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$Title{Dyskeratosis Congenita}
$Subject{Dyskeratosis Congenita DKC Dyschromatosis Universalis Hereditaria
Dyskeratosis Congenita Autosomal Recessive Type Dyskeratosis Congenita
Scoggins Type Dyskeratosis Congenita Syndrome Zinsser-Cole-Engman Syndrome
Ectodermal Dysplasias Fanconi's Anemia}
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Copyright (C) 1992 National Organization for Rare Disorders, Inc.

896:
Dyskeratosis Congenita

** IMPORTANT **
It is possible that the main title of the article (Dyskeratosis
Congenita) is not the name you expected.  Please check the SYNONYMS listing
to find the alternate name and disorder subdivisions covered by this article.

Synonyms

     DKC
     Dyschromatosis Universalis Hereditaria
     Dyskeratosis Congenita, Autosomal Recessive Type
     Dyskeratosis Congenita, Scoggins Type
     Dyskeratosis Congenita Syndrome
     Zinsser-Cole-Engman Syndrome

Information on the following diseases can be found in the Related
Disorders section of this report:

     Ectodermal Dysplasias
     Fanconi's Anemia

General Discussion

** REMINDER **
The Information contained in the Rare Disease Database is provided for
educational purposes only.  It should not be used for diagnostic or treatment
purposes.  If you wish to obtain more information about this disorder, please
contact your personal physician and/or the agencies listed in the "Resources"
section of this report.

Dyskeratosis Congenita is a rare disorder in which three groups of
symptoms occur:  darkening and/or unusual absence of skin color
(hyper/hypopigmentation); progressive nail dystrophy; and slowly changing
characteristics of mucous membranes (leukoplakia) in the anus, urethra, lips,
mouth and/or eye.

Other symptoms found in some patients with this syndrome may be reduction
in red and white blood cells and platelets (pancytopenia), overgrowth of skin
on the palms of the hands and soles of the feet, excessive sweating of the
palms and soles, sparse or absent hair, fragile bones, underdeveloped testes,
and dental abnormalities.  Dyskeratosis Congenita is more prevalent among
males then females and an X-linked recessive inheritance is the most common
form although cases of autosomal recessive and autosomal dominant inheritance
have been recorded.  This disorder has also occurred sporadically (no known
cause) in a significant number of cases.

Symptoms

The main symptoms of Dyskeratosis Congenita are:

1.  Hyper and Hypopigmentation - Hyperpigmentation in Dyskeratosis
Congenita has a net like pattern of distribution that is brownish-grey in
color.  Hypopigmentation is a lack of skin color that is intermixed.  These
skin discolorations may be present at birth but usually are progressive and
appear later.

2.  Progressive nail dystrophy may lead to loss of nails on the fingers
or toes.  This is visually not present at birth.

3.  Mucosal leukoplakia - a slowly developing change in normal tissue of
a mucous membrane.  This condition may be found in the mucous membranes of
the anus, urethra, lips, mouth and/or eyes.  This condition should be watched
closely and the leukoplakic lesions removed before they can become malignant.

The following conditions are often, but not always, present in patients
with Dyskeratosis Congenita:

4.  Pancytopenia - a reduction in the normal number of red and white
blood cells and platelets caused by bone marrow failure.

5.  Hyperkeratosis - the overgrowth of skin on the palms of the hands and
the soles of the feet.  This condition often causes a lack of finger and foot
prints.

6.  Hyperhidrosis - excessive sweating of the palms of the hands and the
soles of the feet.

7.  Atresia of the lacrimal puncta - absence of the tiny opening in the
edge of each eyelid that drains the tears.  This condition causes chronic
tearing.

The following conditions are sometimes associated with Dyskeratosis
Congenita and have been found in some patients with this disorder:

8.  Alopecia - absence of hair from skin areas where it is normally
present.  The hair is often fine and sparse and there may be premature
graying.

9.  Dental abnormalities -  displacement of teeth from a normal position
in the dental arch.  Teeth may also be lost at an early age.

