Atypical neuronal ceroid lipofuscinosis type 2 disease (CLN2): a case report

Case presentation: Thirty-one-year-old female patient, born from a non-consanguineous couple. Presenting with a referred normal psychomotor development as an infant and no history of gestational or perinatal complications. As of eight years old, she developed cognitive impairment associated with gait disturbances. On her first neurological evaluation, with thirteen years old, dysarthric speech, ataxia, dystonia and chorea were prominent. Epilepsy was evident by nineteen years old, with myoclonic jerks as the primary presentation, time at which the patient was aphasic. As the years progressed, there was significant worsening of the symptoms with loss of hand abilities and the deambulatory capability by twenty-three years old. On the latest follow-up, the patient had no eye contact and displayed spastic palsy, truncal hypotonia, ataxia and extrapyramidal symptoms. MRI with spectroscopy studies showed diffuse cerebral atrophy, white matter signal alterations, reduced N-acetyl aspartate peak and no lactate or choline peak variation. Electroretinogram was not feasible due to technical limitations. Molecular studies using next-generation sequencing (NGS) revealed two heterozygous mutations on the Tripeptidyl Peptidase 1 (TPP1) gene – c.899delG and c.1340G>A, being the latter previously described in association with CLN2.

Discussion: CLN2 is an autosomal recessive neurodegenerative disorder, caused by reduced or absent activity on the TPP1 enzyme. Typical phenotypes have symptom onset between 2 and 4 years old (late infantile) with a rapid progression, marked epilepsy, visual, motor and speech impairments, resulting on early death. The presented case exhibits an atypical form, with later onset, slower progression, seizures starting later in life, important ataxia and a more evident movement disorder, which corroborates with literature descriptions of atypical forms. Recent studies analyze the effectiveness of cerliponase alfa on both typical and atypical cases of CLN2 and are indicating potential benefits as to the stabilization of the disease progression.

Final comments: CLN2 implicates on high morbidity and mortality rates for patients’ lives. Hence, early diagnosis is important to determine prognosis and to evaluate the possibility of treatment with cerliponase alfa. NGS facilitates the identification of atypical cases, allowing for a better understanding of the conditions’ features and the patients’ needs.

No conflict of interest has been declared by the author(s).

Publication History

Article published online:
18 September 2023