Down syndrome
Down syndrome, also known as trisomy 21, is a genetic disorder caused by the presence of an extra copy of chromosome 21. Typically, each cell in the human body contains 23 pairs of chromosomes, but individuals with Down syndrome have a full or partial extra copy of chromosome 21.
This additional genetic material affects the development of the individual, leading to characteristic physical features, intellectual disabilities, and various health issues. Some common physical features associated with Down syndrome include a flat facial profile, almond-shaped eyes that slant upwards, a small nose and ears, a protruding tongue, and a short stature.
Intellectual disabilities range from mild to moderate, and individuals with Down syndrome may experience delays in cognitive development, speech and language development, and motor skills.
Autism
Autism, also known as Autism Spectrum Disorder (ASD), is a neurodevelopmental disorder that affects social interaction, communication skills, and behavior. It’s called a “spectrum” disorder because it manifests differently in each individual, with a wide range of symptoms and severity levels.
Some common characteristics of autism include difficulties in social interaction, such as challenges in understanding and responding to social cues, difficulty in forming relationships, and a preference for routines and repetitive behaviors. Communication difficulties can range from delayed language development to difficulty understanding non-verbal communication cues like gestures and facial expressions.
As of my last update in January 2022, reliable global data on the gender percentage of autism diagnoses remains somewhat limited and varies depending on the source and methodology of the study. However, historically, autism has been diagnosed more frequently in males than females, leading to the widely cited statistic of a 4:1 male-to-female ratio or even higher.
