxyribonucleic acid (DNA) was purified from buccal swabs (IsoHelix Swabs, BocaScientific, Boca Raton, FL) and quantified by ultraviolet spectrophotometry. Purified genomic DNA and controls were amplified by polymerase chain reaction (PCR) from three different regions of FLG exon 3 with three primer sets. PCR products were analyzed by electrophoresis, purified (Qiaquick, Qiagen, Valencia, CA), and subjected to duplicate cycle sequencing reactions using ABI BigDye v3.1 reagents (Applied Biosystems, Carlsbad, CA). Labeled sequencing products were purified for capillary electrophoresis (ABI3730 or ABI3130 sequencer with POP7 polymer), and sequence results were examined using ABI SeqScape software. All nucleotide changes were noted, including 30 single nucleotide polymorphism (SNPs) in the population tested, the most common of which were coding changes at T454A, H2507Q, and G2545R, and silent change at nucleotide t2508c.

Time frame: 1 month

ArmMeasureValue (NUMBER)
African American (AA) Control SubjectsHeterozygous for Filaggrin (FLG) Null Mutations1 participants
AA Subjects With Atopic Dermatitis and Ichthyosis VulgarisHeterozygous for Filaggrin (FLG) Null Mutations4 participants

Source: ClinicalTrials.gov · Data processed: Feb 4, 2026