Holoprosencephaly in a Down syndrome child

Area of Science:

• Medical Genetics
• Developmental Biology
• Neurology

Background:

• Gross central nervous system (CNS) malformations are uncommon in Down syndrome (DS).
• Holoprosencephaly is a severe brain malformation with various known causes.
• The co-occurrence of DS and holoprosencephaly is exceedingly rare.

Purpose of the Study:

• To report the first documented association between trisomy 21 (Down syndrome) and holoprosencephaly.
• To investigate a potential causal relationship between these two conditions.
• To explore the implications for understanding developmental field complexes (DFCs).

Main Methods:

• Case report of an infant diagnosed with both trisomy 21 and holoprosencephaly.
• Anatomical comparison of the holoprosencephalic defect with known forms of the condition.
• Review of existing literature on CNS malformations in Down syndrome and holoprosencephaly.

Main Results:

• The study presents the first known instance of holoprosencephaly in an infant with Down syndrome.
• The observed holoprosencephalic defect shares anatomical similarities with other known etiologies.
• This association suggests a potential link rather than a coincidental occurrence.

Conclusions:

• A causal relationship between trisomy 21 and holoprosencephaly is presumed due to the low probability of chance concurrence.
• Holoprosencephaly may represent a causally nonspecific developmental field complex (DFC).
• The increased incidence of DFCs in Down syndrome could stem from reduced developmental homeostasis due to autosomal aneuploidy.