10.  Osteoporosis - a decrease in bone mass.  Patients with Dyskeratosis
Congenita may also have a fragile build and a slow growth pattern.

11.  Testicular atrophy - incomplete or underdeveloped testes.  The penis
may also be underdeveloped.

12.  Thrombocytopenia - an abnormally small number of platelets (the part
of the blood that helps in clotting) in the circulating blood.

13.  Microcephaly - a small circumference of the head.


14.  Mental retardation or reduced intelligence.

15.  Cirrhosis of the liver - a long-term disease of the liver in which
the liver becomes covered with fiberlike tissue and hardens - also called
nutmeg-like cirrhosis.

16.  Dysphasia - difficulty in swallowing.

17.  Acrocyanosis - hands and/or feet that are a blue color, cold and
sweaty.  This is caused by spasms of the blood vessels and usually occurs
when the patient is cold or under stress.

18.  Cataracts - a disease of the eye in which the lens loses it's
clearness.  A grey-white film can be seen in the lens.  (For more information
on this disorder choose "Cataracts" as your search term in the Rare Disease
Database).

Causes

Most cases of Dyskeratosis Congenita have an X-linked recessive inheritance
although cases have been reported of autosomal recessive and autosomal
dominant inheritance.  A significant number of cases have also occurred
sporadically.

Human traits, including the classic genetic diseases, are the product of
the interaction of two genes, one received from the father and one from the
mother.

In dominant disorders a single copy of the disease gene (received from
either the mother or father) will be expressed "dominating" the other normal
gene and resulting in the appearance of the disease.  The risk of
transmitting the disorder from affected parent to offspring is fifty percent
for each pregnancy regardless of the sex of the resulting child.

In recessive disorders, the condition does not appear unless a person
inherits the same defective gene for the same trait from each parent.  If one
receives one normal gene and one gene for the disease, the person will be a
carrier for the disease, but usually will not show symptoms.  The risk of
transmitting the disease to the children of a couple, both of whom are
carriers for a recessive disorder, is twenty-five percent.  Fifty percent of
their children will be carriers, but healthy as described above.  Twenty-five
percent of their children will receive both normal genes, one from each
parent, and will be genetically normal.

X-linked recessive disorders are conditions which are coded on the X
chromosome.  Females have two X chromosomes, but males have one X chromosome
and one Y chromosome.  Therefore, in females, disease traits on the X
chromosome can be masked by the normal gene on the other X chromosome.  Since
males only have one X chromosome, if they inherit a gene for a disease
present on the X, it will be expressed.  Men with X-linked disorders transmit
the gene to all their daughters, who are carriers, but never to their sons.
Women who are carriers of an X-linked disorder have a fifty percent risk of
transmitting the carrier condition to their daughters, and a fifty percent
risk of transmitting the disease to their sons.

Dyskeratosis Congenita has been mapped to the Xq27-q28 gene.

Affected Population

Dyskeratosis Congenita affects males most often, with the ratio of affected
males to females being M10:F1.  This disorder is usually detected between the
ages of five and fifteen although skin and nail abnormalities may be present
at birth.  There have been only 120 cases of Dyskeratosis Congenita reported
and the disease has occurred in all races.

Related Disorders

Symptoms of the following disorders can be similar to those of Dyskeratosis
Congenita.  Comparisons may be useful for a differential diagnosis:

Ectodermal Dysplasias are a group of hereditary, non-progressive
syndromes in which the affected tissue derives primarily from the ectodermal
germ layer.  The skin, it's derivatives, and some other organs are involved.
A predisposition to respiratory infections, due to a somewhat depressed
immune system and to defective mucous glands in parts of the respiratory
tract, is the most life threatening characteristic of this group of
disorders.  Symptoms include eczema, poorly functioning sweat glands, sparse
or absent hair follicles, abnormal hair, disfigured nails, and difficulties
with the nasal passages and ear canals.  Skin is satiny smooth, prone to
rashes, and slow to heal.  (For more information on this disorder choose
"Ectodermal Dysplasias" as your search term in the Rare Disease Database).

