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Au-Kline syndrome
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Condition

Au-Kline syndrome

Au-Kline syndrome is a multi-system disorder characterized by hypotonia, intellectual disability, developmental delays, and distinctive facial features.

Overview

Au-Kline syndrome is a condition that affects many body systems. Individuals typically present with weak muscle tone (hypotonia), intellectual disability, and delayed development. Speech and motor skill acquisition are often significantly delayed.

Symptoms

The clinical features of Au-Kline syndrome are varied and may include:

  • Developmental delays: Including delayed speech and walking.
  • Facial features: Long palpebral fissures, drooping eyelids (ptosis), shallow eye sockets, a broad nasal bridge, and a mouth held in an open position.
  • Oral abnormalities: A deep groove in the middle of the tongue, high-arched palate, or missing teeth (oligodontia).
  • Structural malformations: Heart, blood vessel, kidney, or bone abnormalities, such as aortic dilatation or spinal curvature (scoliosis).
  • Autonomic nervous system issues: Digestive problems, difficulty feeling pain, abnormal sweating, and inability to adjust to high heat.

Causes

Au-Kline syndrome is caused by mutations in the HNRNPK gene. This gene produces the hnRNP K protein, which acts as a docking station for DNA, RNA, and other proteins, helping to control gene activity and protein production. A shortage of this protein disrupts the normal development and function of several body systems, particularly the brain, leading to the symptoms associated with the syndrome.

Inheritance

This condition is inherited in an autosomal dominant pattern, meaning one copy of the altered gene in each cell is sufficient to cause the disorder. Most cases result from new (de novo) mutations that occur during the formation of reproductive cells or in early embryonic development, meaning there is typically no family history of the disorder.

Frequently Asked Questions

Baseline echocardiography and renal ultrasound are recommended at diagnosis. If initial studies are normal, repeat cardiac imaging (echocardiogram or MRI if aortic dilation was noted) every 1–2 years, and renal ultrasound every 2–3 years, or sooner if hypertension, hematuria, or urinary symptoms develop. Any new cardiovascular or renal findings warrant immediate specialist referral.
Intensive, multidisciplinary early intervention is key. Speech‑language therapy that incorporates augmentative and alternative communication (AAC) devices can foster language even when oral motor control is limited. Physical and occupational therapy focusing on gross‑motor strength, balance, and fine‑motor tasks (e.g., grasp, hand‑eye coordination) should start as soon as delays are noted, ideally multiple times per week. Consistency at home, such as daily motor‑play routines and picture‑exchange communication practice, reinforces clinical gains.
De novo mutations mean the parents do not carry the altered gene in their somatic cells, so the recurrence risk for another child is low (generally <1 %). However, germline mosaicism—where a parent’s reproductive cells carry the mutation—can raise the risk slightly. Genetic counseling with possible parental testing (including sensitive methods for low‑level mosaicism) can provide a more individualized risk estimate.
Children often have a deep midline tongue groove, high‑arched palate, and sometimes missing teeth, which increase the risk of malocclusion and plaque retention. A pediatric dentist should evaluate the child by age 2–3 years, and regular dental check‑ups (every 6 months) are advised. Use of a soft‑bristled toothbrush, fluoride toothpaste, and, when needed, orthodontic consultation to address palate shape or bite issues can prevent decay and improve speech articulation.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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