Seckel syndrome

Definition

Seckel syndrome is an extremely rare inherited disorder characterized by low birth weight, dwarfism, a very small head, mental retardation, and unusual characteristic facial features, including a "beak-like" protrusion of the nose, large eyes, a narrow face, low ears, and an unusually small jaw. Common signs also include abnormalities of bones in the arms and legs.

Description

Seckel syndrome is one of the microcephalic primordial dwarfism syndromes—a category of disorders characterized by profound growth delay. It is marked by dwarfism, a small head, developmental delay, and mental retardation. Abnormalities may also be found in the cardiovascular, hematopoietic, endocrine, and central nervous systems. Children with the disorder are often hyperactive and easily distracted; about half have IQs below 50. Individuals with Seckel syndrome are able to live for an extended period of time.

Seckel syndrome is also known as "bird-headed dwarfism," Seckel type dwarfism, and nanocephalic dwarfism. The disorder was named after Helmut G.P. Seckel, a German pediatrician who came to the United States in 1936. Dr. Seckel did not discover the syndrome but he authored a publication describing the disorder's symptoms based on two of his patients.

Genetic profile

Seckel syndrome displays an autosomal-recessive pattern of inheritance . This means that both parents of a child with the disorder carry a copy of the Seckel gene—but the parents appear entirely normal. When both parents carry a copy of the Seckel gene , their children face a one in four chance of developing the disorder.

Demographics

Seckel syndrome is extremely rare. Between 1960—the year that Dr. Seckel defined the disorder—and 1999, fewer than 60 cases were reported.

Signs and symptoms

Prenatal signs of Seckel syndrome include cranial abnormalities and growth delays (intrauterine growth retardation) resulting in low birth weight. Postnatal growth delays result in dwarfism. Other physical features associated with the disorder include a very small head (often more severely affected than even the height), abnormalities of bones in the arms and legs, malformation of the hips, a permanently bent fifth finger, failure of the testes to descend into the scrotum (for males) and unusual characteristic facial features, including a "beak-like" protrusion of the nose, large eyes, a narrow face, low ears, and an unusually small jaw. Children with the disorder not only have a small head but also a smaller brain, which leads to developmental delay and mental retardation. Seizures have also been reported.

Diagnosis

Several forms of primordial dwarfism exhibit characteristics similar to those of Seckel syndrome, and it can be challenging for physicians to differentiate true Seckel syndrome from other similar dwarfisms. Physicians do have a set of primary diagnostic criteria to follow—the criteria were first defined by Dr. Seckel in 1960 and later revised (1982) to prevent over-diagnosis of cases.

Most of the primary diagnostic features of Seckel syndrome, which include severe intrauterine growth restriction, a small head, characteristic "bird-like" facies, and mental retardation, are well suited for prenatal sonographic diagnosis. The use of ultrasound examinations to evaluate fetal growth and the careful evaluation of the fetal face and cranial anatomy have proven effective at detecting Seckel syndrome.

Treatment and management

There is no cure for Seckel syndrome. Certain medications may be prescribed to address other symptoms associated with the disorder.

Prognosis

Children affected with Seckel syndrome can live for an extended period of time, although they are often faced with profound mental and physical deficits.

Resources

ORGANIZATIONS

Human Growth Foundation. 997 Glen Cove Ave., Glen Head, NY 11545. (800) 451-6434. Fax: (516) 671-4055. <http://[email protected]>.

National Organization for Rare Disorders (NORD). PO Box 8923, New Fairfield, CT 06812-8923. (203) 746-6518 or (800) 999-6673. Fax: (203) 746-6481. <http://www.rarediseases.org>.

WEBSITES

Alderman, Victoria. "Seckel Syndrome: A Case Study of Prenatal Sonographic Diagnosis." OBGYN.net Ultrasound (electronic journal) May 1998. <http://www.obgyn.net/us/cotm/9805/cotm9805.htm>.

MacDonald, M.R., et al. "Microcephalic Primordial Proportionate Dwarfism, Seckel Syndrome, in a Patient with Deletion of 1q 22-1q 24.3." <http://www.faseb.org/ashg97/f6229.html>.

"Seckel Syndrome." Online Mendelian Inheritance in Man. <http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=210600>.

Michelle Lee Brandt