Fanconi's Anemia is a rare form of familial aplastic anemia (a disease of
the bone marrow) found chiefly in children.  It is characterized by bone
marrow abnormalities, a small circumference of the head, retarded sexual
development and brown pigmentation of the skin.  Complications such as
pneumonia and meningitis, hemorrhages and leukemia may occur.  (For more
information on this disorder choose "Anemia, Fanconi's" as your search term
in the Rare Disease Database).

Therapies:  Standard

Treatment of Dyskeratosis Congenita is symptomatic and supportive.
Leukoplakic lesions should be surgically removed to prevent malignancy.
Dental abnormalities will require dental intervention.

Genetic counseling may be of benefit for patients and their families.

Therapies:  Investigational

Research on birth defects and their causes is ongoing.  The National
Institutes of Health (NIH) is sponsoring the Human Genome Project which is
aimed at mapping every gene in the human body and learning why they sometimes
malfunction.  It is hoped that this new knowledge will lead to prevention and
treatment of genetic disorders in the future.

This disease entry is based upon medical information available through
February 1992.  Since NORD's resources are limited, it is not possible to
keep every entry in the Rare Disease Database completely current and
accurate.  Please check with the agencies listed in the Resources section for
the most current information about this disorder.

Resources

For more information on Dyskeratosis Congenita, please contact:

     National Organization for Rare Disorders
     P.O. Box 8923
     New Fairfield, CT  06812-1783
     [phone]

     National Foundation for Ectodermal Dysplasias
     219 E. Main St.
     Mascoutah, IL  62258
     [phone]

     NIH/National Institute of Child Health and Human Development (NICHD)
     9000 Rockville Pike
     Bethesda, MD  20892
     [phone]

     NIH/National Heart, Lung and Blood Institute (NHLBI)
     9000 Rockville Pike
     Bethesda, MD  20892
     [phone]

For Genetic Information and Genetic Counseling Referrals:

     March of Dimes Birth Defects Foundation
     1275 Mamaroneck Avenue
     White Plains, NY 10605
     [phone]

     Alliance of Genetic Support Groups
     35 Wisconsin Circle, Suite 440
     Chevy Chase, MD  20815
     (800) 336-GENE
     [phone]

References

MENDELIAN INHERITANCE IN MAN, 9th Ed.:  Victor A. McKusick, Editor:  Johns
Hopkins University Press, 1990.  Pp. 275, 1154, 1586.

SMITH'S RECOGNIZABLE PATTERNS OF HUMAN MALFORMATION, 4th Ed.:  Kenneth L.
Jones, M.D., Editor; W.B. Saunders Co., 1988.  Pp. 474.

BIRTH DEFECTS ENCYCLOPEDIA, Mary Louise Buyse, M.D., Editor-In-Chief;
Blackwell Scientific Publications, 1990.  Pp. 567-68.

DIAGNOSTIC RECOGNITION OF GENETIC DISEASES, William Nyhan, Nadia O
Sakati, Editors; Lea & Febiger, 1987.  Pp. 600, 672.

ENHANCED G2 CHROMATID RADIOSENSITIVITY TO DYSKERATOSIS CONGENITA
FIBROBLASTS:  D.M. DeBauche, et al.; Am J Hum Genet (February, 1990, issue
46(2)).  Pp. 350-7.

DYSKERATOSIS CONGENITA:  REPORT OF A CASE AND REVIEW OF THE LITERATURE:
G.R. Ogden, et al.; Oral Surg Oral Med Oral Pathol (May 1988, issue 65(5)).
Pp. 586-91.

ETIOLOGIC HETEROGENEITY IN DYSKERATOSIS CONGENITA:  G.S. Pai, et al.;  Am
J Med Genet (January 1989, issue 32(1)).  Pp. 63-6.