Sudden infant death with dysgenesis of the testes syndrome

(often shortened to SIDDT)

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What is SIDDT?

Sudden infant death with dysgenesis of the testes syndrome (SIDDT) is a rare condition that is fatal in the first year of life; its major features include abnormalities of the reproductive system in males, feeding difficulties, and breathing problems.

Infants with SIDDT who are genetically male, with one X chromosome and one Y chromosome in each cell, have underdeveloped or abnormal testes. They may also have external genitalia that appear female or that do not look clearly male or clearly female (ambiguous genitalia). In affected infants who are genetically female, with two X chromosomes in each cell, development of the internal and external reproductive organs is normal.

SIDDT is associated with abnormal development of the brain, particularly the brainstem, which is the part of the brain that is connected to the spinal cord. The brainstem regulates many basic body functions, including heart rate, breathing, eating, and sleeping. It also relays information about movement and the senses between the brain and the rest of the body. Many features of SIDDT appear to be related to brainstem malfunction, including a slow or uneven heart rate, abnormal breathing patterns, difficulty controlling body temperature, unusual tongue and eye movements, abnormal reflexes, seizures, and feeding difficulties. Affected infants also have an unusual cry that has been described as similar to the bleating of a goat, which is probably a result of abnormal nerve connections between the brain and the voicebox (larynx).

The brainstem abnormalities lead to death in the first year of life, when affected infants suddenly stop breathing or their heart stops beating (cardiorespiratory arrest).

How common is SIDDT?

SIDDT has been diagnosed in more than 20 infants from a single Old Order Amish community in Pennsylvania. The condition has not been reported outside this community.

What genes are related to SIDDT?

A single mutation in the TSPYL1 gene has caused all identified cases of SIDDT. This gene provides instructions for making a protein called TSPY-like 1, whose function is unknown. Based on its role in SIDDT, researchers propose that TSPY-like 1 is involved in the development of the male reproductive system and the brain.

The TSPYL1 gene mutation that causes SIDDT eliminates the function of TSPY-like 1. The loss of this protein's function appears to cause the major features of the disorder by disrupting the normal development of the male reproductive system and the brain, particularly the brainstem.

Research findings suggest that mutations in the TSPYL1 gene are not associated with sudden infant death syndrome (SIDS) in the general population. SIDS is a major cause of death in children younger than 1 year.

How do people inherit SIDDT?

This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition.

Where can I find information about diagnosis or management of SIDDT?

These resources address the diagnosis or management of SIDDT and may include treatment providers.

You might also find information on the diagnosis or management of SIDDT in Educational resourcesand Patient support.

General information about the diagnosis and management of genetic conditions is available in the Handbook. Read more about genetic testing, particularly the difference between clinical tests and research tests.

To locate a healthcare provider, see How can I find a genetics professional in my area? in the Handbook.

Where can I find additional information about SIDDT?

You may find the following resources about SIDDT helpful. These materials are written for the general public.

MedlinePlus - Health information
Educational resources - Information pages (3 links)
Patient support - For patients and families (3 links)

You may also be interested in these resources, which are designed for healthcare professionals and researchers.

Genetic Testing Registry - Repository of genetic test information (1 link)
PubMed - Recent literature
OMIM - Genetic disorder catalog

What if I still have specific questions about SIDDT?

Ask the Genetic and Rare Diseases Information Center

Where can I find general information about genetic conditions?

The Handbook provides basic information about genetics in clear language.

These links provide additional genetics resources that may be useful.

What glossary definitions help with understanding SIDDT?

autonomic nervous system ; autosomal ; autosomal recessive ; brainstem ; cell ; chromosome ;dysgenesis ; gene ; genitalia ; inherited ; mutation ; nervous system ; population ; protein ; recessive ;syndrome ; testes

You may find definitions for these and many other terms in the Genetics Home Reference Glossary.

References (4 links)

The resources on this site should not be used as a substitute for professional medical care or advice. Users seeking information about a personal genetic disease, syndrome, or condition should consult with a qualified healthcare professional. See How can I find a genetics professional in my area? in the Handbook.