Autism and Williams syndrome are genetically based neurodevelopmental disorders that present strikingly different social phenotypes. Autism involves fundamental impairments in social reciprocity and communication, whereas people with Williams syndrome are highly sociable and engaging.

However, there are many important differences between the two disorders. Noonan syndrome affects both males and females, and there is a normal chromosomal makeup (karyotype). Only females are affected by Turner syndrome, which is characterized by abnormalities affecting the X chromosome.

Learning problems are common in children with Williams syndrome. They range from mild to severe. Children are slower to walk, talk, and gain new skills compared to other children their age. They may have a learning disorder such as attention-deficit hyperactivity disorder (ADHD).

This disorder is usually observed before the child reaches the age of 4 years. In some cases, it may not be diagnosed until the child starts school.

There is no cure for Williams syndrome, nor is there a standard course of treatment.

Williams syndrome and Down syndrome are both chromosomal disorders affecting people from birth. However, Williams syndrome is caused by a missing chromosome, while Down syndrome is caused by an extra chromosome.

There is no known way to prevent the genetic problem that causes Williams syndrome.

A team of scientists led by the National Institutes of Health has now found in Williams syndrome cases changes in the connectivity and volume of gray matter in a brain region called the anterior insula (AI), which is thought to control emotion and personality.

Because some cases of Noonan syndrome occur spontaneously, there’s no known way to prevent it. However, if you have a family history of this syndrome, talk to your doctor about the benefits of genetic counseling before you have children. Noonan syndrome can be detected with molecular genetic testing.

Before your baby is born, your doctor might consider that he has Noonan syndrome if a pregnancy ultrasound shows: Extra amniotic fluid around your baby in the amniotic sac. A cluster of cysts in your baby’s neck. Problems with their heart structure or other structural problems.

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In 2001, Tartaglia and his co-workers found a mutation in the protein tyrosine phosphatase non–receptor type 11 gene (PTPN11), which was the first molecular cause of Noonan syndrome. Observations that PTPN11 occupied the critical region of NS1 enabled this discovery.

Genetic testing of patient NM included a microarray which revealed a 3p duplication including the RAF1 gene and a diagnosis of Noonan Syndrome was made.

Molecular genetic testing can confirm diagnosis in 70% of cases and has important implications for genetic counseling and management. Most patients with Noonan syndrome are intellectually normal as adults, but some may require multidisciplinary evaluation and regular follow-up care.

Microarray analysis may also detect large parts of a chromosome that are genetically identical. Having genetically identical chromosome parts could mean that a person’s parents are blood relatives or have a common ancestor.

Overall, microarray was successful in 98.8% of cases (4340 of 4391). The microarray analysis was performed on uncultured samples for 3860 (87.9%) of the 4391 participants.

A microarray is the recommended first line genetic test for developmental delay (DD), intellectual disability (ID) and autism spectrum disorders (ASD)*. CMA however, does not identify fragile X syndrome (FXS), a common cause of intellectual disability.

Spectrum’s newsletter. Blue chips: Microarrays are efficient and accurate at detecting autism variants, but are virtually unknown to most pediatricians and family practice doctors.

Microarray analyses cost as little as $100 per sample for standard gene-expression analysis and $300 per sample for more-complex analyses involving differentiation between variant splice forms, according to Affymetrix. (This estimate excludes extra fees from service providers.)