Witteveen-Kolk syndrome (WITKOS)

What is Witteveen-Kolk syndrome (WITKOS)?

Witteveen-Kolk syndrome is a rare neuro-developmental disorder.

The syndrome is characterized by developmental delay and intellectual disability. As well as by unique facial characteristics and a short stature.

The syndrome occurs in less than 1 in 1000000 people worldwide making it extremely rare. It affects males and females equally. Currently just 40 individuals in the world have been diagnosed with the syndrome.

The syndrome is also known as 15q24 Microdeletion syndrome.

What gene changes cause Witteveen-Kolk syndrome (WITKOS)?

The syndrome is caused when a small piece of chromosome 15 is deleted in each cell. It follows an autosomal dominant pattern of inheritance. Some cases of the syndrome are new mutations.

In the case of autosomal dominant inheritance just one parent is the carrier of the gene mutation, and they have a 50% chance of passing it onto each of their children. Syndromes inherited in an autosomal dominant inheritance are caused by just one copy of the gene mutation.

In some cases, a genetic syndrome may be the result of a de-novo mutation and the first case in a family. In this case, this is a new gene mutation which occurs during the reproductive process.

What are the main symptoms of Witteveen-Kolk syndrome (WITKOS)?

Global development delay and mild to severe intellectual disability, as well as delayed speech development are common features of the syndrome.

Physical characteristics of the condition include a short stature, weak muscle tone and loose joints. Unique facial features include a small head, small hands and feets, abnormalities in the digits of the hands and feet, a full lower lip, long philtrum, high hairline, widely set eyes, broad eyebrows and a broad nasal bridge.

Possible clinical traits/features:
Autism, Attention deficit hyperactivity disorder, Polyhydramnios, Abnormality of the thorax, Abnormality of the voice, Abnormal palate morphology, Abnormality of the outer ear, Aggressive behavior, Anisocoria, Arachnodactyly, Aplasia/Hypoplasia affecting the eye, Camptodactyly of toe, Wide nose, Wide nasal bridge, Cafe-au-lait spot, Abnormal eyebrow morphology, Epicanthus, Deeply set eye, Everted lower lip vermilion, Small for gestational age, Downslanted palpebral fissures, Dysplastic corpus callosum, Smooth philtrum, Flared nostrils, Facial asymmetry, External ear malformation, Feeding difficulties in infancy, Finger syndactyly, Conspicuously happy disposition, Coarse hair, Malformation of the heart and great vessels, Congenital diaphragmatic hernia, Cupped ear, Cryptorchidism, Displacement of the urethral meatus, Brachydactyly, Developmental regression, Deep plantar creases, Microcephaly, Thick lower lip vermilion, Short palm, Radial deviation of finger, Proximal placement of thumb, Sporadic, Phenotypic va

How does someone get tested for Witteveen-Kolk syndrome (WITKOS)?

The initial testing for Witteveen-Kolk syndrome can begin with facial analysis screening, through the FDNA Telehealth telegenetics platform, which can identify the key markers of the syndrome and outline the need for further testing. A consultation with a genetic counselor and then a geneticist will follow. 

Based on this clinical consultation with a geneticist, the different options for genetic testing will be shared and consent will be sought for further testing.   

Medical information on Witteveen-Kolk syndrome (WITKOS)

Cushman et al. (2005) described three patients with interstitial deletion in the 15q22.3q24 region. Clinical characteristics included hypotonia, developmental delay, central nervous abnormalities, micrognathia, ear abnormality, epicanthal folds, and genital anomaly (hypogonadism, hypospadias).
Witteveen et al. (2016) identified heterozygous loss-of-function mutations in the gene SIN3A in individuals who, in addition to mild intellectual disability and autism spectrum disorder, shared facial dysmorphism, microcephaly and short stature. In addition, he studied four individuals with microdeletions in the chromosomal region 15q24 overlapping the SIN3A gene. The clinical features of the individuals with microdeletions and the individuals with SIN3A mutations were similar and included thin hair, broad and high forehead, full eyelids, depressed nasal bridge in younger individuals, mildly downslanted palpebral fissures, pointed or prominent chin and small mouth. Later, facial phenotypes evolved into long faces. Several individuals had hearing loss and autistic spectrum disorder. Brain MRI scans in some individuals showed underdeveloped frontal lobes, ventriculomegaly, decreased white matter, thin corpus callosum and enlarged cerebellar tonsils.
Narumi-Kishimoto et al. (2018) reported a seven-year old female Japanese patient from a non-consanguineous family with Witteveen-Kolk syndrome due to a novel heterozygous frameshift SIN3A gene pathogenic variant. The patient presented with developmental and speech delay, mild intellectual disability, autism spectrum disorder, and poor motor coordination. Dysmorphic features included long face, depressed nasal bridge, downslanting palpebral fissures, thick ear helices, small hands, and fifth finger clinodactyly.

* This information is courtesy of the L M D.
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